2008 : WHAT HAVE YOU CHANGED YOUR MIND ABOUT? WHY?

I have changed my mind about the nature of perception. I thought that a goal of perception is to estimate properties of an objective physical world, and that perception is useful precisely to the extent that its estimates are veridical. After all, incorrect perceptions beget incorrect actions, and incorrect actions beget fewer offspring than correct actions. Hence, on evolutionary grounds, veridical perceptions should proliferate.

Although the image at the eye, for instance, contains insufficient information by itself to recover the true state of the world, natural selection has built into the visual system the correct prior assumptions about the world, and about how it projects onto our retinas, so that our visual estimates are, in general, veridical. And we can verify that this is the case, by deducing those prior assumptions from psychological experiments, and comparing them with the world. Vision scientists are now succeeding in this enterprise. But we need not wait for their final report to conclude with confidence that perception is veridical. All we need is the obvious rhetorical question: Of what possible use is non-veridical perception?

I now think that perception is useful because it is not veridical. The argument that evolution favors veridical perceptions is wrong, both theoretically and empirically. It is wrong in theory, because natural selection hinges on reproductive fitness, not on truth, and the two are not the same: Reproductive fitness in a particular niche might, for instance, be enhanced by reducing expenditures of time and energy in perception; true perceptions, in consequence, might be less fit than niche-specific shortcuts. It is wrong empirically: mimicry, camouflage, mating errors and supernormal stimuli are ubiquitous in nature, and all are predicated on non-veridical perceptions. The cockroach, we suspect, sees little of the truth, but is quite fit, though easily fooled, with its niche-specific perceptual hacks. Moreover, computational simulations based on evolutionary game theory, in which virtual animals that perceive the truth compete with others that sacrifice truth for speed and energy-efficiency, find that true perception generally goes extinct.

It used to be hard to imagine how perceptions could possibly be useful if they were not true. Now, thanks to technology, we have a metaphor that makes it clear — the windows interface of the personal computer. This interface sports colorful geometric icons on a two-dimensional screen. The colors, shapes and positions of the icons on the screen are not true depictions of what they represent inside the computer. And that is why the interface is useful. It hides the complexity of the diodes, resistors, voltages and magnetic fields inside the computer. It allows us to effectively interact with the truth because it hides the truth.

It has not been easy for me to change my mind about the nature of perception. The culprit, I think, is natural selection. I have been shaped by it to take my perceptions seriously. After all, those of our predecessors who did not, for instance, take their tiger or viper or cliff perceptions seriously had less chance of becoming our ancestors. It is apparently a small step, though not a logical one, from taking perception seriously to taking it literally. 

Unfortunately our ancestors faced no selective pressures that would prevent them from conflating the serious with the literal: One who takes the cliff both seriously and literally avoids harms just as much as one who takes the cliff seriously but not literally. Hence our collective history of believing in flat earth, geocentric cosmology, and veridical perception. I should very much like to join Samuel Johnson in rejecting the claim that perception is not veridical, by kicking a stone and exclaiming "I refute it thus." But even as my foot ached from the ill-advised kick, I would still harbor the skeptical thought, "Yes, you should have taken that rock more seriously, but should you take it literally?"

Sometimes the later Roman empire seems very long ago and far away, but at other times, when we explore Edward Gibbon's famous claim to have described the triumph of "barbarism and religion", it can seem as fresh as next week.  And we always know that we're supposed root for the Romans.  When I began my career as historian thirty years ago, I was all in favor of those who were fighting to preserve the old order.  "I'd rather be Belisarius than Stilicho," I said to my classes often enough that they heard it as a mantra of my attitude — preferring the empire-restoring Roman general of the sixth-century to the barbarian general who served Rome and sought compromise and adjustment with neighbors in the fourth.  

But a career as a historian means growth, development, and change.  I did what the historian — as much a scientist as any biochemist, as the German use of the word Wissenschaft for what both practice — should do:  I studied the primary evidence, I listened to and participated in the debates of the scholars.  I had moments when a new book blew me away, and others when I read the incisive critique of the book that had blown me away and thought through the issues again.  I've been back and forth over a range of about four centuries of late Roman history many times now, looking at events, people, ideas, and evidence in different lights and moods.

What I have found is that the closer historical examination comes to the lived moment of the past, the harder it is to take sides with anybody.  And it is a real fact that the ancient past (I'm talking now about the period from 300-700 CE) draws closer and closer to us all the time.  There is a surprisingly large body of material that survives and really only a handful of hardy scholars sorting through it.  Much remains to be done:  The sophist Libanius of Antioch in the late fourth century, partisan for the renegade 'pagan' emperor Julian, left behind a ton of personal letters and essays that few have read, only a handful have been translated, and so only a few scholars have really worked through his career and thought — but I'd love to read, and even more dearly love to write, a good book about him someday.  In addition to the books, there is a growing body of archaeological evidence as diggers fan out across the Mediterranean, Near East, and Europe, and we are beginning to see new kinds of quantitative evidence as well — climate change measured from tree-ring dating, even genetic analysis that suggests that my O'Donnell ancestors came from one of the most seriously inbred populations (Ireland) on the planet — and right now the argument is going on about the genetic evidence for the size of the Anglo-Saxon migrations to Britain.  We know more than we ever did, and we are learning more all the time, and with each decade, we get closer and closer to even the remote past.  

When you do that, you find that the past is more a tissue of  choices and chances than we had imagined, that fifty or a hundred years of bad times can happen — and can end and be replaced by the united work of people with heads and hearts that makes society peaceful and prosperous again; or the opportunity can be kicked away.  

And we should remember that when we root for the Romans, there are contradictory impulses at work.  Rome brought the ancient world a secure environment (Pompey cleaning up the pirates in the Mediterranean was a real service), a standard currency, and a huge free trade zone.  Its taxes were heavy, but the wealth it taxed so immense that it could support a huge bureaucracy for a long time without damaging local prosperity.  Fine:  but it was an empire by conquest, ruled as a military dictatorship, fundamentally dependent on a slave economy, and with no clue whatever about the realities of economic development and management.  A prosperous emperor was one who managed by conquest or taxation to bring a flood of wealth into the capital city and squander it as ostentatiously as possible.  Rome "fell", if that's the right word for it, partly because it ran out of ideas for new peoples to plunder, and fell into a funk of outrage at the thought that some of the neighboring peoples preferred to move inside the empire's borders, settle down, buy fixer-upper houses, send their kids to the local schools, and generally enjoy the benefits of civilization.  (The real barbarians stayed outside.)  Much of the worst damage to Rome was done by Roman emperors and armies thrashing about, thinking they were preserving what they were in fact destroying.

So now I have a new mantra for my students:  "two hundred years is a long time."  When we talk about Shakespeare's time or the Crusades or the Roman Empire or the ancient Israelites, it's all too easy to talk about centuries as objects, a habit we bring even closer to our own time, but real human beings live in the short window of a generation, and with ancient lifespans shorter than our own, that window was brief.  We need to understand and respect just how much possibility was there and how much accomplishment was achieved if we are to understand as well the opportunities that were squandered.  Learning to do that, learning to sift the finest grains of evidence with care, learning to learn from and debate with others — that's how history gets done.  

The excitement begins when you discover that the past is constantly changing.

When facts change your mind, that's not always science. It may be history. I changed my mind about an important historical question: did the nuclear bombings of Hiroshima and Nagasaki bring World War Two to an end? Until this year I used to say, perhaps. Now, because of new facts, I say no. This question is important, because the myth of the nuclear bombs bringing the war to an end is widely believed. To demolish this myth may be a useful first step toward ridding the world of nuclear weapons.

Until the last few years, the best summary of evidence concerning this question was a book, "Japan's Decision to Surrender", by Robert Butow, published in 1954. Butow interviewed the surviving Japanese leaders who had been directly involved in the decision. He asked them whether Japan would have surrendered if the nuclear bombs had not been dropped. His conclusion, "The Japanese leaders themselves do not know the answer to that question, and if they cannot answer it, neither can I". Until recently, I believed what the Japanese leaders said to Butow, and I concluded that the answer to the question was unknowable.

Facts causing me to change my mind were brought to my attention by Ward Wilson. Wilson summarized the facts in an article, "The Winning Weapon? Rethinking Nuclear Weapons in the Light of Hiroshima", in the Spring 2007 issue of the magazine, "International Security". He gives references to primary source documents and to analyses published by other historians, in particular by Robert Pape and Tsuyoshi Hasegawa. The facts are as follows:

1. Members of the Supreme Council, which customarily met with the Emperor to take important decisions, learned of the nuclear bombing of Hiroshima on the morning of August 6, 1945. Although Foreign Minister Togo asked for a meeting, no meeting was held for three days.

2. A surviving diary records a conversation of Navy Minister Yonai, who was a member of the Supreme Council, with his deputy on August 8. The Hiroshima bombing is mentioned only incidentally. More attention is given to the fact that the rice ration in Tokyo is to be reduced by ten percent.

3. On the morning of August 9, Soviet troops invaded Manchuria. Six hours after hearing this news, the Supreme Council was in session. News of the Nagasaki bombing, which happened the same morning, only reached the Council after the session started.

4. The August 9 session of the Supreme Council resulted in the decision to surrender.

5. The Emperor, in his rescript to the military forces ordering their surrender, does not mention the nuclear bombs but emphasizes the historical analogy between the situation in 1945 and the situation at the end of the Sino-Japanese war in 1895. In 1895 Japan had defeated China, but accepted a humiliating peace when European powers led by Russia moved into Manchuria and the Russians occupied Port Arthur. By making peace, the emperor Meiji had kept the Russians out of Japan. Emperor Hirohito had this analogy in his mind when he ordered the surrender.

6. The Japanese leaders had two good reasons for lying when they spoke to Robert Butow. The first reason was explained afterwards by Lord Privy Seal Kido, another member of the Supreme Council: "If military leaders could convince themselves that they were defeated by the power of science but not by lack of spiritual power or strategic errors, they could save face to some extent". The second reason was that they were telling the Americans what the Americans wanted to hear, and the Americans did not want to hear that the Soviet invasion of Manchuria brought the war to an end.

In addition to the myth of two nuclear bombs bringing the war to an end, there are other myths that need to be demolished. There is the myth that, if Hitler had acquired nuclear weapons before we did, he could have used them to conquer the world. There is the myth that the invention of the hydrogen bomb changed the nature of nuclear warfare. There is the myth that international agreements to abolish weapons without perfect verification are worthless. All these myths are false. After they are demolished, dramatic moves toward a world without nuclear weapons may become possible.

I used to think that if something is clear and simple, it must also be provable or at least well defined, and if something is well defined, it might be relatively simple. It isn't so.

If you hear about sightings of a weird glow approaching us in the night sky, it might be explained as a meteorite or as little green men arriving in a spaceship from another galaxy. In most specific cases, both hypotheses can be neither proved nor disproved, rigorously. Nothing is well defined here. Yet, it is clear that the meteorite hypothesis is scientifically much more likely.

When you hear about a new perpetual motion machine or about yet another claim of cold fusion, you raise an eyebrow, you are willing to bet against it and, in your guts, you know it is wrong, but it is not always easy to disprove it rigorously.

The reliability of forecasts regarding weather, stock markets and astrology is descending in that order. All of them are based on guesses, with or without historical data. Most of them are rarely revisited by the media, after the fact, thus avoiding being exposed as unreliable. In most cases, predicting that the immediate future will be the same as the immediate past, has a higher probability of being correct, than the predictions of the gurus. Yet, we, as scientists, have considerable faith in weather predictions; much less faith in predicting peaks and dips of the stock market and no faith at all is astrology. We can explain why, and we are certainly right, but we cannot prove why. Proving it by historical success data, is as convincing (for the future) as the predictions themselves.

Richard Feynman in his famous Lectures on Physics provided the ultimate physics definition of Energy: It is that quantity which is conserved. Any Lawyer, Mathematician or Accountant would have laughed at this statement. Energy is perhaps the most useful, clear and common concept in all of science, and Feynman is telling us, correctly and shamelessly, that it has no proper rigorous and logical definition.

How much is five thousand plus two? Not so simple. Sometimes it is five thousands and two (as in your bank statement) and sometimes it is actually five thousand (as in the case of the Cairo tour guide who said "this pyramid is 5002 years old; when I started working here two years ago, I was told it was 5000 years old").

The public thinks, incorrectly, that science is a very accurate discipline where everything is well defined. Not so. But the beauty of it is that all of the above statements are scientific, obvious and useful, without being precisely defined. That is as much part of the scientific method as verifying a theory by an experiment (which is always accurate only to a point).

To speak and to understand the language of science is, among other things, to understand this "clear vagueness". It exists, of course, in other areas of life. Every normal language possesses numerous such examples, and so do all fields of social science.

Judaism is a religion and I am an atheist. Nevertheless, it is clear that I am Jewish. It would take a volume to explain why, and the explanation will remain rather obscure and ill defined. But the fact is simple, clear, well understood and undeniable.

Somehow, it is acceptable to face such situations in nonscientific matters, but most people think, incorrectly, that the quantitative natural sciences must be different. They are different, in many ways, but not in this way.

Common sense has as much place as logic, in scientific research. Intuition often leads to more insight than algorithmic thinking. Familiarity with previous failed attempts to solve a problem may be detrimental, rather than helpful. This may explain why almost all important physics breakthroughs are made by people under forty. This also explains why, in science, asking the right question is at least as important as being able to solve a well posed problem.

You might say that the above kind of thinking is prejudiced and inaccurate, and that it might hinder new discoveries and new scientific ideas. Not so. Good scientists know very well how to treat and use all of these "fuzzy" statements. They also know how to reconsider them, when there is a good reason to do so, based on new solid facts or on a new original line of thinking. This is one of the beautiful features of science.

I used to pride myself on the fact that I could explain almost anything to anyone, on a simple enough level, using analogies. No matter how abstract an idea in physics may be, there always seems to be some way in which we can get at least some part of the idea across. If colleagues shrugged and said, oh, well, that idea is too complicated or too abstract to be explained in simple terms, I thought they were either lazy or not very skilled in thinking creatively around a problem. I could not imagine a form of knowledge that could not be communicated in some limited but valid approximation or other.

However, I've changed my mind, in what was for me a rather unexpected way. I still think I was right in thinking that any type of insight can be summarized to some degree, in what is clearly a correct first approximation when judged by someone who shares in the insight. For a long time my mistake was that I had not realized how totally wrong this first approximation can come across for someone who does not share the original insight.

Quantum mechanics offers a striking example. When someone hears that there is a limit on how accurately you can simultaneously measure various properties of an object, it is tempting to think that the limitations lie in the measuring procedure, and that the object itself somehow can be held to have exact values for each of those properties, even if they cannot be measured. Surprisingly, that interpretation is wrong: John Bell showed that such a 'hidden variables' picture is actually in clear disagreement with quantum mechanics. An initial attempt at explaining the measurement problem in quantum mechanics can be more misleading than not saying anything at all.

So for each insight there is at least some explanation possible, but the same explanation may then be given for radically different insights. There is nothing that cannot be explained, but there are wrong insights that can lead to explanations that are identical to the explanation for a correct but rather subtle insight.

Sometimes you are glad to discover you were wrong. My best example of that kind of pleasant surprise is India. I'm delighted to see its recent rise, on (tentative) course toward economic, intellectual and social success. If these trends continue, it will matter a lot to Earth civilization, as a whole. The factors that fostered this trend appear to have been atypical — at least according to common preconceptions like "west and east" or "right vs left." I learned a lesson, about questioning my assumptions. 

Alas, there have been darker surprises. The biggest example has been America's slide into what could be diagnosed as bona fide Future Shock. 

Alvin Toffler appears to have sussed it. Back in 1999, while we were fretting over a silly "Y2K Bug" in ancient COBOL code, something else happened, at a deeper level. Our weird governance issues are only surface symptoms of what may have been a culture-wide crisis of confidence, upon the arrival of that "2" in the millennium column. Yes, people seemed to take the shift complacently, going about their business, But, underneath all the blithe shrugs, millions have turned their backs upon the future, even as a topic of discussion or interest.

Other than the tenacious grip of Culture War, what evidence can I offer? Well, in my own fields, let me point to a decline in the futurist-punditry industry. (A recent turnaround offers hope.) And a plummet in the popularity of science fiction literature (as opposed to feudal-retro fantasy.) John B. has already shown us how little draw science books offer, in the public imagination — an observation that not only matches my own, but also reflects the anti-modernist fervor displayed by all dogmatic movements. 

One casualty: the assertive, pragmatic approach to negotiation and human-wrought progress that used to be mother's milk to this civilization. 

Yes, there were initial signs of all this, even in the 1990s. But the extent of future-anomie and distaste for science took me completely by surprise. It makes me wonder why Toffler gets mentioned so seldom. 

Let me close with a final surprise, that's more of a disappointment. 

I certainly expected that, by now, online tools for conversation, work, collaboration and discourse would have become far more useful, sophisticated and effective than they currently are. I know I'm pretty well alone here, but all the glossy avatars and video and social network sites conceal a trivialization of interaction, dragging it down to the level of single-sentence grunts, flirtation and ROTFL [rolling on the floor laughing], at a time when we need discussion and argument to be more effective than ever. 

Indeed, most adults won't have anything to do with all the wondrous gloss that fills the synchronous online world, preferring by far the older, asynchronous modes, like web sites, email, downloads etc. 

This isn't grouchy old-fart testiness toward the new. In fact, there are dozens of discourse-elevating tools just waiting out there to be born. Everybody is still banging rocks together, while bragging about the colors. Meanwhile, half of the tricks that human beings normally use, in real world conversation, have never even been tried online.

Studying mathematical logic in the 1970s I believed it was possible to put together a convincing argument that no computer program can fully emulate a human mind. Although nobody had quite gotten the argument right, I hoped to straighten it out. 

My belief in this will-o-the-wisp was motivated by a gut feeling that people have numinous inner qualities that will not be found in machines.  For one thing, our self-awareness lets us reflect on ourselves and get into endless mental regresses: "I know that I know that I know..."  For another, we have moments of mystical illumination when we seem to be in contact, if not with God, then with some higher cosmic mind.  I felt that surely no machine could be self-aware or experience the divine light. 

At that point, I'd never actually touched a computer — they were still inaccessible, stygian tools of the establishment.  Three decades rolled by, and I'd morphed into a Silicon Valley computer scientist, in constant contact with nimble chips.  Setting aside my old prejudices, I changed my mind — and came to believe that we can in fact create human-like computer programs.

Although writing out such a program is in some sense beyond the abilities of any one person, we can set up simulated worlds in which such computer programs evolve.  I feel confident that some relatively simple set-up will, in time, produce a human-like program capable of emulating all known intelligent human behaviors: writing books, painting pictures, designing machines, creating scientific theories, discussing philosophy, and even falling in love.  More than that, we will be able to generate an unlimited number of such programs, each with its own particular style and personality. 

What of the old-style attacks from the quarters of mathematical logic?  Roughly speaking, these arguments always hinged upon a spurious belief that we can somehow discern between, on the one hand, human-like systems which are fully reliable and, on the other hand, human-like systems fated to begin spouting gibberish.  But the correct deduction from mathematical logic is that there is absolutely no way to separate the sheep from the goats.  Note that this is already our situation vis-a-vis real humans: you have no way to tell if and when a friend or a loved one will forever stop making sense. 

With the rise of new practical strategies for creating human-like programs and the collapse of the old a priori logical arguments against this endeavor, I have to reconsider my former reasons for believing humans to be different from machines.   Might robots become self-aware?  And — not to put too fine a point on it — might they see God?  I believe both answers are yes. 

Consciousness probably isn't that big a deal.  A simple pair of facing mirrors exhibit a kind of endlessly regressing self-awareness, and this type of pattern can readily be turned into computer code. 

And what about basking in the divine light?  Certainly if we take a reductionistic view that mystical illumination is just a bath of intoxicating brain chemicals, then there seems to be no reason that machines couldn't occasionally be nudged into exceptional states as well.  But I prefer to suppose that mystical experiences involve an objective union with a higher level of mind, possibly mediated by offbeat physics such as quantum entanglement, dark matter, or higher dimensions. 

Might a robot enjoy these true mystical experiences?  Based on my studies of the essential complexity of simple systems, I feel that any physical object at all must be equally capable of enlightenment.  As the Zen apothegm has it, "The universal rain moistens all creatures." 

So, yes, I now think that robots can see God.

For me, belief is not an all or nothing thing — believe or disbelieve, accept or reject.  Instead, I have degrees of belief, a subjective probability distribution over different possible ways the world could be.  This means that I am constantly changing my mind about all sorts of things, as I reflect or gain more evidence.  While I don't always thinkexplicitly in terms of probabilities, I often do so when I give careful consideration to some matter.  And when I reflect on my own cognitive processes, I must acknowledge the graduated nature of my beliefs. 

The commonest way in which I change my mind is by concentrating my credence function on a narrower set of possibilities than before.  This occurs every time I learn a new piece of information.  Since I started my life knowing virtually nothing, I have changed my mind about virtually everything.  For example, not knowing a friend's birthday, I assign a 1/365 chance (approximately) of it being the 11th of August.  After she tells me that the 11th of August is her birthday, I assign that date a probability of close to 100%.  (Never exactly 100%, for there is always a non-zero probability of miscommunication, deception, or other error.) 

It can also happen that I change my mind by smearing out my credence function over a wider set of possibilities.  I might forget the exact date of my friend's birthday but remember that it is sometime in the summer.  The forgetting changes my credence function, from being almost entirely concentrated on 11th of August to being spread out more or less evenly over all the summer months.  After this change of mind, I might assign a 1% probability to my friend's birthday being on the 11th of August.

My credence function can become more smeared out not only by forgetting but also by learning — learning that what I previously took to be strong evidence for some hypothesis is in fact weak or misleading evidence.  (This type of belief change can often be mathematically modeled as a narrowing rather than a broadening of credence function, but the technicalities of this are not relevant here.)

For example, over the years I have become moderately more uncertain about the benefits of medicine, nutritional supplements, and much conventional health wisdom.  This belief change has come about as a result of several factors.  One of the factors is that I have read some papers that cast doubt on the reliability of the standard methodological protocols used in medical studies and their reporting.  Another factor is my own experience of following up on MEDLINE some of the exciting medical findings reported in the media — almost always, the search of the source literature reveals a much more complicated picture with many studies showing a positive effect, many showing a negative effect, and many showing no effect.  A third factor is the arguments of a health economist friend of mine, who holds a dim view of the marginal benefits of medical care. 

Typically, my beliefs about big issues change in small steps.  Ideally, these steps should approximate a random walk, like the stock market.  It should be impossible for me to predict how my beliefs on some topic will change in the future.  If I believed that a year hence I will assign a higher probability to some hypothesis than I do today — why, in that case I could raise the probability right away.  Given knowledge of what I will believe in the future, I would defer to the beliefs of my future self, provided that I think my future self will be better informed than I am now and at least as rational. 

I have no crystal ball to show me what my future self will believe.  But I do have access to many other selves, who are better informed than I am on many topics.  I can defer to experts.  Provided they are unbiased and are giving me their honest opinion, I should perhaps always defer to people who have more information than I do — or to some weighted average of expert opinion if there is no consensus.  Of course, the proviso is a very big one: often I have reason to disbelieve that other people are unbiased or that they are giving me their honest opinion.  However, it is also possible that I am biased and self-deceiving.  An important unresolved question is how much epistemic weight a wannabe Bayesian thinker should give to the opinions of others.  I'm looking forward to changing my mind on that issue, hopefully by my credence function becoming concentrated on the correct answer.

The first topic you treat in freshman physics is showing how a ball shot straight up out of the mouth of a cannon will reach a maximum height and then fall back to Earth, unless its initial velocity, known now as escape velocity, is great enough that it breaks out of the Earth' gravitational field. If that is the case, its final velocity is however always less than its initial one. Calculating escape velocity may not be very relevant for cannon balls, but certainly is for rocket ships. 

The situation with the explosion we call the Big Bang is obviously more complicated, but really not that different, or so I thought. The standard picture said that there was an initial explosion, space began to expand and galaxies moved away from one another. The density of matter in the Universe determined whether the Big Bang would eventually be followed by a Big Crunch or whether the celestial objects would continue to move away from one another with decreasing acceleration. In other words one could calculate the Universe's escape velocity.  Admittedly the discovery of Dark Matter, an unknown quantity seemingly five times as abundant as known matter, seriously altered the framework but not in a fundamental way since Dark Matter was after all still matter, even if its identity is unknown. 

This picture changed in 1998 with the announcement by two teams, working independently, that the rate of acceleration of the Universe's expansion was increasing, not decreasing. It was as if freshman physics' cannonball miraculously moved faster and faster as it left the Earth. There was no possibility of a Big Crunch, in which the Universe would collapse back on itself. The groups' analyses, based on observing distant stars of known luminosity, supernovae 1a, was solid. Sciencemagazine dubbed it 1998's Discovery of The Year.

The cause of this apparent gravitational repulsion is not known. Called Dark Energy to distinguish it from Dark Matter, it appears to be the dominant force in the Universe's expansion, roughly three times as abundant as its Dark matter counterpart. The prime candidate for its identity is the so-called Cosmological Constant, a term first introduced into the cosmic gravitation equations by Einstein to neutralize expansion, but done away with by him when Hubble reported that the Universe was in fact expanding.

Finding a theory that will successfully calculate the magnitude of this cosmological constant, assuming this is the cause of the accelerating expansion, is perhaps the outstanding problem in the conjoined areas of cosmology and elementary particle physics. Despite many attempts, success does not seem to be in sight. If the cosmological constant is not the answer, an alternate explanation of the Dark Energy would be equally exciting. 

Furthermore the apparent present equality, to within a factor of three, of matter density and the cosmological constant has raised a series of important questions. Since matter density decreases rapidly as the Universe expands (matter per volume decreases as volume increases) and the cosmological constant does not, we seem to be living in that privileged moment of the Universe's history when the two factors are roughly equal. Is this simply an accident? Will the distant future really be one in which, with Dark Energy increasingly important, celestial objects have moved so far apart so quickly as to fade from sight? 

The discovery of Dark Energy has radically changed our view of the Universe. Future, keenly awaited findings, such as the identities of Dark Matter and Dark Energy will do so again.

I have never questioned the conventional view that a good grounding in the physical sciences is needed for a deep understanding of the biological sciences. It did not occur to me that the opposite view might also be true. If someone were to have asked me if biological knowledge might significantly influence my understanding of our basic physical sciences, I would have denied it.

Now I am convinced that the future understanding of our most important physical principles will be profoundly shaped by what we learn in the living realm of biology. What have changed my mind are the relatively recent developments in the theoretical constructs and empirical findings in the sciences of the brain — the biological foundation of all thought. Progress here can cast new light on the fundamental subjective factors that constrain our scientific formulations in what we take to be an objective enterprise.

The last thirty to forty years of social science has brought an overbearing censorship to the way we are allowed to think and talk about the diversity of people on Earth. People of Siberian descent, New Guinean Highlanders, those from the Indian sub-continent, Caucasians, Australian aborigines, Polynesians, Africans — we are, officially, all the same: there are no races. 

Flawed as the old ideas about race are, modern genomic studies reveal a surprising, compelling and different picture of human genetic diversity.  We are on average about 99.5% similar to each other genetically. This is a new figure, down from the previous estimate of 99.9%. To put what may seem like miniscule differences in perspective, we are somewhere around 98.5% similar, maybe more, to chimpanzees, our nearest evolutionary relatives. 

The new figure for us, then, is significant. It derives from among other things, many small genetic differences that have emerged from studies that compare human populations. Some confer the ability among adults to digest milk, others to withstand equatorial sun, others yet confer differences in body shape or size, resistance to particular diseases, tolerance to hot or cold, how many offspring a female might eventually produce, and even the production of endorphins — those internal opiate-like compounds. We also differ by surprising amounts in the numbers of copies of some genes we have. 

Modern humans spread out of Africa only within the last 60-70,000 years, little more than the blink of an eye when stacked against the 6 million or so years that separate us from our Great Ape ancestors. The genetic differences amongst us reveal a species with a propensity to form small and relatively isolated groups on which natural selection has often acted strongly to promote genetic adaptations to particular environments. 

We differ genetically more than we thought, but we should have expected this: how else but through isolation can we explain a single species that speaks at least 7,000 mutually unintelligible languages around the World? 

What this all means is that, like it or not, there may be many genetic differences among human populations — including differences that may even correspond to old categories of 'race' — that are real differences in the sense of making one group better than another at responding to some particular environmental problem. This in no way says one group is in general 'superior' to another, or that one group should be preferred over another.  But it warns us that we must be prepared to discuss genetic differences among human populations.

If my math had been better, I would have become an astronomer rather than a psychologist. I was after the very greatest questions and finding life elsewhere in the universe seemed the greatest of them all. Understanding thinking, emotion, and mental health was second best — science for weaker minds like mine.Carl Sagan and I were close colleagues in the late 1960's when we both taught at Cornell. I devoured his thrilling book with I.I. Shklovskii (Intelligent Life in the Universe, 1966) in one twenty-four hour sitting, and I came away convinced that intelligent life was commonplace across our galaxy.

The book, as most readers know, estimates a handful of parameters necessary to intelligent life, such as the probability that an advanced technical civilization will in short order destroy itself and the number of "sol-like" stars in the galaxy. Their conclusion is that there are between 10,000 and two million advanced technical civilizations hereabouts. Some of my happiest memories are of discussing all this with Carl, our colleagues, and our students into the wee hours of many a chill Ithaca night.And this made the universe a less chilly place as well. What consolation! That homo sapiens might really partake of something larger, that there really might be numerous civilizations out there populated by more intelligent beings than we are, wiser because they had outlived the dangers of premature self-destruction. What's more we might contact them and learn from them.

A fledging program of listening for intelligent radio signals from out there was starting up. Homo sapiens was just taking its first balky steps off the planet; we exuberantly watched the moon landing together at the faculty club. We worked on the question of how we would respond if humans actually heard an intelligent signal. What would our first "words" be? We worked on what would be inscribed on the almost immortal Voyager plaque that would leave our solar system just about now — allowing the sentient beings who cadged it epochs hence to surmise who we were, where we were, when we were, and what we were (Should the man and woman be holding hands? No, they might think we were one conjoined organism.) SETI (the Search for Extraterrestrial Intelligence) and its forerunners are almost forty years old. They scan the heavens for intelligent radio signals, with three million participants using their home computers to analyze the input. The result has been zilch. There are plenty of excuses for zilch, however, and lots of reason to hope: only a small fraction of the sky has been scanned and larger more efficient arrays are coming on line. Maybe really advanced civilizations don't use communication techniques that produce waves we can pick up.

Maybe intelligent life is so unimaginably different from us that we are looking in all the wrong "places." Maybe really intelligent life forms hide their presence.So I changed my mind. I now take the null hypothesis very seriously: that Sagan and Shklovskii were wrong: that the number of advanced technical civilizations in our galaxy is exactly one, that the number of advanced technical civilizations in the universe is exactly one.What is the implication of the possibility, mounting a bit every day, that we are alone in the universe? It reverses the millennial progression from a geocentric to a heliocentric to a Milky Way centered universe, back to, of all things, a geocentric universe. We are the solitary point of light in a darkness without end. It means that we are precious, infinitely so. It means that nuclear or environmental cataclysm is an infinitely worse fate than we thought.

It means that we have a job to do, a mission that will last all our ages to come: to seed and then to shepherd intelligent life beyond this pale blue dot.

Like many scientists in the field of memory, I used to think that a memory is something stored in the brain and then accessed when used. Then, in 2000, a researcher in my lab, Karim Nader, did an experiment that convinced me, and many others, that our usual way of thinking was wrong. In a nutshell, what Karim showed was that each time a memory is used, it has to be restored as a new memory in order to be accessible later. The old memory is either not there or is inaccessible. In short, your memory about something is only as good as your last memory about it. This is why people who witness crimes testify about what they read in the paper rather than what they witnessed. Research on this topic, called reconsolidation, has become the basis of a possible treatment for post-traumatic stress disorder, drug addiction, and any other disorder that is based on learning.

That Karim's study changed my mind is clear from the fact that I told him, when he proposed to do the study, that it was a waste of time. I'm not swayed by arguments based on faith, can be moved by good logic, but am always swayed by a good experiment, even if it goes against my scientific beliefs. I might not give up on a scientific belief after one experiment, but when the evidence mounts over multiple studies, I change my mind.

I used to believe that there were experts and non-experts and that, on the whole, the judgment of experts is more accurate, more valid, and more correct than my own judgment. But over the years, thinking — and I should add, experience — has changed my mind. What experts have that I don't are knowledge and experience in some specialized area. What, as a class, they don't have any more than I do is the skills of judgment, rational thinking and wisdom. And I've come to believe that some highly ‘qualified' people have less of that than I do.

I now believe that the people I know who are wise are not necessarily knowledgeable; the people I know who are knowledgeable are not necessarily wise. Most of us confuse expertise with judgment. Even in politics, where the only qualities politicians have that the rest of us lack are knowledge of the procedures of parliament or congress, and of how government works, occasionally combined with specific knowledge of economics or foreign affairs, we tend to look to such people for wisdom and decision-making of a high order.

Many people enroll for MBA's to become more successful businessmen. An article in Fortune magazine a couple of years ago compared the academic qualifications of people in business and found the qualification that correlated most highly with success was a philosophy degree. When I ran a television production company and was approached for a job by budding directors or producers, I never employed anyone with a degree in media studies. But I did employ lots of intelligent people with good judgment who knew nothing about television to start with but could make good decisions. The results justified that approach.

Scientists — with a few eccentric exceptions — are, perhaps, the one group of experts who have never claimed for themselves wisdom outside the narrow confines of their specialties. Paradoxically, they are the one group who are blamed for the mistakes of others. Science and scientists are criticized for judgments about weapons, stem cells, global warming, nuclear power, when the decisions are made by people who are not scientists.

As a result of changing my mind about this, I now view the judgments of others, however distinguished or expert they are, as no more valid than my own. If someone who is a ‘specialist' in the field disagrees with me about a book idea, the solution to the Middle East problems, the non-existence of the paranormal or nuclear power, I am now entirely comfortable with the disagreement because I know I'm just as likely to be right as they are.

Our science, including mine, treats living systems as mechanisms at multiple levels of abstraction.  As we talk about how one bio-molecule docks with another our explanations are purely mechanistic and our science never invokes "and then the soul intercedes and gets them to link up". The underlying assumption of molecular biologists is that their level of mechanistic explanation is ultimately adequate for high level mechanistic descriptions such as physiology and neuroscience to build on as a foundation.

Those of us who are computer scientists by training, and I'm afraid many collaterally damaged scientists of other stripes, tend to use computation as the mechanistic level of explanation for how living systems behave and "think".  I originally gleefully embraced the computational metaphor

If we look back over recent centuries we will see the brain described as a hydrodynamic machine, clockwork, and as a steam engine.  When I was a child in the 1950's I read that the human brain was a telephone switching network.  Later it became a digital computer, and then a massively parallel digital computer.  A few years ago someone put up their hand after a talk I had given at the University of Utah and asked a question I had been waiting for for a couple of years: "Isn't the human brain just like the world wide web?".  The brain always seems to be one of the most advanced technologies that we humans currently have.

The metaphors we have used in the past for the brain have not stood the test of time.  I doubt that our current metaphor of the brain as a network of computers doing computations is going to stand for all eternity either.

Note that I do not doubt that there are mechanistic explanations for how we think, and I certainly proceed with my work of trying to build intelligent robots using computation as a primary tool for expressing mechanisms within those robots.

But I have relatively recently come to question computation as the ultimate metaphor to be used in both the understanding of living systems and as the only important design tool for engineering intelligent artifacts.

Some of my colleagues have managed to recast Pluto's orbital behavior as the body itself carrying out computations on forces that apply to it.  I think we are perhaps better off using Newtonian mechanics (with a little Einstein thrown in) to understand and predict the orbits of planets and others.  It is so much simpler.

Likewise we can think about spike trains as codes and worry about neural coding.  We can think about human memory as data storage and retrieval.  And we can think about walking over rough terrain as computing the optimal place to put down each of our feet.  But I suspect that somewhere down the line we are going to come up with better, less computational metaphors.  The entities we use for metaphors may be more complex but the useful ones will lead to simpler explanations.

Just as the notion of computation is only a short step beyond discrete mathematics, but opens up vast new territories of questions and technologies, these new metaphors might well be just a few steps beyond where we are now in understanding organizational dynamics, but they may have rich and far reaching implications in our abilities to understand the natural world and to engineer new creations.

When I first saw the possibility (some 30 years ago) of grounding a science of human self-deception in evolutionary logic (based on its value in furthering deception of others), I imagined joining evolutionary theory with animal behavior and with those parts of psychology worth preserving. The latter I regarded as a formidable hurdle since so much of psychology (depth and social) appeared to be pure crap, or more generously put, without any foundation in reality or logic.

Now after a couple of years of intensive study of the subject, I am surprised at the number of areas of biology that are important, if not key, to the subject yet are relatively undeveloped by biologists. I am also surprised that many of the important new findings in this regard have been made by psychologists and not biologists.

It was always obvious that when neurophysiology actually became a science (which it did when it learned to measure on-going mental activity) it would be relevant to deceit and self-deception and this is becoming more apparent every day. Also, endocrinology could scarcely be irrelevant and Richard Wrangham has recently argued for an intimate connection between testosterone and self-deception in men but the connections must be much deeper still. The proper way to conceptualize the endocrine system (as David Haig has pointed out to me) is as a series of signals with varying half-lives which give relevant information to organs downstream and many such signals may be relevant to deceit and self-deception and to selves-deception, as defined below.

One thing I never imagined was that the immune system would be a vital component of any science of self-deception, yet two lines of work within psychology make this clear. Richard Davidson and co-workers have shown that relatively positive, up, approach-seeking people are more likely to be left-brain activated (as measured by EEG) and show stronger immune responses to a novel challenge (flu vaccine) than are avoidance, negative emotion (depression, anxiety) right-brained people.  At the same time, James Pennebaker and colleagues have shown that the very act of repressing information from consciousness lowers immune function while sharing information with others (or even a diary) has the opposite effect. Why should the immune system be so important and why should it react in this way?

A key variable in my mind is that the immune system is an extremely expensive one—we produce a grapefruit-sized set of tissue every two weeks—and we can thus borrow against it, apparently in part for brain function. But this immediately raises the larger question of how much we can borrow against any given system—yes fat for energy, bone and teeth when necessary (as for a child in utero), muscle when not used and so on—but with what effects? Why immune function and repression?

While genetics is, in principle, important to all of biology, I thought it would be irrelevant to the study of self-deception until way into the distant future. Yet the 1980s produced the striking discovery that the maternal half of our genome could act against the paternal, and vice-versa, discoveries beautifully exploited in the 90’s and 00’s by David Haig to produce a range of expected (and demonstrated) internal conflicts which must inevitably interact with self-deception directed toward others. Put differently, internal genetic conflict leads to a quite novel possibility: selves-deception, equally powerful maternal and paternal halves selected to deceive each other (with unknown effects on deception of others).

And consider one of the great mysteries of mental biology. The human brain consumes about 20% of resting metabolic rate come rain or shine, whether depressed or happy, asleep or awake. Why? And why is the brain so quick to die when deprived of this energy? What is the cellular basis for all of this? How exactly does borrowing from other systems, such as immune, interact with this basic metabolic cost? Biologists have been very slow to see the larger picture and to see that fundamental discoveries within psychobiology require a deeper understanding of many fundamental biological processes, especially the logic of energy borrowed from various sources.

Finally, let me express a surprise about psychology. It has led the way in most of the areas mentioned, e.g. immune effects, neurophysiology, brain metabolism. Also, while classical depth psychology (Freud and sundries) can safely be thrown overboard almost in its entirety, social psychology has produced some very clever and hopeful methods, as well as a body of secure results on biased human mentation, from perception, to organization of data, to analysis, to further propagation. Daniel Gilbert gives a well-appreciated lecture in which he likens the human mind to a bad scientist, everything from biased exposure to data and biased analysis of information to outright forgery. Hidden here is a deeper point. Science progresses precisely because it has a series of anti-deceit-and-self-deception devices built into it, from full description of experiments permitting exact replication, to explicit statement of theory permitting precise counter-arguments, to the preference for exploring alternative working hypothesis, to a statistical apparatus able to weed out the effects of chance, and so on.

The year 2007 marked three memorable events in climate science:  Release of the Fourth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC AR4); a decade of drought in the American West and the arrival of severe drought in the American Southeast; and the disappearance of nearly half of the polar sea-ice floating over the Arctic Ocean. The IPCC report (a three-volume, three-thousand page synthesis of current scientific knowledge written for policymakers) and the American droughts merely hardened my conviction that anthropogenic climate warming is real and just getting going — a view shared, in the case of the IPCC, a few weeks ago by the Nobel Foundation. The sea-ice collapse, however, changed my mind that it will be decades before we see the real impacts of the warming. I now believe they will happen much sooner.

Let's put the 2007 sea-ice year into context. In the 1970's, when NASA first began mapping sea ice from microwave satellites, its annual minimum extent (in September, at summer's end) hovered close to 8 million square kilometers, about the area of the conterminous United States minus Ohio. In September 2007 it dropped abruptly to 4.3 million square kilometers, the area of the conterminous United State minus Ohio and all the other twenty-four states east of the Mississippi, as well as North Dakota, Minnesota, Missouri, Arkansas, Louisiana, and Iowa. Canada's Northwest Passage was freed of ice for the first time in human memory. From Bering Strait where the U.S. and Russia brush lips, open blue water stretched almost to the North Pole.

What makes the 2007 sea-ice collapse so unnerving is that it happened too soon.  The ensemble averages of our most sophisticated climate model predictions, put forth in the IPCC AR4 report and various other model intercomparison studies, don't predict a downwards lurch of that magnitude for another fifty years. Even the aggressive models -the National Center for Atmospheric Research (NCAR) CCSM3 and the Centre National de Recherches Meteorologiques (CNRM) CM3 simulations, for example — must whittle ice until 2035 or later before the 2007 conditions can be replicated.  Put simply, the models are too slow to match reality. Geophysicists, accustomed to non-linearities and hard to impress after a decade of 'unprecedented' events, are stunned by the totter:  Apparently, the climate system can move even faster than we thought.  This has decidedly recalibrated scientist's attitudes — including my own — to the possibility that even the direst IPCC scenario predictions for the end of this century — 10 to 24 inch higher global sea levels, for example — may be prudish.

What does all this say to us about the future? The first is that rapid climate change — a nonlinearity that occurs when a climate forcing reaches a threshold beyond which little additional forcing is needed to trigger a large impact — is a distinct threat not well captured in our current generation of computer models. This situation will doubtless improve — as the underlying physics of the 2007 ice event and others such as the American Southeast drought are dissected, understood, and codified — but in the meantime, policymakers must work from the IPCC blueprint which seems almost staid after the events of this summer and fall.  The second is that it now seems probable that the northern hemisphere will lose its ice lid far sooner than we ever thought possible.  Over the past three years experts have shifted from 2050, to 2035, to 2013 as plausible dates for an ice-free Arctic Ocean — estimates at first guided by models then revised by reality.

The broader significance of vanishing sea ice extends far beyond suffering polar bears, new shipping routes, or even development of vast Arctic energy reserves. It is absolutely unequivocal that the disappearance of summer sea ice — regardless of exactly which year it arrives — will profoundly alter the northern hemisphere climate, particularly through amplified winter warming of at least twice the global average rate. Its further impacts on the world's precipitation and pressure systems are under study but are likely significant. Effects both positive and negative, from reduced heating oil consumption to outbreaks of fire and disease, will propagate far southward into the United States, Canada, Russia and Scandinavia. Scientists have expected such things in eventuality — but in 2007 we learned they may already be upon us.

In an interview with the New York Times, shortly before he died, Francis Crick told a reporter, "the view of ourselves as [ensouled] 'persons' is just as erroneous as the view that the Sun goes around the Earth. This sort of language will disappear in a few hundred years. In the fullness of time, educated people will believe there is no soul independent of the body, and hence no life after death."

Like the vast majority of academic scientists and philosophers alive today, I accept Crick's philosophical assertion — that when your body dies, you cease to exist — without any reservations. I also used to agree with Crick's psychosocial prognosis — that modern education would inevitably give rise to a populace that rejected the idea of a supernatural soul. But on this point, I have changed my mind.

Underlying Crick's psychosocial claim is a common assumption: the minds of all intelligent people must operate according to the same universal principles of human nature. Of course, anyone who makes this assumption will naturally believe that their own mind-type is the universal one. In the case of Crick and most other molecular biologists, the assumed universal mind-type is highly receptive to the persuasive power of pure logic and rational analysis.

Once upon a time, my own worldview was similarly informed. I was convinced that scientific facts and rational argument alone could win the day with people who were sufficiently intelligent and educated. To my mind, the rejection of rational thought by such people was a sign of disingenuousness to serve political or ideological goals.

My mind began to change one evening in November 2003. I had given a lecture at small liberal arts college along with a member of The President's Council on Bioethics, whose views on human embryo research are diametrically opposed to my own. Surrounded by students at the wine and cheese reception that followed our lectures, the two of us began an informal debate about the true meaning and significance of changes in gene expression and DNA methylation during embryonic development. Six hours later, long after the last student had crept off to sleep, it was 4:00 am, and we were both still convinced that with just one more round of debate, we'd get the other to capitulate. It didn't happen.

Since this experience, I have purposely engaged other well-educated defenders of the irrational, as well as numerous students at my university, in spontaneous one-on-one debates about a host of contentious biological subjects including evolution, organic farming, homeopathy, cloned animals, "chemicals" in our food, and genetic engineering. Much to my chagrin, even after politics, ideology, economics, and other cultural issues have been put aside, there is often a refusal to accept scientific implications of rational argumentation.

While its mode of expression may change over cultures and time, irrationality and mysticism seem to be an integral part of normal human nature, even among highly educated people. No matter what scientific and technological advances are made in the future, I now doubt that supernatural beliefs will ever be eradicated from the human species.

When I was in graduate school, in the early 1990s, I learned two important things: that the human capacity for language was innate, and that the machinery that allowed human beings to learn language was "special", in the sense of being separate from the rest of the human mind.

Both ideas sounded great at the time. But (as far as I can tell know) only one of them turns out to be true.

I still think that I was right to believe in "innateness", the idea that the human mind, arrives, fresh from the factory, with a considerable amount of elaborate machinery. When a human embryo emerges from the womb, it has almost all the neurons it will ever have. All of the basic neural structures are already in place, and most or all of the basic neural pathways are established. There is, to be sure, lots of learning yet to come — an infant's brain is more rough draft than final product — but anybody who still imagines the infant human mind to be little more than an empty sponge isn't in touch with the realities of modern genetics and neuroscience. Almost half our genome is dedicated to the development of brain function, and those ten or fifteen thousand brain-related genes choreograph an enormous amount of biological sophistication.  Chomsky (whose classes I sat in on while in graduate school) was absolutely right to be insisting, for all these years, that language has its origins in the built-in structure of the mind.

But now I believe that I was wrong to accept the idea that language was separate from the rest of the human mind. It's always been clear that we can talk about what we think about, but when I was in graduate school it was popular to talk about language as being acquired by a separate "module" or "instinct" from the rest of cognition, by what Chomsky called a  "Language Acquisition Device" (or LAD). Its mission in life was to acquire language, and nothing else. 

In keeping with idea of language as product of specialized in-born mechanism, we noted how quickly how human toddlers acquired language, and how determined they were to do so; all normal human children acquire language, not just a select few raised in privileged environments, and they manage to do so rapidly, learning most of what they need to know in the first few years of life.  (The average adult, in contrast, often gives up around the time they have to face their fourth list of irregular verbs.)  Combine that with the fact that some children with normal intelligence couldn't learn language and that others with normal language lacked normal cognitive function, and I was convinced. Humans acquired language because they had a built-in module that was uniquely dedicated to that function.

Or so I thought then. By the late 1990s, I started looking beyond the walls of my own field (developmental psycholinguistics) and out towards a whole host of other fields, including genetics, neuroscience, and evolutionary biology.

The idea that most impressed me — and did the most to shake me of the belief that language was separate from the rest of the mind — goes back to Darwin. Not "survival of the fittest" (a phrase actually coined by Herbert Spencer) but his notion, now amply confirmed at the molecular level, that all biology is the product of what he called "descent with modification". Every species, and every biological system evolves through a combination of inheritance (descent) and change (modification). Nothing, no matter how original it may appear, emerges from scratch.

Language, I ultimately realized, must be no different: it emerged quickly, in the space of a few hundred thousand years, and with comparatively little genetic change. It suddenly dawned on me that the striking fact that our genomes overlap almost 99% with those of chimpanzees must be telling something: language couldn't possibly have started from scratch. There isn't enough room in the genome, or in our evolutionary history, for it to be plausible that language is completely separate from what came before.

Instead, I have now come to believe, language must be, largely, a recombination of spare parts, a kind of jury-rigged kluge built largely out of cognitive machinery that evolved for other purposes, long before there was such a thing as language. If there's something special about language, it is not the parts from which it is composed, but the way in which they are put together.

Neuorimaging studies seem to bear this out. Whereas we once imagined language to be produced and comprehended almost entirely by two purpose-built regions — Broca's area and Wernicke's area, we now see that many other parts of the brain are involved (e.g. the cerebellum and basal ganglia) and that the classic language areas (i.e. Broca's and Wernicke's) participate in other aspects of mental life (e.g., music and motor control) and have counterparts in other apes.

At the narrowest level, this means that psycholinguists and cognitive neuroscientists need to rethink their theories about what language is. But if there is a broader lesson, it is this: although we humans in many ways differ radically from any other species, our greatest gifts are built upon a genomic bedrock that we share with the many other apes that walk the earth.

I have a collection of web pages on the sustainability of material progress that treats many problems that have been proposed as possible stoppers. I get email about the pages, both unfavorable and favorable, mostly the latter.

I had believed that the email would concern specific problems or would raise new ones, e.g. "What about erosion of agricultural land?"

There's some of that, but overwhelmingly the email, both pro and con, concerns my attitude,  not my (alleged) facts. "How can you be so blithely cornucopian when everybody knows ..." or "I'm glad someone has the courage to take on all those doomsters."

It seems, to my surprise, that people's attitude that the future stems at least as much from personality as from opinions about facts. People look for facts to support their attitudes — which have earlier antecedents.

I have changed my mind about my body. I used to think of it as a kind of hardware on which my mental and behavioral software was running. Now, I primarily think of my body as software. 

My body is not like a typical material object, a stable thing.  It is more like a flame, a river or an eddie. Matter is flowing through it all the time. The constituents are being replaced over and over again.

A chair or a table is stable because the atoms stay where they are. The stability of a river stems from the constant flow of water through it.

98 percent of the atoms in the body are replaced every year. 98 percent! Water molecules stays in your body for two weeks (and for an even shorter time in a hot climate), the atoms in your bones stays there for a few months. Some atoms stay for years. But almost not one single atom stay with you in your body from cradle to grave.

What is constant in you is not material. An average person takes in 1.5 ton of matter every year as food, drinks and oxygen. All this matter has to learn to be you. Every year. New atoms will have to learn to remember your childhood.

These numbers has been known for half a century or more, mostly from studies of radioactive isotopes. Physicist Richard Feynman said in 1955: "Last week's potatoes! They now can remember what was going on in your mind a year ago."

But why is this simple insight not on the all-time Top 10 list of important discoveries? Perhaps because it tastes a little like spiritualism and idealism? Only the ghosts are for real? Wandering souls? 

But digital media now makes it possible to think of all this in a simple way. The music I danced to as a teenager has been moved from vinyl-LPs to magnetic audio tapes to CDs to Pods and whatnot. The physical representation can change and is not important — as long as it is there. The music can jump from medium to medium, but it is lost if it does not have a representation. This physics of information was sorted out by Rolf Landauer in the 1960'ies. Likewise, out memories can move from potato-atoms to burger-atoms to banana-atoms. But the moment they are on their own, they are lost.

We reincarnate ourselves all the time. We constantly give our personality new flesh. I keep my mental life alive by making it jump from atom to atom. A constant flow. Never the same atoms, always the same river. No flow, no river. No flow, no me.

This is what I call permanent reincarnation: Software replacing its hardware all the time. Atoms replacing atoms all the time. Life. This is very different from religious reincarnation with souls jumping from body to body (and souls sitting out there waiting for a body to take home in).

There has to be material continuity for permanent reincarnation to be possible. The software is what is preserved, but it cannot live on its own. It has to jump from molecule to molecule, always in carnation.

I have changed my mind about the stability of my body: It keeps changing all the time. Or I could not stay the same.

As a scientist, I am motivated to build an objective model of reality. Since we always have incomplete information, it is eminently rational to construct a Bayesian network of likelihoods — assigning a probability for each possibility, supported by a chain of priors. When new facts arise, or if new conditional relationships are discovered, these probabilities are adjusted accordingly — our minds should change. When judgment or action is required, it is based on knowledge of these probabilities. This method of logical inference and prediction is the sine qua non of rational thought, and the method all scientists aspire to employ. However, the ambivalence associated with an even probability distribution makes it terribly difficult for an ideal scientist to decide where to go for dinner.

Even though I strive to achieve an impartial assessment of probabilities for the purpose of making predictions, I cannot consider my assessments to be unbiased. In fact, I no longer think humans are naturally inclined to work this way. When I casually consider the beliefs I hold, I am not readily able to assign them numerical probabilities. If pressed, I can manufacture these numbers, but this seems more akin to rationalization than rational thought. Also, when I learn something new, I do not immediately erase the information I knew before, even if it is contradictory. Instead, the new model of reality is stacked atop the old. And it is in this sense that a mind doesn't change; vestigial knowledge may fade over a long period of time, but it isn't simply replaced. This model of learning matches a parable from Douglas Adams, relayed by Richard Dawkins:

A man didn't understand how televisions work, and was convinced that there must be lots of little men inside the box, manipulating images at high speed. An engineer explained to him about high frequency modulations of the electromagnetic spectrum, about transmitters and receivers, about amplifiers and cathode ray tubes, about scan lines moving across and down a phosphorescent screen. The man listened to the engineer with careful attention, nodding his head at every step of the argument. At the end he pronounced himself satisfied. He really did now understand how televisions work. "But I expect there are just a few little men in there, aren't there?"

As humans, we are inefficient inference engines — we are attached to our "little men," some dormant and some active. To a degree, these imperfect probability assessments and pet beliefs provide scientists with the emotional conviction necessary to motivate the hard work of science. Without the hope that an improbable line of research may succeed where others have failed, difficult challenges would go unmet. People should be encouraged to take long shots in science, since, with so many possibilities, the probability of something improbable happening is very high. At the same time, this emotional optimism must be tempered by a rational estimation of the chance of success — we must not be so optimistic as to delude ourselves. In science, we must test every step, trying to prove our ideas wrong, because nature is merciless. To have a chance of understanding nature, we must challenge our predispositions. And even if we can't fundamentally change our minds, we can acknowledge that others working in science may make progress along their own lines of research. By accommodating a diverse variety of approaches to any existing problem, the scientific community will progress expeditiously in unlocking nature's secrets.

An asteroid did it . . . .

Ok, so this may not seem like news to you. The father-son team of Luis and Walter Alvarez first put forth the asteroid hypothesis in 1980 to account for the extinction of dinosaurs and many other lifeforms at the end of the Mesozoic (about 65.5 million years ago). According to this now familiar scenario, an asteroid about 10 km in diameter slammed into the planet at about 100,000 km/hour. Upon impact, the bolide disintegrated, vaporizing a chunk of the earth's crust and propelling a gargantuan cloud of gas and dust high into the atmosphere. This airborne matter circulated around the globe, blocking out the sun and halting photosynthesis for a period of weeks or months. If turning the lights out wasn't bad enough, massive wild fires and copious amounts of acid rain apparently ensued. 

Put simply, it was hell on Earth. Species succumbed in great numbers and food webs collapsed the world over, ultimately wiping out about half of the planet's biodiversity. Key geologic evidence includes remnants of the murder weapon itself; iridium, an element that occurs in small amounts in the Earth's crust but is abundant in asteroids, was found by the Alvarez team to be anomalously abundant in a thin layer within Cretaceous-Tertiary (K-T) boundary sediments at various sites around the world. In 1990, announcement came of discovery of the actual impact crater in the Gulf of Mexico. It seemed as if arguably the most enduring mystery in prehistory had finally been solved. Unsurprisingly, this hypothesis was also a media darling, providing a tidy yet incredibly violent explanation to one of paleontology's most perplexing problems, with the added bonus of a possible repeat performance, this time with humans on the roster of victims.

To some paleontologists, however, the whole idea seemed just a bit too tidy.

Ever since the Alvarezes proposed the asteroid, or "impact winter," hypothesis, many (at times the bulk of) dinosaur paleontologists have argued for an alternative scenario to account for the K-T extinction. I have long counted myself amongst the ranks of doubters. It is not so much that I and my colleagues have questioned the occurrence of an asteroid impact; supporting evidence for this catastrophic event has been firmly established for some time. At issue has been the timing of the event. Whereas the impact hypothesis invokes a rapid extinction—on the order of weeks to years—others argue for a more gradual dying that spanned from one million to several million years. Evidence cited in support of the latter view includes an end-Cretaceous drop in global sea levels and a multi-million year bout of volcanism that makes Mount St. Helens look like brushfire. 

Thus, at present the debate has effectively been reduced to two alternatives. First is the Alvarez scenario, which proposes that the K-T extinction was a sudden event triggered by a single extraterrestrial bullet. Second is the gradualist view, which proposes that the asteroid impact was accompanied by two other global-scale perturbations (volcanism and decreasing sea-level), and that it was only this combination of factors acting in concert that decimated the end-Mesozoic biosphere.

Paleontologists of the gradualist ilk have argued that dinosaurs (and certain other groups) were already on their way out well before the K-T "big bang" occurred. Unfortunately, the fossil record of dinosaurs is relatively poor for the last stage of the Mesozoic and only one place on Earth — a small swath of badlands in the Western Interior of North America — has been investigated in detail. Several authors have argued that the latest Cretaceous Hell Creek fauna, as it's called (best known from eastern Montana), was depauperate relative to earlier dinosaur faunas. In particular, comparisons are often been made with the ca. 75 million year old Late Cretaceous Dinosaur Park Formation of southern Alberta, which has yielded a bewildering array of herbivorous and carnivorous dinosaurs.

For a long time, I regarded myself a card-carrying member of the gradualist camp. However, at least two lines of evidence have persuaded me to change my mind and join the ranks of the sudden-extinction-precipitated-by-an-asteroid group. 

First is a growing database indicating that the terminal Cretaceous world was not stressed to the breaking point, awaiting arrival of the coup de grâce from outer space. With regard to dinosaurs in particular, recent work has demonstrated that the Hell Creek fauna was much more diverse than previously realized. Second, new and improved stratigraphic age controls for dinosaurs and other Late Cretaceous vertebrates in the Western Interior indicate that ecosystems like those preserved the Dinosaur Park Formation were not nearly as diverse as previously supposed. 

Instead, many dinosaur species appear to have existed for relatively short durations (< 1 million years), with some geologic units preserving a succession of relatively short-lived faunas. So, even within the well sampled Western Interior of North America (let alone the rest of the world, for which we currently have little hard data), I see no grounds for arguing that dinosaurs were undergoing a slow, attritional demise. Other groups, like plants, also seem to have been doing fine in the interval leading up to that fateful day 65.5 million years ago. Finally, extraordinary events demand extraordinary explanations, and it does not seem parsimonious to make an argument for a lethal cascade of agents when compelling evidence exists for a single agent capable of doing the job on its own.

So yes, as far as I'm concerned (at least for now), the asteroid did it.

When I was 21, I began working for the Union of Concerned Scientists (UCS) in Cambridge Massachusetts. I was still an undergraduate at the time, planning on doing a brief research stint in energy policy before finishing college and heading to graduate school in physics. That "brief research stint" lasted about seven years, off and on, and I never did make it to graduate school. But the experience was instructive nevertheless.

When I started at UCS in the 1970s, nuclear power safety was a hot topic, and I squared off in many debates against nuclear proponents from utility companies, nuclear engineering departments, and so forth regarding reactor safety, radioactive wastes, and the viability of renewable energy alternatives. The next issue I took on for UCS was the nuclear arms race, which was equally polarized. (The neocons of that day weren't "neo" back then; they were just cons.) As with nuclear safety, there was essentially no common ground between the two sides. Each faction was invariably trying to do the other in, through oral rhetoric and tendentious prose, always looking for new material to buttress their case or undermine that of their opponents.

Even though the organization I worked for was called the Union of Concern Scientists, and even though many of the staff members there referred to me as a "scientist" (despite my lack of academic credentials), I knew that what I was doing was not science. (Nor were the many physics PhD's in arms control and energy policy doing science either.) In the back of my head, I always assumed that "real science" was different — that scientists are guided by facts rather than by ideological positions, personal rivalries, and whatnot.

In the decades since, I've learned that while this may be true in many instances, oftentimes it's not. When it comes to the biggest, most contentious issues in physics and cosmology — such as the validity of inflationary theory, string theory, or the multiverse/landscape scenario — the image of the objective truth seeker, standing above the fray, calmly sifting through the evidence without preconceptions or prejudice, may be less accurate than the adversarial model of our justice system. Both sides, to the extent there are sides on these matters, are constantly assembling their briefs, trying to convince themselves as well as the jury at large, while at the same time looking for flaws in the arguments of the opposing counsel.

This fractionalization may stem from scientific intuition, political or philosophical differences,  personal grudges, or pure academic competition. It's not surprising that this happens, nor is it necessarily a bad thing. In fact, it's my impression that this approach works pretty well in the law and in science too. It means that, on the big things at least, science will be vetted; it has to withstand scrutiny, pass muster.

But it's not a cold, passionless exercise either. At its heart, science is a human endeavor, carried out by people. When the questions are truly ambitious, it takes a great personal commitment to make any headway — a big investment in energy and in emotion as well. I know from having met with many of the lead researchers that the debates can get heated, sometimes uncomfortably so. More importantly, when you're engaged in an epic struggle like this — trying, for instance, to put together a theory of broad sweep — it may be difficult, if not impossible, to keep an "open mind" because you may be well beyond that stage, having long since cast your lot with a particular line of reasoning. And after making an investment over the course of many years, it's natural to want to protect it. That doesn't mean you can't change your mind — and I know of several cases where this has occurred — but, no matter what you do, it's never easy to shift from forward to reverse.

Although I haven't worked as a scientist in any of these areas, I have written about many of the "big questions" and know how hard it is to get all the facts lined up so that they fit together into something resembling an organic whole. Doing that, even as a mere scribe, involves periods of single-minded exertion, and during that process the issues can almost take on a life of their own, at least while you're actively thinking about them. Before long, of course, you've moved onto the next story and the excitement of the former recedes. As the urgency fades, you start wondering why you felt so strongly about the landscape or eternal inflation or whatever it was that had taken over your desk some months ago.

It's different, of course, for researchers who may stake out an entire career — or at least big chunks thereof — in a certain field.  You're obliged to keep abreast of all that's going on of note, which means one's interest is continually renewed. As new data comes in, you try to see how it fits in with the pieces of the puzzle you're already grappling with. Or if something significant emerges from the opposing camp, you may instinctively seek out the weak spots, trying to see how those guys messed up this time.

It's possible, of course, that a day may come when, try as you might, you can't find the weak spots in the other guy's story. After many attempts and an equal number of setbacks, you may ultimately have to accede to the view of an intellectual, if not personal, rival. Not that you want to but rather because you can't see any way around it. On the one hand, you might chalk it up as a defeat, something that will hopefully build character down the road. But in the grand scheme of things, it's more of a victory — a sign that sometimes our adversarial system of science actually works.

I used to believe that the ethos of science, the very nature of science, guaranteed the ethical behavior of its practitioners. As a student and a young researcher, I could not conceive of cheating, claiming credit for the work of others, or fabricating data. Among my mentors and my colleagues, I saw no evidence that anyone else believed otherwise. And I didn't know enough of the history of my own subject to be aware of ethical lapses by earlier scientists. There was, I sensed, a wonderful purity to science. Looking back, I have to count naiveté as among my virtues as a scientist.

Now I have changed my mind, and I have changed it because of evidence, which is what we scientists are supposed to do. Various examples of cheating, some of them quite serious, have come to light in the last few decades, and misbehaviors in earlier times have been reported as well. Scientists are, as the saying goes, "only human," which, in my opinion, is neither an excuse nor an adequate explanation. Unfortunately, scientists are now subjected to greater competitive pressures, financial and otherwise, than was typical when I was starting out. Some — a few — succumb.

We do need to teach ethics as essential to the conduct of science, and we need to teach the simple lesson that in science crime doesn't pay. But above all, we need to demonstrate by example that the highest ethical standards should, and often do, come naturally.

When the phenomenon of "mirror neurons" that fire both when a specific action is perceived and when it is intended was first reported, I was impressed by the research but skeptical about its significance. Specifically, I doubted, and continue to doubt, that these circuits are specific adaptations for purposes of various higher mental functions. I saw mirror neurons as simple units in circuits that represent specific actions, oblivious as to whether they had been viewed when performed by someone else, or represented as the goal of one's own intended action (so-called reafference copy). Why have two separate representations of the same thing when one will do? Activity elsewhere in the brain represents who the agent is, self or another. I still think that this is the most economical interpretation. But from a broader perspective I have come to realize that mirror neurons are not only less than meets the eye but also more. Instead of being a specific specialization, they play their role as part of a fundamental design characteristic of the brain; that is, when percepts are activated, relevant intentions, memories and feelings automatically fall into place.

External event are "represented" by the patterns of neuronal activity that they engender in sensory cortex. These representations also incorporate the actions that the percepts potentially afford. This "enactive coding" or "common coding" of input implies a propensity in the observer's brain to imitate the actions of others (consciously or unconsciously). This propensity need not result in overt imitation. Prefrontal cortex is thought to hold these impulses to imitate in check. Nonetheless, the fact that these action circuits have been activated, lowers their threshold by subtle increments as the experience in question is repeated over and over again, and the relative loading of synaptic weights in brain circuitry become correspondingly adjusted. Mirror neurons exemplify this type of functioning, which extends far beyond individual circuits to all cell assemblies that can form representations,

That an individual is likely to act in the same ways that others act is seen in the documented benefit for sports training of watching experts perform. "Emotional contagion" occurs when someone witnesses the emotional expressions of another person and therefore experiences that mood state oneself. People's viewpoints can subtly and unconsciously converge when their patterns of neural activation match, in the total absence of argument or attempts at persuasion. When people entrain with each other in gatherings, crowds, assemblies and mobs, diverse individual views reduce into a unified group viewpoint. An extreme example of gradual convergence might be the "Stockholm Syndrome"; captives gradually adopt the worldview of their captors. In general, interacting with others makes one converge to their point of view (and vice versa). Much ink has been spilled on the topic of the lamentable limitations of human rationality. Here is one reason why.

People's views are surreptitiously shaped by their experiences, and rationality comes limping after, downgraded to rationalization. Once opinions are established, they engender corresponding anticipations. People actively seek those experiences that corroborate their own self-serving expectations. This may be why as we grow older, we become ever more like ourselves. Insights become consolidated and biases reinforced when one only pays attention to confirming evidence. Diverse mutually contradictory "firm convictions" are the result. Science does take account of the negative instance as well as the positive instance. It therefore has the potential to help us understand ourselves, and each other.

If I am correct in my changed views as to what mirror neurons stand for and how representation routinely merges perception, action, memory and affect into dynamic reciprocal interaction, these views would have a bearing on currently disputed issues. Whether an effect is due to the brain or the environment would be moot if environmental causes indeed become brain causes, as the impressionable brain resonates with changing circumstances. What we experience contributes mightily to what we are and what we become. An act of kindness has consequences for the beneficiary far beyond the immediate benefit. Acts of violence inculcate violence and contaminate the minds of those who stand by and watch. Not only our private experiences, but also the experiences that are imposed on us by the media, transform our predispositions, whether we want them to or not. The implications for child rearing are obvious, but the same implications apply beyond childhood to the end of personal time.

What people experience indeed changes their brain, for better and for worse. In turn, the changed brain changes what is experienced. Regardless of its apparent stability over time, the brain is in constant flux, and constantly remodels. Heraclitus was right: "You shall not go down twice to the same river". The river will not be the same, but for that matter, neither will you. We are never the same person twice. The past is etched into the neural network, biasing what the brain is and does in the present. William Faulkner recognized this: "The past is never dead. In fact, it's not even past".

I used to think that a modern, democratic society had to be a scientific society. After all, the scientific revolution and the American Revolution were forged in the same flames of the enlightenment. Naturally, I thought, a society that embraces the freedom of thought and expression of a democracy would also embrace science.

However, when I first started reporting on science, I quickly realized that science didn't spring up naturally in the fertile soil of the young American democracy. Americans were extraordinary innovators — wonderful tinkerers and engineers — but you can count the great 19th century American physicists on one hand and have two fingers left over. The United States owes its scientific tradition to aristocratic Europe's universities (and to its refugees), not to any native drive.

In fact, science clashes with the democratic ideal. Though it is meritocratic, it is practiced in the elite and effete world of academe, leaving the vast majority of citizens unable to contribute to it in any meaningful way. Science is about freedom of thought, yet at the same time it imposes a tyranny of ideas.

In a democracy, ideas are protected. It's the sacred right of a citizen to hold — and to disseminate — beliefs that the majority disagrees with, ideas that are abhorrent, ideas that are wrong. However, scientists are not free to be completely open minded; a scientist stops becoming a scientist if he clings to discredited notions. The basic scientific urge to falsify, to disprove, to discredit ideas clashes with the democratic drive to tolerate and protect them.

This is why even those politicians who accept evolution will never attack those politicians who don't; at least publicly, they cast evolutionary theory as a mere personal belief. Attempting to squelch creationism smacks of elitism and intolerance — it would be political suicide. Yet this is exactly what biologists are compelled to do; they exorcise falsehoods and drive them from the realm of public discourse.

We've been lucky that the transplant of science has flourished so beautifully on American soil. But I no longer take it for granted that this will continue; our democratic tendencies might get the best of us in the end.

What is the nature of mathematics? Becoming a mathematician in the 1960s, I swallowed hook, line, and sinker the Platonistic philosophy dominant at the time, that the objects of mathematics (the numbers, the geometric figures, the topological spaces, and so forth) had a form of existence in some abstract ("Platonic") realm. Their existence was independent of our existence as living, cognitive creatures, and searching for new mathematical knowledge was a process of explorative discovery not unlike geographic exploration or sending out probes to distant planets.

I now see mathematics as something entirely different, as the creation of the (collective) human mind. As such, mathematics says as much about we ourselves as it does about the external universe we inhabit. Mathematical facts are not eternal truths about the external universe, which held before we entered the picture and will endure long after we are gone. Rather, they are based on, and reflect, our interactions with that external environment.

This is not to say that mathematics is something we have freedom to invent. It's not like literature or music, where there are constraints on the form but writers and musicians exercise great creative freedom within those constraints. From the perspective of the individual human mathematician, mathematics is indeed a process of discovery. But what is being discovered is a product of the human (species)-environment interaction.

This view raises the fascinating possibility that other cognitive creatures in another part of the universe might have different mathematics. Of course, as a human, I cannot begin to imagine what that might mean. It would classify as "mathematics" only insofar as it amounted to that species analyzing the abstract structures that arose from their interactions with their environment.

This shift in philosophy has influenced the way I teach, in that I now stress social aspects of mathematics. But when I'm giving a specific lecture on, say, calculus or topology, my approach is entirely platonistic. We do our mathematics using a physical brain that evolved over hundreds of thousands of years by a process of natural selection to handle the physical and more recently the social environments in which our ancestors found themselves. As a result, the only way for the brain to actually do mathematics is to approach it "platonistically," treating mathematical abstractions as physical objects that exist.

A platonistic standpoint is essential to doing mathematics, just as Cartesian dualism is virtually impossible to dispense with in doing science or just plain communicating with one another ("one another"?). But ultimately, our mathematics is just that: our mathematics, not the universe's.

For most of my career, I believed that the bedrock of physical reality lay with the laws of physics — magnificent, immutable, transcendent, universal, infinitely-precise mathematical relationships that rule the universe with as sure a hand as that of any god. And I had orthdoxy on my side, for most of my physicist colleagues also believe that these perfect laws are the levitating superturtle that holds up the mighty edifice we call nature, as disclosed through science. About three years ago, however, it dawned on me that such laws are an extraordinary and unjustified idealization.

How can we be sure that the laws are infinitely precise? How do we know they are immutable, and apply without the slightest change from the beginning to the end of time? Furthermore, the laws themselves remain unexplained. Where do they come from? Why do they have the form that they do? Indeed, why do they exist at all? And if there are many possible such laws, then, as Stephen Hawking has expressed it, what is it that "breathes fire" into a particular set of laws and makes a universe for them to govern?

So I did a U turn and embraced the notion of laws as emergent with the universe rather than stamped on it from without like a maker's mark. The "inherent" laws I now espouse are not absolute and perfect, but are instrinsically fuzzy and flexible, although for almost all practical purposes we don't notice the tiny flaws.

Why did I change my mind? I am not content to merely accept the laws of physics as a brute fact. Rather, I want to explain the laws, or at least explain the form they have, as part of the scientific enterprise. One of the oddities about the laws is the well known fact that they are weirdly well-suited to the emergence of life in the universe. Had they been slightly different, chances are there would be no sentient beings around to discover them.

The fashionable explanation for this — that there is a multiplicity of laws in a multiplicity of parallel universes, with each set of laws fixed and perfect within its host universe — is a nice try, but still leaves a lot unexplained. And simply saying that the laws "just are" seems no better than declaring "God made them that way."

The orthodox view of perfect physical laws is a thinly-veiled vestige of monothesim, the reigning world view that prevailed at the birth of modern science. If we want to explain the laws, however, we have to abandon the theological legacy that the laws are fixed and absolute, and replace them with the notion that the states of the world and the laws that link them form a dynamic interdependent unity.

Growing up as a young proto-scientist, I was always strongly anti-establishmentarian, looking forward to overthrowing the System as our generation's new Galileo.  Now I spend a substantial fraction of my time explaining and defending the status quo to outsiders.  It's very depressing.

As an undergraduate astronomy I was involved in a novel and exciting test of Einstein's general relativity — measuring the precession of orbits, just like Mercury in the Solar System, but using massive eclipsing binary stars.  What made it truly exciting was that the data disagreed with the theory!  (Which they still do, by the way.)  How thrilling is it to have the chance to overthrow Einstein himself?  Of course there are more mundane explanations — the stars are tilted, or there is an invisible companion star perturbing their orbits, and these hypotheses were duly considered.  But I wasn't very patient with such boring possibilities — it was obvious to me that we had dealt a crushing blow to a cornerstone of modern physics, and the Establishment was just too hidebound to admit it.

Now I know better.  Physicists who are experts in the field tend to be skeptical of experimental claims that contradict general relativity, not because they are hopelessly encumbered by tradition, but because Einstein's theory has passed a startlingly diverse array of experimental tests.  Indeed, it turns out to be almost impossible to change general relativity in a way that would be important for those binary stars, but which would not have already shown up in the Solar System.  Experiments and theories don't exist in isolation — they form a tightly connected web, in which changes to any one piece tend to reverberate through various others.

So now I find myself cast as a defender of scientific orthodoxy — from classics like relativity and natural selection, to modern wrinkles like dark matter and dark energy.  In science, no orthodoxy is sacred, or above question — there should always be a healthy exploration of alternatives, and I have always enjoyed inventing new theories of gravity or cosmology, keeping in mind the variety of evidence in favor of the standard picture.  But there is also an unhealthy brand of skepticism, proceeding from ignorance rather than expertise, which insists that any consensus must flow from a reluctance to face up to the truth, rather than an appreciation of the evidence.  It's that kind of skepticism that keeps showing up in my email.  Unsolicited.

Heresy is more romantic than orthodoxy.  Nobody roots for Goliath, as Wilt Chamberlain was fond of saying.  But in science, ideas tend to grow into orthodoxy for good reasons.  They fit the data better than the alternatives.  Many casual heretics can't be bothered with all the detailed theoretical arguments and experimental tests that support the models they hope to overthrow — they have a feeling about how the universe should work, and are convinced that history will eventually vindicate them, just as it did Galileo.

What they fail to appreciate is that, scientifically speaking, Galileo overthrew the system from within.  He understood the reigning orthodoxy of his time better than anyone, so he was better able to see beyond it.  Our present theories are not complete, and nobody believes they are the final word on how Nature works.  But finding the precise way to make progress, to pinpoint the subtle shift of perspective that will illuminate a new way of looking at the world, will require an intimate familiarity with our current ideas, and a respectful appreciation of the evidence supporting them. 

Being a heretic can be fun; but being a successful heretic is mostly hard work.

I used to believe that we could understand psychology at different levels of analysis, and events at any one of the levels could be studied independently of events at the other levels. For example, one could study events at the level of the brain (and seek answers in terms of biological mechanisms), the level of the person (and seek answers in terms of the contents of thoughts, beliefs, knowledge, and so forth), or the level of the group (and seek answers in terms of social interactions). This approach seemed reasonable; the strategy of "divide and conquer" is a cornerstone in all of science, isn't it? In fact, virtually all introductory psychology textbooks are written as if events at the different levels are largely independent, with separate chapters (that only rarely include cross-references to each other) on the brain, perception, memory, personality, social psychology, and so on. 

I've changed my mind. I don't think it's possible to understand events at any one level of analysis without taking into account what occurs at other levels. In particular, I'm now convinced that at least some aspects of the structure and function of the brain can only be understood by situating the brain in a specific cultural context. I'm not simply saying that the brain has evolved to function in a specific type of environment (an idea that forms a mainstay of evolutionary psychology and some areas of computer vision, where statistics of the natural environment are used to guide processing). Rather, I'm saying that to understand how any specific brain functions, we need to understand how that person was raised, and currently functions, in the surrounding culture. 

Here's my line of reasoning. Let's begin with a fundamental fact: The genes, of which we have perhaps only some 30,000, cannot program us to function equally effectively in every possible environment. Hence, evolution has licensed the environment to set up and configure each individual's brain, so that it can work well in that context. For example, consider stereovision. We all know about stereo in audition; the sound from each of two loudspeakers has slightly different phases, so the listener's brain glues them together to provide the sense of an auditory panorama. Something similar is at work in vision. In stereovision, the slight disparity in the images that reach the two eyes are a cue for how far away objects are. If you're focused on an object directly in front of you, your eyes will converge slightly. Aside from the exact point of focus, the rest of the image will strike slightly different places on the two retinas (at the back of the eye, which converts light into neural impulses), and the brain uses the slight disparities to figure out how far away something is. 
            
There are two important points here. First, this stereo process — of computing depth on the basis of the disparities in where images strike the two retinas — depends on the distance between the eyes. And second, and this is absolutely critical, there's no way to know at the moment of conception how far apart a person's eyes are going to be, because that depends on bone growth — and bone growth depends partly on the mother's diet and partly on the infant's diet. 
            
So, given that bone growth depends partly on the environment, how could the genes set up stereovision circuits in the brain? What the genes did is really clever: Young children (peaking at about age 18 months) have more connections among neurons than do adults; in fact, until about eight years old, children have about twice as many neural connections as they do as adults. But only some of these connections provide useful information. For example, when the infant reaches, only the connections from some neurons will correctly guide reaching. The brain uses a process called pruning to get rid of the useless connections. The connections that turn out to work, with the distance between the eyes the infant happens to have, would not be the ones that would work if the mother did not have enough calcium, or the infant hadn't had enough of various dietary supplements. 
            
This is a really elegant solution to the problem that the genes can't know in advance how far apart the eyes will be. To cope with this problem, the genes overpopulate the brain, giving us options for different environments (where the distance between eyes and length of the arms are part of the brain's "environment," in this sense), and then the environment selects which connections are appropriate. In other words, the genes take advantage of the environment to configure the brain. 

This overpopulate-and-select mechanism is not limited to stereovision. In general, the environment sets up the brain (above and beyond any role it may have had in the evolution of the species), configuring it to work well in the world a person inhabits. And by environment I'm including everything outside the brain — including the social environment. For example, it's well known that children can learn multiple languages without an accent and with good grammar, if they are exposed to the language before puberty. But after puberty, it's very difficult to learn a second language so well. Similarly, when I first went to Japan, I was told not even to bother trying to bow, that there were something like a dozen different bows and I was always going to "bow with an accent" — and in my case the accent was so thick that it was impenetrable.  
            
The notion is that a variety of factors in our environment, including in our social environment, configure our brains. It's true for language, and I bet it's true for politeness as well as a raft of other kinds of phenomena. The genes result in a profusion of connections among neurons, which provide a playing field for the world to select and configure so that we fit the environment in which we inhabit. The world comes into our head, configuring us. The brain and its surrounding environment are not as separate as they might appear.  

This perspective leads me to wonder whether we can assume that the brains of people living in different cultures process information in precisely the same ways. Yes, people the world over have much in common (we are members of the same species, after all), but even small changes in the wiring may lead us to use the common machinery in different ways. If so, then people from different cultures may have unique perspectives on common problems, and be poised to make unique contributions toward solving such problems. 

Changing my mind about the relationship between events at different levels of analysis has led me to change fundamental beliefs. In particular, I now believe that understanding how the surrounding culture affects the brain may be of more than merely "academic interest."

At age 10 in 1950, one of the department stores had a pneumatic tube system for moving receipts and money from counters to the cashier's office. I loved this and tried to figure out how it worked The clerks in the store knew all about it. "Vacuum", they said, "Vacuum sucks the canisters, just like your mom's vacuum cleaner". But how does it work, I asked? "Vacuum", they said, "Vacuum, does it all". This was what adults called "an explanation"!

So I took apart my mom's Hoover vacuum cleaner to find out how it worked. There was an electric motor in there, which I had expected, but the only other thing in there was a fan! How could a fan produce a vacuum, and how could it suck?

We had a room fan and I looked at it more closely. I knew that it worked like the propeller of an airplane, but I'd never thought about how those worked. I picked up a board and moved it. This moved air just fine. So the blades of the propeller and the fan were just boards that the motor kept on moving to push air.

But what about the vacuum? I found that a sheet of paper would stick to the back of the fan. But why? I "knew" that air was supposed to be made up of particles too small to be seen. So it was clear why you got a gust of breeze by moving a board — you were knocking little particles one way and not another. But where did the sucking of the paper on the fan and in the vacuum cleaner come from?

Suddenly it occurred to me that the air particles must be already moving very quickly and bumping into each other. When the board or fan blades moved air particles away from the fan there were less near the fan and the already moving particles would have less to bump into and would thus move towards the fan. They didn't know about the fan, but they appeared to.

The "suck" of the vacuum cleaner was not a suck at all. What was happening is that things went into the vacuum cleaner because they were being "blown in" by the air particles' normal movement, which were not being opposed by the usual pressure of air particles inside the fan!

When my physiologist father came home that evening I exclaimed "Dad, the air particles must be moving at least a hundred miles an hour!". I told him what I'd found out and he looked in his physics book. In there was a formula to compute the speed of various air molecules at various temperatures. It turned out that at room temperature ordinary air molecules were moving much faster than I had guessed: more like 1500 miles an hour! This completely blew my mind!

Then I got worried because even small things were clearly not moving that fast going into the vacuum cleaner (nor in the pneumatic tubes). By putting my hand out the window of the car I could feel that the air was probably going into the vacuum cleaner closer to 50 or 60 miles an hour. Another conversation with my Dad led to two ideas (a) the fan was probably not very efficient at moving particles away, and (b) the particles themselves were going in every direction and bumping into each other (this is why it takes a while for perfume from an open bottle to be smelled across a room.

This experience was a big deal for me because I had thought one way using a metaphor and a story about "sucking", and then I suddenly thought just the opposite because of an experiment and non-story thinking. The world was not as it seemed! Or as most adults thought and claimed! I never trusted "just a story" again.

I have, falteringly and with various intermediary about-faces and caveats, changed my mind about human spaceflight. I am of the generation to have had its childhood imagination stoked by the sight of Apollo missions on the television — I can't put hand on heart and say I remember the Eagle landing, but I remember the sights of the moon relayed to our homes. I was fascinated by space and only through that, by way of the science fiction that a fascination with space inexorably led to, by science. And astronauts were what space was about.

I was not, as I grew older, uncritical of human spaceflight — I remember my anger at the Challenger explosion, my sense that if people were going to die, it should be for something grander than just another shuttle mission. But I was still struck by its romance, and by the way its romance touched some of the unlikeliest people. By all logic The Economist should have been, when I worked there, highly dubious about the aspirations of human spaceflight, as it is today. But the then editor would hear not a word against the undertaking, at least not against its principle. With some relief at this I became while the magazine's science editor a sort of critical apologist — critical of the human space programme there actually was, but sensitive to the possibility that a better space programme was possible.

I bought into, at least at some level, the argument that a joint US-Russian programme offered advantages in terms of aerospace employment in the former USSR. I bought into the argument that continuity of effort was needed — that so much would be lost if a programme was dismantled it might not be possible to reassemble it. I bought into the crucial safety-net argument — that it would not be possible to cancel the US programme anyway, so strong were the interests of the military industrial complex and so broad, if shallow, the support of the public. (Like the Powder River, a mile wide, an inch deep and rolling uphill all the way from Texas.) And I could see science it would offer that was unavailable by any other means.

Now, though, I can no longer find much to respect in those arguments. US Russian cooperation seems to have bought little benefit. The idea of continuous effort seems at best unproven — and indeed perhaps worth checking. Leaving a technology fallow for a few decades and coming back with new people, tools and mindsets is not such a bad idea. And at least one serious presidential candidate is talking about actually freezing the American programme, cancelling the shuttle without in the short term developing its successor. Whether Obama will get elected or be willing or able to carry through the idea remains to be seen — but if politicians are talking like this the "it will never happen so why worry" argument becomes far more suspect.

And the crucial idea (crucial to me) that human exploration of Mars might answer great questions about life in the universe no longer seems as plausible or as likely to pay off in my lifetime as once it did. I increasingly think that life in a Martian deep biosphere if there is any, will be related to earth life and teach us relatively little that's new. At the same time it will be fiendishly hard to reach without contamination. Mars continues to fascinate me — but it has ever less need of a putative future human presence in order to do so.

My excitement at the idea of life in the universe — excitement undoubtedly spurred by Apollo and the works of Clarke, Heinlein and Roddenberry that followed on from it in my education — is now more engaged with exoplanets, to which human spaceflight is entirely irrelevant (though post-human spaceflight may be a different kettle of lobsters). If we want to understand the depth of the various relations between life and planets, which is what I want to understand, it is by studying other planets with vibrant biospheres, as well as this one, that we will do so. A world with a spartan $100 billion moonbase but no ability to measure spectra and lightcurves from earthlike planets around distant stars is not the world for me.

In general, I try to avoid arguing from my own interests. But in this case it seems to me that all the other arguments against human spaceflight are so strong that to be against it merely meant realising that an atavistic part of me had failed to understand what those interests are. I'm interested in how life works on astronomical scales, and that interest has nothing to do, in the short term, with human spaceflight. And I see no reason beyond my own interests to suggest that it is something worth spending so much money on. It does not make the world a better place in any objective way that can be measured, or in any subjective way that compels respect.

It is possibly also the case that seeing human spaceflight reduced to a matter of suborobital hops for the rich, or even low earth orbit hotels, has hardened my heart further against it. I hope this is not a manifestation of the politics of envy, though I fear that in part it could be.

I have changed my mind about technology.

I used to take a dim view of technology. One should live one's life in a simple, low-tech fashion, I thought. No cell phone, keep off the computer, don't drive. No nukes, no remote control, no DVD, no TV. Walk, read, think — that was the proper path to follow.

What a fool I was! A dozen years ago or so, by some bizarre accident, I became a professor of Mechanical Engineering at MIT. I had never had any training, experience, or education in engineering. My sole claim to engineering expertise was some work on complex systems and a few designs for quantum computers. Quantum-mechanical engineering was in its early days then, however, and MIT needed a quantum mechanic. I was ready to answer the call.

It was not my fellow professors who converted me to technology, uber-techno-nerds though they were. Indeed, my colleagues in Mech. E. were by and large somewhat suspicious of me, justifiably so. I was wary of them in turn, as one often is of co-workers who are hugely more knowledgeable than one is oneself. (Outside of the Mechanical Engineering department, by contrast, I found large numbers of kindred souls: MIT was full of people whose quanta needed fixing, and as a certified quantum mechanic, I was glad to oblige.) No, it was not the brilliant technologists who filled the faculty lunchroom who changed my mind. Rather, it was the students who had come to have me teach them about engineering who taught me to value technology.

Your average MIT undergraduate is pretty technologically adept. In the old days, freshmen used to arrive MIT having disassembled and reassembled tractors and cars; slightly later on, they arrived having built ham radios and guitar amplifiers; more recently, freshmen and fresh women were showing up with a scary facility with computers. Nowadays, few of them have used a screwdriver (except maybe to install some more memory in their laptop), but they are eager to learn how robots work, and raring to build one themselves.

When I stepped into my first undergraduate classroom, a controls laboratory, I knew just about as little about how to build a robot as the nineteen and twenty year olds who were expectantly sitting, waiting for me to teach them how. I was terrified. Within a half an hour, the basis for my terror was confirmed. Not only did I know as little as the students, in many cases I knew significantly less: about of the quarter of the students knew demonstrably more about robotics than I, and were happy to display their knowledge. I emerged from the first lab session a sweaty mess, having managed to demonstrate my ignorance and incompetence in a startling variety of ways.

I emerged  from the second lab session a little cooler. There is no better way to learn, and learn fast, than to teach. Humility actually turns out to have its virtues, too. It turns out to be rather fun to admit one's ignorance, if that admission takes the form of an appeal to the knowledge of all assembled. In fact, it turned out that, either through my training in math and physics, or through a previous incarnation, I possessed more intuitive knowledge of control theory than I had any right to, given my lack of formal education on the subject. Finally, no student is more empowered than the one who has just correctly told her professor that he is wrong, and showed him why her solution is the right one.

In the end, the experience of teaching the technology that I did not know was one of the most intellectually powerful of my life. In my mental ferment of trying to learn the material faster and deeper than my students, I began to grasp concepts and ways of looking at the world, of whose existence I had no previous notion. One of the primary features of the lab was a set of analog computers, boxy things festooned with dials and plugs, and full of amplifiers, capacitors, and resistors, that were used to simulate, or construct an analog, of the motors and loads that we were trying to control. In my feverish attempt to understand analog computers, I constructed model for a quantum-mechanical analog computer that would operate at the level of individual atoms. This model resulted in one of my best scientific papers. In the end, scarily enough, my student evaluations gave me the highest possible marks for knowledge of the material taught.

And technology? Hey, it's not so bad. When it comes to walking in the rain, Goretex and fleece beat oilskin and wool hollow. If we're not going to swamp our world in greenhouse gases, we damn well better design dramatically more efficient cars and power plants. And if I could contribute to technology by designing and helping to build quantum computers and quantum communication systems, so much the better. Properly conceived and constructed technology does not hinder the simple life, but helps it.

OK. So I was wrong about technology. What's my next misconception? Religion? God forbid.

In public appearances about global warming, even these days, I often hear: "I don't believe in global warming" and I then typically get asked why I do "when all the evidence is not in". "Global warming is not about beliefs", I typically retort, "but an accumulation of evidence over decades so that we can now say the vast preponderance of evidence — and its consistency with basic climate theory — supports global warming as well established, not that all aspects are fully known, an impossibility in any complex systems science".

But it hasn't always been that way, especially for me at the outset of my career in 1971, when I co-authored a controversial paper calculating that cooling effects from a shroud of atmospheric dust and smoke — aerosols — from human emissions at a global scale appeared to dominate the opposing warming effect of the growing atmospheric concentrations of the greenhouse gas carbon dioxide. Measurements at the time showed both warming and cooling emissions were on the rise, so a calculation of the net balance was essential — though controlling the aerosols made sense with or without climate side effects since they posed — and still pose — serious health effects on vulnerable populations.  In fact for the latter reason laws to clean up the air in most rich countries were just getting negotiated about that time.

When I traveled the globe in the early 1970s to explain our calculations, what I slowly learned from those out there making measurements was that two facts had only recently come to light, and together they appeared to make me consider flipping sign from cooling to warming as the most likely climatic change direction from humans using the atmosphere as a free sewer to dump some of our volatile industrial and agricultural wastes.  These facts were that human-injected aerosols, which we assumed were global in scale in our cooling calculation — were in fact concentrated primarily in industrial regions and bio-mass burning areas of the globe — about 20% of the Earth's surface, whereas we already knew that CO2 emissions are global in extent and about half of the emitted CO2 lasts for a century or more in the air.

But there were new facts that were even more convincing: not only is CO2 an important human-emitted greenhouse gas, but so too were methane, nitrous oxide and chlorofluorocarbons (many of the latter gases now banned because they also deplete stratospheric ozone) , and that together with CO2, these other greenhouse gasses were an enhanced global set of warming factors. On the other hand, aerosols were primarily regional in extent and could not thus overcome the warming effects of the combined global scale greenhouse gases.

I was very proud to have published in the mid-1970s what was wrong with my early calculations well before the so-called "contrarians" — climate change deniers still all too prevalent even today — understood the issues, let alone incorporated these new facts into updated models to make more credible projections. Of course, today the dominance of warming over cooling agents is now well established in the climatology community, but our remaining inability to be very precise over how much warming the planet can expect to have to deal with is in large part still an uncertainty over the partially counteracting cooling effects of aerosols — enough to offset a significant, even if largely unknown, amount of the warming. So although we are very confident in the existence of human-caused warming in the past several decades from greenhouse gases, we are still are working hard to pin down much more precisely how much aerosols offset this warming. Facts on that offset still lag the critical need to estimate better our impacts on climate before they become potentially irreversible.

The sad part of this story is not about science, but the misinterpretation of it in the political world. I still have to endure polemical blogs from contrarian columnists and others about how, as one put it in a grand polemic: "Schneider is an environmentalist for all temperatures" — citing my early calculations. This famous columnist somehow forgot to bring up the later-corrected (by me) faulty assumptions, nor mention that the 1971 calculation was based on not-yet-gathered facts. Simply getting the sign wrong was cited, ipso facto in this blog, as somehow damning of my current credibility. 

Ironically, inside the scientific world, this switch of sign of projected effects is viewed as precisely what responsible scientists must do when the facts change. Not only did I change my mind, but published almost immediately what had changed and how that played out over time. Scientists have no crystal ball, but we do have modeling methods that are the closest approximation available. They can't give us truth, but they can tell us the logical consequences of explicit assumptions. Those who update their conclusions explicitly as facts evolve are much more likely to be a credible source than those who stick to old stories for political consistency. Two cheers for the scientific method!

I changed my mind about online community this year.

I co-edit a blog that attracts a large number of daily visitors, many of whom have something to say back to us about whatever we write or produce in video. When our audience was small in the early days, interacting was simple: we tacked a little href tag to an open comments thread at the end of each post: Link, Discuss. No moderation, no complication, come as you are, anonymity's fine. Every once in a while, a thread accumulated more noise than signal, but the balance mostly worked.

But then, the audience grew. Fast. And with that, grew the number of antisocial actors, "drive-by trolls," people for whom dialogue wasn't the point. It doesn't take many of them to ruin the experience for much larger numbers of participants acting in good faith.

Some of the more grotesque attacks were pointed at me, and the new experience of being on the receiving end of that much personally-directed nastiness was upsetting. I dreaded hitting the "publish" button on posts, because I knew what would now follow.

The noise on the blog grew, the interaction ceased to be fun for anyone, and with much regret, we removed the comments feature entirely.

I grew to believe that the easier it is to post a drive-by comment, and the easier it is to remain faceless, reputation-less, and real-world-less while doing so, the greater the volume of antisocial behavior that follows. I decided that no online community could remain civil after it grew too large, and gave up on that aspect of internet life.

My co-editors and I debated, we brainstormed, we observed other big sites that included some kind of community forum or comments feature. Some relied on voting systems to "score" whether a comment is of value — this felt clinical, cold, like grading what a friend says to you in conversation. Dialogue shouldn't be a beauty contest. Other sites used other automated systems to rank the relevance of a speech thread. None of this felt natural to us, or an effective way to prevent the toxic sludge buildup. So we stalled for years, and our blog remained more monologue than dialogue. That felt unnatural, too.

Finally, this year, we resurrected comments on the blog, with the one thing that did feel natural. Human hands.

We hired a community manager, and equipped our comments system with a secret weapon: the "disemvoweller." If someone's misbehaving, she can remove all the vowels from their screed with one click. The dialogue stays, but the misanthrope looks ridiculous, and the emotional sting is neutralized.

Now, once again, the balance mostly works. I still believe that there is no fully automated system capable of managing the complexities of online human interaction — no software fix I know of. But I'd underestimated the power of dedicated human attention.

Plucking one early weed from a bed of germinating seeds changes everything. Small actions by focused participants change the tone of the whole. It is possible to maintain big healthy gardens online. The solution isn't cheap, or easy, or hands-free. Few things of value are.

I have learned quantum mechanics as a young man, first from the book by Dirac, and then form a multitude of other excellent textbooks. The theory appeared bizarre and marvelous, but it made perfectly sense to me. The world, as Shakespeare put it, is "strange and admirable", but it is coherent. I could not understand why people remained unhappy with such a clear and rational theory. In particular, I could not understand why some people lost their time on a non-problem called the "interpretation of quantum mechanics".

I have remained of this opinion for many years. Then I moved to Pittsburgh, to work in the group of Ted Newman, great relativist and one of the most brilliant minds in the generation before mine. While there, the experiments made by the team of Alain Aspect Aspect at Orsay, in France, which confirmed spectacularly some of the strangest predictions of quantum mechanics, prompted a long period of discussion in our group. Basically, Ted claimed that quantum theory made no sense. I claimed that it does perfectly, since it is able to predict unambiguously the probability distribution of any conceivable observation.

Long time has passed, and I have changed my mind. Ted's arguments have finally convinced me: I was wrong, and he was right. I have slowly came to realize that in its most common textbook version, quantum mechanics makes sense as a theory of a small portion of the universe, a "system", only under the assumption that something else in the universe fails to obey quantum mechanics. Hence it becomes self contradictory, in its usual version, if we take it as a general description of all physical systems of the universe. Or, at least, there is still something key to understand, with respect to it.

This change of opinion has motivated me to start of a novel line of investigation, which I have called "relational quantum mechanics". It has also affected substantially my work in quantum gravity, taking me to consider a different sort of observable quantities as natural probes of quantum spacetime.

I am now sure that quantum theory has still much to tell us about the deep structure of the world. Unless I'll change my mind again, of course.

When reporters interviewed me in the 70's and 80's about the possibilities for Artificial Intelligence I would always say that we would have machines that are as smart as we are within my lifetime. It seemed a safe answer since no one could ever tell me I was wrong. But I no longer believe that will happen. One   reason is that  I am a lot older and we are barely closer to creating smart machines. 

I have not soured on AI. I still believe that we can create very intelligent machines. But I no longer believe that those machines will be like us. Perhaps it was the movies that led us to believe that we would have intelligent robots as companions. (I was certainly influenced early on by 2001.)  Certainly most AI researchers believed that creating machines that were our intellectual equals or better was a real possibility. Early AI workers sought out intelligent behaviors to focus on, like chess or problem solving, and tried to build machines that could equal human beings in those same endeavors. While this was an understandable approach it was, in retrospect, wrong-headed.     Chess playing is not really a typical intelligent human activity. Only some of us are good at it, and it seems to entail a level of cognitive processing that while impressive seems quite at odds with what makes humans smart. Chess players are methodical planners. Human beings are not.

Humans are constantly learning.  We spend years learning some seemingly simple stuff. Every new experience changes what we know and how we see the world. Getting reminded of our pervious experiences helps us process new experiences better than we did the time before. Doing that depends upon an unconscious indexing method that all people learn to do without quite realizing they are learning it. We spend twenty years (or more) learning how to speak properly and learning how to make good decisions and establish good relationships. But we tend to not know what we know. We can speak properly without knowing how we do it. We don't know how we comprehend. We just do.

All this poses a problem for AI. How can we imitate what humans are doing when humans don't know what they are doing when they do it? This conundrum led to a major failure in AI, expert systems, that relied upon rules that were supposed to characterize expert knowledge. But, the major characteristic of experts is that they get faster when they know more, while more rules made systems slower. The idea that rules were not at the center of intelligent systems meant that the flaw was relying upon specific consciously stated knowledge instead of trying to figure out what people meant when they said they just knew it when they saw it, or they had a gut feeling.

People give reasons for their behaviors but they are typically figuring that stuff out after the fact. We reason non-consciously and explain rationally later. Humans dream. There obviously is some important utility in dreaming.  Even if we don't understand precisely what the consequences of dreaming are, it is safe to assume that it is an important part of our unconscious reasoning process that drives our decision making. So, an intelligent machine would have to dream because it needed to, and would have to have intuitions that proved to be good insights, and it would have to have a set of driving goals that made it see the world in a way that a different entity with different goals would not. In other words it would need a personality, and not one that was artificially installed but one that came with the territory of what is was about as an intelligent entity.

What AI can and should build are intelligent special purpose entities. (We can call them Specialized Intelligences or SI's.) Smart computers will indeed be created. But they will arrive in the form of SI's, ones that make lousy companions but know every shipping accident that ever happened and why (the shipping industry's SI) or as an expert on sales (a business world SI.)   The sales SI, because sales is all it ever thought about, would be able to recite every interesting sales story that had ever happened and the lessons to be learned from it. For some salesman about to call on a customer for example, this SI would be quite fascinating. We can expect a foreign policy SI that helps future presidents learn about the past in a timely fashion and helps them make decisions because it knows every decision the government has ever made and has cleverly indexed them so as to be able to apply what it knows to current situations. 

So AI in the traditional sense, will not happen in my lifetime nor in my grandson's lifetime. Perhaps a new kind of machine intelligence will one day evolve and be smarter than us, but we are a really long way from that.

Near the end of his life Charles Darwin invited for lunch at Down House Dr Ludwig Büchner, President of the Congress of the International Federation of Freethinkers, and Edward Aveling, a self-proclaimed and active atheist.  The invitation was at their request.  Emma Darwin, devout as ever, was appalled by the thought of entertaining such guests and at table insulated herself from the atheists with an old family friend, the Rev. Brodie Innes, on her right and with her grandson and his friends on her left.  After lunch Darwin and his son Frank smoked cigarettes with the two visitors in Darwin's old study.  Darwin asked them with surprising directness: "Why do you call yourselves atheists?"  He said that he preferred the word agnostic.  While Darwin agreed that Christianity was not supported by evidence, he felt that atheist was too aggressive a term to describe his own position.

For many years what had been good enough for Darwin was good enough for me.  I too described myself as an agnostic.  I had been brought up in a Christian culture and some of the most rational humanists I knew were believers.  I loved the music and art that had been inspired by a belief in God and saw no hypocrisy in participating in the great carol services held in the Chapel of King's College Cambridge. I did not accept the views of some of my scientific colleagues that the march of science has disposed of religion.  The wish that I and many biologists had to understand biological evolution was not the same as the wish had by those with deep religious conviction to understand the meaning of life.

I had, however, led a sheltered life and had never met anybody who was aggressively religious.  I hated, of course, what I had read about the ugly fanaticism of all forms of religious fundamentalism or what I had seen of it on television.  However, such wickedness did not seem to be simply correlated with religious belief since many non-believers were just as totalitarian in their behaviour as the believers.   My unwillingness to be involved in religious debates was shaken at a grand dinner party.  The woman sitting next to me asked me what I did and I told her that I am a biologist.  "Oh well," she said, "then we have plenty to talk about, because I believe that every word of the Bible is literally true."  My heart sank.

As things turned out, we didn't have a great deal to talk about because she wasn't going to be persuaded by any argument that I could throw at her.  She did not seem to wonder about the inconsistencies between the gospels of the New Testament or those between the first and second chapters of Genesis.  Nor was she concerned about where Cain's wife came from?  The Victorians were delicate about such matters and were not going to entertain the thought that Cain married an unnamed sister or, horrors, that his own mother bore his children, his grand children and so on down the line of descendants until other women became available.  Nevertheless, the devout Victorians were obviously troubled by the question and they speculated on the existence of pre-Adamite people, angels probably, who would have furnished Cain with his wife.

My creationist dinner companion was not worried by such trivialities and dismissed my lack of politesse as the problem of a scientist being too literal.  However, being too literal was not my problem, it was hers and those of her fellow creationists.   She was hoist on her own petard.  In any event, it was quite simply stupid to try to take on science on its own terms by appealing to the intelligence implicit in natural design.  Science provides orderly methods for examining the natural world.  One of those methods is to develop theories that integrate as much as possible of what we know about the phenomena encompassed by the theory.  The theories provide frameworks for testing the characteristics of the world — and though some theorists may not wish to believe it, their theories are eminently disposable.  Facts are widely shared opinions and, every so often the consensus breaks — and minds change.  Nevertheless it is crying for the moon to hope that the enormous bodies of thought that have been built up about cosmology, geology and biological evolution are all due to fall apart.  No serious theologian would rest his or her beliefs on such a hope. If faith rests on the supposed implausibility of a current scientific explanation, it is vulnerable to the appearance of a plausible one.  To build on such sand is a crass mistake.

Not long after that dreadful dinner, Richard Dawkins wrote to me to ask whether I would publicly affirm my atheism.  I could see no reason why not.  One of the clear definitions of an atheist is a lack of a belief in a God.  That certainly described my position, even though I am disinclined to attack the beliefs of the sincere and thoughtful people with strong religious beliefs whom I continue to meet.  I completed the questionnaire that Richard had sent to me.  I had changed my mind. A dear friend, Peter Lipton, who died suddenly in November 2007, had been assiduous in maintaining Jewish customs in his own home and in his public defence of Israel.  After he died I was surprised to discover that he described himself as a religious atheist.  I should not have been surprised.

I am an anthropologist who has traveled to many places and met many different kinds of people. I try to know what it is like to be someone very different from me in order to better understand what it means to be human. But it is only in the last few years that my thinking has deeply changed on what drives major differences between animal and human behavior, such as willingness to kill and die for a cause.

I once thought that individual cognition and personality, influences from broad socio-economic factors, and degree of devotion to religious or political ideology were determinant. Now I see friendship and others aspects of small group dynamics, especially acting together, trumping most everything else.

Here's an anecdote that kick-started me thinking about this.

While preparing a psychological experiment on limits of rational choice with Muslim mujahedin on the Indonesian Island of Sulawesi, I noticed tears welling in my traveling companion and bodyguard, Farhin (who had earlier hosted 9-11 mastermind Khalid Sheikh Muhammed in Jakarta and helped to blow up the Philippines' ambassador's residence). Farhin had just heard of a young man recently been killed in a skirmish with Christian fighters.

"Farhin," I asked, "you knew the boy?"

"No," he said, "but he was only in the jihad a few weeks. I've been fighting since Afghanistan [late 1980s] and still not a martyr."

I tried consoling with my own disbelief, "But you love your wife and children."

"Yes," he nodded sadly, "God has given this, and I must have faith in His way."

I had come to the limits of my understanding of the other. There was something in Farhin that was incalculably different from me yet almost everything else was not.

"Farhin, in all those years, after you and the others came back from Afghanistan, how did you stay a part of the Jihad?" I asked.

I expected him to tell me about his religious fervor and devotion to a Great Cause.

"The (Indonesian) Afghan Alumni never stopped playing soccer together," he replied matter-of-factly, "that's when we were closest together in the camp." He smiled, "except when we went on vacation to fight the communists, we played soccer and remained brothers."

Maybe people don't kill and die simply for a cause. They do it for friends — campmates, schoolmates, workmates, soccer buddies, body-building buddies, pin-ball buddies — who share a cause. Some die for dreams of jihad — of justice and glory — but nearly all in devotion to a family-like group of friends and mentors, of "fictive kin."

Then it became embarrassingly obvious: it is no accident that nearly all religious and political movements express allegiance through the idiom of the family — Brothers and Sisters, Children of God, Fatherland, Motherland, Homeland, and the like. Nearly all such movements require subordination, or at least assimilation, of any real family (genetic kinship) to the larger imagined community of "Brothers and Sisters." Indeed, the complete subordination of biological loyalty to ideological loyalty for the Ikhwan, the "Brotherhood" of the Prophet, is Islam's original meaning, "Submission."

My research team has analyzed every attack by Farhin and his friends, who belong to Southeast Asia's Jemmah Islamiyah (JI). I have interviewed key JI operatives (including co-founder, Abu Bakr Ba'asyir) and counterterrorism officials who track JI. Our data show that support for suicide actions is triggered by moral outrage at perceived attacks against Islam and sacred values, but this is converted to action as a result of small world factors. Out of millions who express sympathy with global jihad, only a few thousand show willingness to commit violence. They tend to go to violence in small groups consisting mostly of friends, and some kin. These groups arise within specific "scenes": neighborhoods, schools (classes, dorms), workplaces and common leisure activities (soccer, mosque, barbershop, café, online chat-rooms).

Three other examples:

1. In Al Qaeda, about 70 percent join with friends, 20 percent with kin. Our interviews with friends of the 9/11 suicide pilots reveal they weren't "recruited" into Qaeda. They were Middle Eastern Arabs isolated in a Moroccan Islamic community in a Hamburg suburb. Seeking friendship, they started hanging out after mosque services, in local restaurants and barbershops, eventually living together when they self-radicalized. They wanted to go to Chechnya, then Kosovo, only landing in a Qaeda camp in Afghanistan as a distant third choice. 

2. Five of the seven plotters in the 2004 Madrid train bombing who blew themselves up when cornered by police grew up in the tumble-down neighborhood of Jemaa Mezuaq in Tetuan, Morocco. In 2006, at least five more young Mezuaq men went to Iraq on "martyrdom missions." One in the Madrid group was related to one in the Iraq group by marriage; each group included a pair of brothers. All went to the same elementary school, all but one to the same high school. They played soccer as friends, went to the same mosque, mingled in the same cafes. 

3. Hamas's most sustained suicide bombing campaign in 2003 (Hamas suspended bombings in 2004) involved seven soccer buddies from Hebron's Abu Katila neighborhood, including four kin (Kawasmeh clan).

Social psychology tends to support the finding that "groupthink" often trumps individual volition and knowledge, whether in our society or any other. But for Americans bred on a constant diet of individualism the group is not where one generally looks for explanation. This was particularly true for me, but the data caused me to change my mind.

Throughout my academic career – when I was studying the relationship between psychoanalysis and society and when I moved to the social and psychological studies of technology – I've seen myself as a cultural critic. I don't mention this to stress how lofty a job I put myself in, but rather that I saw the job as theoretical in its essence. Technologists designed things; I was able to offer insights about the nature of people's connections to them, the mix of feelings in the thoughts, how passions mixed with cognition. Trained in psychoanalysis, I didn't see my stance as therapeutic, but it did borrow from the reticence of that discipline. I was not there to meddle. I was there to listen and interpret. Over the past year, I've changed my mind: our current relationship with technology calls forth a more meddlesome me.

In the past, because I didn't criticize but tried to analyze, some of my colleagues found me complicit with the agenda of technology-builders. I didn't like that much, but understood that this was perhaps the price to pay for maintaining my distance, as Goldilock's wolf would say, "the better to hear them with." This year I realized that I had changed my stance. In studying reactions to advanced robots, robots that look you in the eye, remember your name, and track your motions, I found more people who were considering such robots as friends, confidants, and as they imagined technical improvements, even as lovers. I became less distanced. I began to think about technological promiscuity. Are we so lonely that we will really love whatever is put in front of us?

I kept listening for what stood behind the new promiscuity – my habit of listening didn't change – and I began to get evidence of a certain fatigue with the difficulties of dealing with people. A female graduate student came up to me after a lecture and told me that she would gladly trade in her boyfriend for a sophisticated humanoid robot as long as the robot could produce what she called "caring behavior." She told me that "she needed the feeling of civility in the house and I don't want to be alone." She said: "If the robot could provide a civil environment, I would be happy to help produce the illusion that there is somebody really with me." What she was looking for, she told me, was a "no-risk relationship" that would stave off loneliness; a responsive robot, even if it was just exhibiting scripted behavior, seemed better to her than an demanding boyfriend. I thought she was joking. She was not.

In a way, I should not have been surprised. For a decade I had studied the appeal of sociable robots. They push our Darwinian buttons. They are programmed to exhibit the kind of behavior we have come to associate with sentience and empathy, which leads us to think of them as creatures with intentions, emotions, and autonomy. Once people see robots as creatures, they feel a desire to nurture them. With this feeling comes the fantasy of reciprocation. As you begin to care for these creatures, you want them to care about you.

And yet, in the past, I had found that people approached computational intelligence with a certain "romantic reaction." Their basic position was that simulated thinking might be feeling but simulated feeling was never feeling and simulated love was never love. Now, I was hearing something new. People were more likely to tell me that human beings might be "simulating" their feelings, or as one woman put it: "How do I know that my lover is not just simulating everything he says he feels?" Everyone I spoke with was busier than ever on with their e-mail and virtual friendships. Everyone was busier than ever with their social networking and always-on/always-on-you PDAs. Someone once said that loneliness is failed solitude. Could no one stand to be alone anymore before they turned to a device? Were cyberconnections paving the way to think that a robotic one might be sufficient unto the day? I was not left contemplating the cleverness of engineering but the vulnerabilities of people.

Last spring I had a public exchange in which a colleague wrote about the "I-Thou" dyad of people and robots and I could only see Martin Buber spinning in his grave. The "I" was the person in the relationship, but how could the robot be the "Thou"? In the past, I would have approached such an interchange with discipline, interested only in the projection of feeling onto the robot. But I had taken that position when robots seemed only an evocative object for better understanding people's hopes and frustrations. Now, people were doing more than fantasizing. There was a new earnestness. They saw the robot in the wings and were excited to welcome it onstage.

It seemed no time at all that a book came out called Love and Sex with Robots and a reporter from Scientific American was interviewing me about the psychology of robot marriage. The conversation was memorable and I warned my interviewer that I would use it as data. He asked me if my opposition to people marrying robots put me in the same camp as those who oppose the marriage of lesbians or gay men. I tried to explain that just because I didn't think people could marry machines didn't mean that I didn't think that any mix of people with people was fair play. He accused me of species chauvinism. Wasn't this the kind of talk that homophobes once used, not considering gays as "real" people? Right there I changed my mind about my vocation. I changed my mind about where my energies were most needed. I was turning in my card as a cultural critic the way I had always envisaged that identity. Now I was a cultural critic. I wasn't neutral; I was very sad.

Ten years ago, I wrote:

For ninety-nine percent of human existence, people lived as foragers in small nomadic bands. Our brains are adapted to that long-vanished way of life, not to brand-new agricultural and industrial civilizations. They are not wired to cope with anonymous crowds, schooling, written language, government, police, courts, armies, modern medicine, formal social institutions, high technology, and other newcomers to the human experience.

And:

Are we still evolving? Biologically, probably not much. Evolution has no momentum, so we will not turn into the creepy bloat-heads of science fiction. The modern human condition is not conducive to real evolution either. We infest the whole habitable and not-so-habitable earth, migrate at will, and zigzag from lifestyle to lifestyle. This makes us a nebulous, moving target for natural selection. If the species is evolving at all, it is happening too slowly and unpredictably for us to know the direction. (How the Mind Works)

Though I stand by a lot of those statements, I've had to question the overall assumption that human evolution pretty much stopped by the time of the agricultural revolution. When I wrote these passages, completion of the Human Genome Project was several years away, and so was the use of statistical techniques that test for signs of selection in the genome. Some of these searches for "Darwin's Fingerprint," as the technique has been called, have confirmed predictions I had made. For example, the modern version gene associated with language and speech has been under selection for several hundred thousand years, and has even been extracted from a Neanderthal bone, consistent with my hypothesis (with Paul Bloom) that language is a product of gradual natural selection. But the assumption of no-recent-human-evolution has not.

New results from the labs of Jonathan Pritchard, Robert Moyzis, Pardis Sabeti, and others have suggested that thousands of genes, perhaps as much as ten percent of the human genome, have been under strong recent selection, and the selection may even have accelerated during the past several thousand years. The numbers are comparable to those for maize, which has been artificially selected beyond recognition during the past few millennia.

If these results hold up, and apply to psychologically relevant brain function (as opposed to disease resistance, skin color, and digestion, which we already know have evolved in recent millennia), then the field of evolutionary psychology might have to reconsider the simplifying assumption that biological evolution was pretty much over and done with 10-000 — 50,000 years ago.

And if so, the result could be evolutionary psychology on steroids. Humans might have evolutionary adaptations not just to the conditions that prevailed for hundreds of thousands of years, but also to some of the conditions that have prevailed only for millennia or even centuries. Currently, evolutionary psychology assumes that any adaptation to post-agricultural ways of life are 100% cultural.

Though I suspect some revisions will be called for, I doubt they will be radical, for two reasons. One is that many aspects of the human (and ape) environments have been constant for a much longer time than the period in which selection has recently been claimed to operate. Examples include dangerous animals and insects, toxins and pathogens in spoiled food and other animal products, dependent children, sexual dimorphism, risks of cuckoldry and desertion, parent-offspring conflict, risk of cheaters in cooperation, fitness variation among potential mates, causal laws governing solid bodies, presence of conspecifics with minds, and many others. Recent adaptations would have to be an icing on this cake -- quantitative variations within complex emotional and cognitive systems.

The other is the empirical fact that human races and ethnic groups are psychologically highly similar, if not identical. People everywhere use language, get jealous, are selective in choosing mates, find their children cute, are afraid of heights and the dark, experience anger and disgust, learn names for local species, and so on. If you adopt children from a technologically undeveloped part of the world, they will fit in to modern society just fine. To the extent that this is true, there can't have been a whole lot of uneven psychological evolution postdating the split among the races 50-100,000 years ago (though there could have been parallel evolution in all the branches).

I have been a true disciple of kin-selection theory ever since I discovered the wonders of social evolution as a young graduate student. Kin selection theory emphasizes the importance of relatedness (i.e. kin) in the evolution of social behavior. The essence of social living lies in sharing tasks amongst group members; for example some individuals may end up monopolizing reproduction (dominants or queens), whilst others defend or forage for the group (helpers or altruists). The key to understanding how sociality evolves rests on finding a watertight explanation for altruism. Why should any individual sacrifice their reproductive rights in order to help another individual reproduce?

When groups consist of families, there is an intuitive basis for the evolution of altruism. Helping relatives, with whom I share many of my genes, is potentially a lucrative strategy for passing my genes on to future generations. This reasoning led W.D. Hamilton to his theory of inclusive fitness, or kin selection, in 1964: a social action evolves if the benefit (b) weighted by the relatedness (r) between group members exceeds the costs (c) of that action (i.e. br>c). Evolution is satisfyingly parsimonious, so it is only natural that an apparently complicated thing like sociality can be explained in such simple terms.

I am certain I speak for many students of sociality in being eternally grateful to Hamilton in providing such an elegant theory with such clear predictions to test. Off we go, armed with Hamilton’s Rule to settle our quest for understanding what makes an animal social. There are three things to measure: relatedness between group members (or actors and recipients), costs (to the actor in being altruistic) and benefits (to the recipient in receiving help). Happily, the molecular revolution has brought gene-level analytical tools to behavioral ecologists, allowing relatedness to be quantified accurately. Costs and benefits are more problematic to quantify, as they might vary over an individual’s life-time. Relatedness, therefore could be a fast-track route to securing the secrets of sociality in a kin-selected context.

The social Hymenoptera (ants, bees and wasps) are an excellent group for studying sociality because they live in large groups and have a peculiar genetic sex-determination system (haplodiploidy), engendering high levels of relatedness. If relatedness predisposes any animal to be social, it will be the Hymenoptera. As an altruist in a social insect colony there are several ways by which you could favor your most closely related group members. You could selectively feed sibling brood that share the same parents as you. Or, you could eat the eggs laid by your siblings in preference to those laid by your mother (the queen). On planning an elopement from the homestead to start a new colony, you might choose full-sisters as your companions rather than a random relative. The predictions are elegant, simple and depend on the kin structure of a specific colony.

With insect cadavers mounting up in university freezers all over the world, we raced to test these predictions. The results were disheartening: worker wasps headed by multiply mated mother queens were not maximizing their indirect fitness by laying heaps of parthenogenetic male eggs; worker ants were unable to optimally manipulate the brood sex ratios (and hence their inclusive fitness) in relation to how many times their mother had mated; social wasps were feeding larvae in regard to their need rather than relatedness; swarming wasps were indiscriminate in who they founded new colonies with.

On the back of robust experiments like these, I have changed my mind about relatedness being the primary dictator of social evolution. Insects are unable to discriminate relatedness on an individual level. Instead, relatedness may act at the colony/population level, or simply in distinguishing kin from non-kin. This make sense. An individual-level kin discrimination mechanism is vulnerable to invasion by an occasional nepotist, who would favor its closest relatives over others. As the gene for nepotism spreads, the variation on which the kin-discrimination is based (e.g. chemical or visual cues) will disappear and individuals will no longer be able to tell kin from non-kin, let alone full siblings from half siblings: sociality breaks down. We knew this long before many of the kin-discrimination experiments were done, but optimism perseveres until enough evidence pervades.

Does this mean kin selection theory is wrong? Absolutely not! The reason for this is that relatedness is only one (albeit important) component of kin selection theory. The key is likely to be the interaction of a high (and variable) benefit to cost ratio from helping, and a positive relatedness between actors and recipients: relatedness does not have to be high for altruism to evolve, it just needs to be greater than the population average. I still believe you cannot hope to understand sociality unless you put relatedness at the top of your list. But, we need to complement the huge amount of data generated by the molecular hamster wheel with some serious estimates of the costs and benefits of social actions.

The words "science" and "technology," or equivalently the words "research" and "development," are used in the same breath so readily that one might easily presume that they are joined at the hip: that their goals are indistinguishable, and that those who are good at one are, if not necessarily equally good at the other, at least quite good at evaluating the quality of work in the other. I grew up with this assumption, but the longer I work at the interface between science and technology the more I find myself having to accept that it is false — that most, scientists are rather poor at the type of thinking that identifies efficient new ways to get things done, and that, likewise, technologists are mostly not terribly good at identifying efficient ways to find things out.

I've come to feel that there are several reasons underlying this divide.

A major one is the divergent approaches of scientists and technologists to the use of evidence. In basic research, it is exceptionally easy to be seduced by one's data — to see a natural interpretation of it and to overlook the existence of other, comparably economical interpretations of it that lead to dramatically different conclusions. It therefore makes sense for scientists to give the greatest weight, when evaluating the evidence for and against a given hypothesis, to the most direct observational or experimental evidence at hand.

Technologists, on the other hand, succeed best when they stand back from the task before them, thinking laterally about ways in which ostensibly irrelevant techniques might be applied to solve one or another component of the problem. The technologist's approach, when applied to science, is likely to result all too often in wasted time, as experiments are performed that contain too many departures from previous work to allow the drawing of firm conclusions either way concerning the hypothesis of interest.

Conversely, applying the scientist's methodology to technological endeavours can also result in wasted time, resulting from overly small steps away from techniques already known to be futile, like trying to fly by flapping mechanical wings.

But there's another difference between the characteristic mindsets of scientists and technologists, and I've come to view it as the most problematic. Scientists are avowedly "curiosity-driven" rather than "goal-directed" — they are spurred by the knowledge that, throughout the history of civilisation, innumerable useful technologies have become possible not through the stepwise execution of a predefined plan, but rather through the purposely undirected quest for knowledge, letting a dynamically-determined sequence of experiments lead where it may.

That logic is as true as it ever was, and any technologist who doubts it need only examine the recent history of science to change his mind. However, it can be — and, in my view, all too often is — taken too far. A curiosity-driven sequence of experiments is useful not because of the sequence, but because of the technological opportunities that emerge at the end of the sequence. The sequence is not an end in itself. And this is rather important to keep in mind. Any scientist, on completing an experiment, is spoilt for choice concerning what experiment to do next — or, more prosaically, concerning what experiment to apply for funding to do next.

The natural criterion for making this choice is the likelihood that the experiment will generate a wide range of answers to technologically important questions, thereby providing new technological opportunities. But an altogether more frequently adopted criterion, in practice, is that the experiment will generate a wide range of new questions — new reasons to do more experiments. This is only indirectly useful, and I believe that in practice it is indeed less frequently useful than programs of research designed with one eye on the potential for eventual technological utility.

Why, then, is it the norm? Simply because it is the more attractive to those who are making these decisions — the curiosity-driven scientists (whether the grant applicants or the grant reviewers) themselves. Curiosity is addictive: both emotionally and in their own enlightened self-interest, scientists want reasons to do more science, not more technology. But as a society we need science to be as useful as possible, as quickly as possible, and this addiction slows us down.

At the end of The Structure of Scientific Revolutions, Thomas Kuhn suggested that it is reasonable to trust the general consensus of experts instead of a revolutionary idea, even when the revolutionary idea is consistent with a finding that could not be explained by  the general consensus.  He reasoned that the general consensus was reached by drawing together countless bits of evidence, and even though it could not explain everything, it had passed a gauntlet to which the revolutionary idea had not yet been subjected. 

Kuhn's idea seemed sufficiently plausible to lead me to generally trust the consensus of experts in disciplines outside my area of expertise.  I still think that it is wise to trust the experts when their profession has a good understanding of the processes under consideration.   This situation applies to experts on car maintenance, for example, because cars were made by people who shared their knowledge about the function of car parts, and top notch car mechanics learn this information.  It also applies generally to the main principles of mechanical and electrical engineering, biology, physics, and chemistry, because these principles are tested directly or indirectly by the countless studies. 

I am becoming convinced, however, that the opposite view is often true when the expert opinion pertains to the unknown: the longer and more widespread the accepted wisdom has been accepted, the more hesitant we should be to trust it, especially if the experts  have been studying the question intensively during this period of acceptance and contradictory findings or logic have been presented.  The reason is simple.  If an explanation has been widely and broadly accepted and convincing evidence still cannot be mustered, then it is quite reasonable to expect that the experts are barking up the wrong, albeit cherished, trees.  That is, its acceptance has more to do with the limitations of intellectual ingenuity than with evidence. 

This argument provides a clear guideline for allocating trust to experts: distrust expert opinion in accordance with what is not known about the subject.  This guideline is, of course, difficult to apply because one has to first ascertain whether a discipline actually has valid answers for a given area of inquiry.  Consider something as simple as a sprained ankle.  Evolutionary considerations suggest that the inflammation and pain associated with sprained ankles are adaptive responses to promote healing, and that suppressing them would be detrimental to long-term functionality of the joint.   I have searched the literature to find out whether any evidence indicates that treatment of sprained ankles with ice, compression, anti-inflammatories, and analgesics promotes or hinders healing and long-term functionality of the joint. In particular, I have been looking for comparisons of treated individuals with untreated controls.  I have not found any and am coming to the conclusion that this widely advocated expert opinion is a detrimental holdover from ancient Greek medicine, which often confused the return of the body to a more healthy appearance with the return of the body to a state of health.  

More generally, I am coming to the disquieting realization that much of scientific opinion and even more of medical opinion falls into the murky area circumscribed by a lack of adequate knowledge about the processes at hand.  This means that I must invoke broadly the guideline to distrust expert opinion in proportion to the lack of knowledge in the area. Although this has made me more objectionable, it has also been of great value intellectually and practically, as when, for example, I sprain my ankle.

One of my most basic assumptions about the relationship between mental effort and brain function has begun to crumble. Here's why.

My earliest research interests as a psychologist were in the ways mental training can shape biological systems.  My doctoral dissertation was a psychophysiological study of meditation as an intervention in stress reactivity; I found (as have many others since) that the practice of meditation seems to speed the rate of physiological recovery from a stressor.

My guiding assumptions included the standard premise that the mind-body relationship operates according to orderly, understandable principles.  One such might be called the "dose-response" rule, that the more time put into a given method of training, the greater the result in the targeted biological system.  This is a basic correlate of neuroplasticity, the mechanism through which repeated experience shapes the brain.

For example, a string of research has now established that more experienced meditators recover more quickly from stress-induced physiological arousal than do novices. Nothing remarkable there.  The dose-response rule would predict this is so. Thus brain imaging studies show that the spatial areas of London taxi drivers become enhanced during the first six months they spend driving around that city's winding streets; likewise, the area for thumb movement in the motor cortex becomes more robust in violinists as they continue to practice over many months.

This relationship has been confirmed in many varieties of mental training. A seminal 2004 article in the Proceedings of the National Academy of Science found that, compared to novices, highly adept meditators generated far more high-amplitude gamma wave activity — which reflects finely focused attention — in areas of the prefrontal cortex while meditating.

The seasoned meditators in this study — all Tibetan lamas — had undergone cumulative levels of mental training akin to the amount of lifetime sports practice put in by Olympic athletes: 10,000 to 50,000 hours. Novices tended to increase gamma activity by around 10 to 15 percent in the key brain area, while most experts had increases on the order of 100 percent from baseline. What caught my eye in this data was not this difference between novices and experts (which might be explained in any number of ways, including a self-selection bias), but rather a discrepancy in the data among the group of Olympic-level meditators.

Although the experts' average boost in gamma was around 100 percent, two lamas were "outliers": their gamma levels leapt 700 to 800 percent. This goes far beyond an orderly dose-response relationship — these jumps in high-amplitude gamma activity are the highest ever reported in the scientific literature apart from pathological conditions like seizures. Yet the lamas were voluntarily inducing this extraordinarily heightened brain activity for just a few minutes at a time — and by meditating on "pure compassion," no less.

I have no explanation for this data, but plenty of questions. At the higher reaches of contemplative expertise, do principles apply (as the Dalai Lama has suggested in dialogues with neuroscientists) that we do not yet grasp? If so, what might these be? In truth, I have no idea. But these puzzling data points have pried open my mind a bit as I've had to question what had been a rock-solid assumption of my own.

In a 2007 radio advertisement, former NYC mayor Rudy Giuliani said, "I had prostate cancer, five, six years ago. My chances of surviving prostate cancer — and thank God I was cured of it — in the United States: 82 percent. My chances of surviving prostate cancer in England: only 44 percent under socialized medicine." Giuliani was lucky to be living in New York, and not in York — true?

In World Brain (1938), H. G. Wells predicted that for an educated citizenship in a modern democracy, statistical thinking would be as indispensable as reading and writing. At the beginning of the 21st century, we have succeeded in teaching millions how to read and write, but many of us still don't know how to reason statistically — how to understand risks and uncertainties in our technological world.

Giuliani is a case in point. One basic concept that everyone should understand is the 5-year survival rate. Giuliani used survival rates from the year 2000, where 49 Britons per 100,000 were diagnosed of prostate cancer, of which 28 died within 5 years — about 44 percent. Is it true that his chances of surviving cancer are about twice as high in what Giuliani believes is the best health care system in the world? Not at all. Survival rates are not the same as mortality rates. The U.S. has in fact about the same prostate cancer mortality rate as the U.K. But far more Americans participate in PSA screening (although its effect on mortality reduction has not been proven). As a consequence, more Americans are diagnosed of prostate cancer, which skyrockets the 5-year survival rate to more than 80%, although no life is saved. Screening detects many "silent" prostate cancers that the patient would have never noticed during his lifetime. Americans live longer with the diagnosis, but they do not live longer. Yet many Americans end up incontinent or impotent for the rest of their lives, due to unnecessary aggressive surgery or radiation therapy, believing that their life has been saved.

Giuliani is not an exception to the prevailing confusion about how to evaluate health statistics. For instance, my research shows that 80% to 90% of German physicians do not understand what a positive screening test means — such as PSA, HIV, or mammography — and most do not know how to explain the patient the potential benefits and harms. Patients however falsely assume that their doctors know and understand the relevant medical research. In most medical schools, education in understanding health statistics is currently lacking or ineffective.

The bare fact of statistical illiteracy among physicians, patients, and politicians is still not well known, much less addressed, made me pessimistic about the chances of any improvement. Statistical illiteracy in health matters turns the ideals of informed consent and shared decision-making into science fiction. Yet I have begun to change my mind. Here are a few reasons why I'm more optimistic.

Consider the concept of relative risks. You may have heard that mammography screening reduces breast cancer mortality by 25%! Impressive, isn't it? Many believe that if 100 women participate, the life of 25 will be saved. But don't be taken in again. The number is based on studies that showed that out of every 1,000 women who do not participate in mammography screening, 4 will die of breast cancer within about 10 years, whereas among those who participate in screening this number decreases to 3. This difference can be expressed as anabsolute risk, that is, one out of every 1,000 women dies less of breast cancer, which is a clear and transparent.  But it also can be phrased in terms of a relative risk: a 25% benefit. I have asked hundreds of gynecologists to explain what this benefit figure means. The good news is that two-thirds understood that 25% means 1 in 1,000. Yet one third overestimated the benefits by one or more orders of magnitudes. Thus, better training in medical school is still wanted.

What makes me optimistic is the reaction of some 1,000 gynecologists I have trained in understanding risks and uncertainties as part of their continuing education. First, learning how to communicate risks was a top topic on their wish list. Second, despite the fact that most had little statistical training, they learned quickly. Consider the situation of a woman who tests positive in a screening mammogram, and asks her doctor whether she has cancer for certain, or what her chances are.  She has a right to get the best answer from medical science: Out of ten women who test positive, only one has breast cancer, the other nine cases are false alarms. Most women are never informed about this relevant fact, and react with panic and fear. Mammography is not a very reliable test. Before the training, the majority of gynecologists mistakenly believed that about 9 out of 10 women who test positive have cancer, as opposed to only one! After the training, however, almost all physicians understood how to read this kind of health statistics. That's real progress, and I didn't expect so much, so soon.

What makes me less optimistic is resistance to transparency in health from government institutions. A few years ago, I presented the program of transparent risk communication to the National Cancer Institute in Bethesda. Two officials took me aside afterwards and lauded the program for its potential to make health care more rational. I asked if they intended to implement it. Their answer was no. Why not? As they explained, transparency in this form was bad news for the government — a benefit of only 0.1% instead of 25% would make poor headlines for the upcoming election! In addition, their board was appointed by the presidential administration, for which transparency in health care is not a priority.

Win some, lose some. But I think the tide is turning. Statistics may still be woefully absent from most school curricula, including medical schools. That could soon change in the realm of health, however, if physicians and patients make common cause, eventually forcing politicians to do their homework.

As a teenager growing up in the rural American Midwest, I played in a Christian rock band. We wrote worship songs, with texts on religious themes, and experienced the jubilation and transport of the music as a visitation by the Holy Spirit. Then one day, as my faith was beginning to waiver, I wrote a song with an explicitly nonreligious theme. To my surprise I discovered that when I performed it, I was overcome by the same feelings, and it dawned on me that maybe what we had experienced all along was our own spirits, that what had called to us was the power of music itself.

In truth, I wasn't thinking through much at the time. Later, as a graduate student of philosophy, I did start to think a lot about science and ethics, and I began to undergo a parallel shift of outlook. Having embraced a thoroughly naturalistic, materialistic worldview, I wondered: If everything is just matter, how could anything really matter? How could values be among the objective furniture of the universe? It is not as if anyone expected physicists to discover, alongside electrons, protons, and neutrons, a new fundamental moral particle--the moron?--which would show up in high magnitudes whenever people did nice things.

Then there was J. L. Mackie's famous argument from "queerness": objective values would have to be such that merely coming to appreciate them would motivate you to pursue them. But given everything we know about how ordinary natural facts behave (they seem to ask nothing of us), how could there possibly be states of affairs with this strange to-be-pursuedness built into them, and how could we come to appreciate them?

At the same time, I was taken in by the promises found in some early sociobiology that a new evolutionary science of human nature would supplant empty talk about objective values. As Michael Ruse once put it, "morality is just an aid to survival and reproduction," and so "any deeper meaning is illusory." Niceness may seem self-evidently right to us, but things could easily have been the other way around, had nastiness paid off more often for our ancestors.

I have since been convinced that I was looking at all of this in the wrong way. Not only are values a part of nature; we couldn't avoid them if we tried.

There is no doubt that had we evolved differently, we would value different things. However, that alone does not show that values are subjective. After all, hearing is accomplished by psychological mechanisms that evolved under natural selection. But it does not follow that the things we hear are any less real. Rather, the reality of the things around us helps to explain why we have the faculty to detect them. The evolved can put us in touch with the objective.

In fact, we are all intimately familiar with entities which are such that to recognize them is to be moved by them. We call them reasons, where a reason is just a consideration that weighs in favor of an action or belief. As separate lines of research by psychologist Daniel Wegner and psychiatrist George Ainslie (as synthesized and interpreted by Daniel Dennett) strongly suggest, our reasons aren't all "in the head," and we cannot help but heed their call.

At some point in our evolution, the behavioral repertoire of our ancestors became complex enough to involve the review and evaluation of numerous possible courses of action and the formation of intentions on the basis of their projected outcomes. In a word, we got options. However, as an ultrasocial species, for whom survival and reproduction depended on close coordination of behaviors over time, we needed to manage these options in a way that could be communicated to our neighbors. That supervisor and communicator of our mental economy is the self, the more-or-less stable "I" that persists through time and feels like it is the author of action. After all, if you want to be able to make reliable threats or credible promises, you need to keep track of who you are, were, and will be. According to this perspective, reasons are a human organism's way of taking responsibility for some of the happenings in its body and environment. As such, they are inherently public and shareable. Reasons are biological adaptations, every bit as real as our hands, eyes, and ears.

I do not expect (and we do not need) a "science of good and evil." However, scientific evidence can show how it is that things matter objectively. I cannot doubt the power of reasons without presupposing the power of reasons (for doubting). That cannot be said for the power of the Holy Spirit.

Russians arrived on the western shores of North America after crossing their Eastern Ocean in 1741. After an initial period of exploration, they settled down for a full century until relinquishing their colonies to the United States. From 1799 to 1867, the colonies were governed by the Russian-American Company, a for-profit monopoly chartered under the deathbed instructions of Catherine the Great.

The Russian-American period has been treated unkindly by historians from both sides. Soviet-era accounts, though acknowledging the skill and courage of Russian adventurers, saw this Tsarist experiment at building a capitalist, American society as fundamentally flawed, casting the native Aleuts as exploited serfs. American accounts, glossing over our own subsequent exploitation of Alaska's indigenous population and natural resources, sought to emphasize that we liberated Alaska from Russian overseers who were worse, and would never be coming back.

Careful study of primary sources has convinced me that these interpretations are not supported by the facts. The Aleutian archipelago was a spectacularly rich environment with an unusually dense, thriving population whose physical and cultural well-being was devastated by contact with European invaders. But, as permanent colonists, the Russians were not so bad. The results were closer to the settlement of Greenland by Denmark than to our own settlement of the American West.

Although during the initial decades leading up to the consolidation of the Russian-American Company there was sporadic conflict (frequently disastrous to the poorly-armed and vastly-outnumbered Russians) with the native population, the colonies soon entered a relatively stable state based on cooperation, intermarriage, and official policies that provided social status, education, and professional training to children of mixed Aleut-Russian birth. Within a generation or two the day-to-day administration of the Russian-American colonies was largely in the hands of native-born Alaskans. As exemplified by the Russian adoption and adaptation of the Aleut kayak, or baidarka, many indigenous traditions and technologies (including sea otter hunting techniques, and the working of native copper deposits) were adopted by the new arrivals, reversing the usual trend in colonization, when indigenous technologies are replaced.

The Russians instituted public education, preservation of the Aleut language through transliteration of religious and other texts into Aleut via an adaptation of the Cyrillic alphabet, vaccination of the native population against smallpox, and science-based sea mammal conservation policies that were far ahead of their time. There were no such things as "reservations" for the native population in Russian America, and we owe as much to the Russians as to the Alaska Native Claims Settlement Act of 1971 that this remains true today.

The lack of support for the colonies by the home government (St. Petersburg was half a world away, and Empress Catherine's instructions a fading memory) eventually forced the sale to the United States, but also necessitated the resourcefulness and local autonomy that made the venture a success.

Russian America was a social and technological experiment that worked, until political compromises brought the experiment to a halt.

When I started Seed, I had a fairly strong aversion to technology. Somehow, sometime, science and technology had become science-and-technology. Two worlds, dissimilar in many respects, likely linked in speech for the practical goal of raising funding and attention for basic research by showing the direct, immediate correlation with usable things. I felt then that the 'and' made science more perfunctory and less romantic. And that this was a bad thing on multiple counts.

In the last year, I've come to see the relationship between science and technology very differently. We have reached the point in physics and cosmology, neuroscience, and genetics at least where technology is quintessential to advancement. Technology is not merely making the practice of science faster, less mundane or, as with microscopes, helping us see the otherwise unseeable; it is a distinct yet complementary landscape from which we can advance our knowledge of the natural world.

A physicist at CERN said to me recently that they likely wouldn't have built a new $8 billion collider if there was a better way of moving the field forward. The Blue Brain Project is using supercomputers to construct a mind because the neuroscientists involved believe it is the best way of attaining an overall understanding of the brain. Robots, I now appreciate, are not simply novelty items or tools of automation, but can be a way of gaining unique insight into humans. From simulation to supercomputing, technology is now (or at least I now see) one of science's very best friends (I could say the same for the arts). And the design, magnitude, and complexity of these technological feats satisfy my (and our) need for romance in our pursuit of truth.

The sum total of all information produced in 2008 will likely exceed the amount of information generated by humans over the past 40,000 years. Science is getting literally bigger, but as these and other major experiments churn out pentabytes of data, how do we ensure that we are actually learning more? Visualization, and more generally a strong relationship between science and design, will be essential to deriving knowledge from all this information.

In the past few years, I have been thinking and writing about "attention", and specifically, "continuous partial attention". The impetus came from my years of working at Apple, and then, Microsoft, where I thought a lot about user interface as well as our relationship to the tools we create.

I believe that attention is the most powerful tool of the human spirit and that we can enhance or augment our attention with practices like meditation and exercise, diffuse it with technologies like email and Blackberries, or alter it with pharmaceuticals. 

But lately I have observed that the way in which many of us interact with our personal technologies makes it impossible to use this extraordinary tool of attention to our advantage.

In observing others — in their offices, their homes, at cafes — the vast majority of people hold their breath especially when they first begin responding to email. On cell phones, especially when talking and walking, people tend to hyper-ventilate or over-breathe. Either of these breathing patterns disturbs oxygen and CO2 balance.

Research conducted by two NIH scientists, Margaret Chesney and David Anderson, demonstrates that breath holding can contribute significantly to stress-related diseases. The body becomes acidic, the kidneys begin to re-absorb sodium, and as the oxygen and CO2 balance is undermined, our biochemistry is thrown off.

Around this same time, I became very interested in the vagus nerve and the role it played.  The vagus nerve is one of the major cranial nerves, and wanders from the head, to the neck, chest and abdomen.  It's primary job is to mediate the autonomic nervous system, which includes the sympathetic — "fight or flight," and parasympathetic — "rest and digest" nervous systems.   

The parasympathetic nervous system governs our sense of hunger and satiety, flow of saliva and digestive enzymes, the relaxation response, and many aspects of healthy organ function.  Focusing on diaphragmatic breathing enables us to down regulate the sympathetic nervous system, which then causes the parasympathetic nervous system to become dominant.  Shallow breathing, breath holding and hyper-ventilating triggers the sympathetic nervous system, in a "fight or flight" response.

The activated sympathetic nervous system causes the liver to dump glucose and cholesterol into our blood, our heart rate increases, we don't have a sense of satiety, and our bodies anticipate and resource for the physical activity that, historically, accompanied a physical fight or flight response.  Meanwhile, when the only physical activity is sitting and  responding to email, we're sort of "all dressed up with nowhere to go."    

Some breathing patterns favor our body's move toward parasympathetic functions and other breathing  patterns favor a sympathetic nervous system response.  Buteyko (breathing techniques developed by a Russian M.D.), Andy Weil's breathing exercises, diaphragmatic breathing, certain yoga breathing techniques, all have the potential to soothe us, and to help our bodies differentiate when fight or flight is really necessary and when we can rest and digest. 

I've changed my mind about how much attention to pay to my breathing patterns and how important it is to remember to breathe when I'm using a computer, PDA or cell phone. 

I've discovered that the more consistently I tune in to healthy breathing patterns, the clearer it is to me when I'm hungry or not, the more easily I fall asleep and rest peacefully at night, and the more my outlook is consistently positive. 

I've come to believe that, within the next 5-7 years, breathing exercises will be a significant part of any fitness regime.

Imagine me, if you will, in the Oxford of 1970; a new undergraduate, thrilled by the intellectual atmosphere, the hippy clothes, joss-stick filled rooms, late nights, early morning lectures, and mind-opening cannabis. 

I joined the Society for Psychical Research and became fascinated with occultism, mediumship and the paranormal — ideas that clashed tantalisingly with the physiology and psychology I was studying. Then late one night something very strange happened. I was sitting around with friends, smoking, listening to music, and enjoying the vivid imagery of rushing down a dark tunnel towards a bright light, when my friend spoke. I couldn't reply.

"Where are you Sue?" he asked, and suddenly I seemed to be on the ceiling looking down.

"Astral projection!" I thought and then I (or some imagined flying "I") set off across Oxford, over the country, and way beyond. For more than two hours I fell through strange scenes and mystical states, losing space and time, and ultimately my self. It was an extraordinary and life-changing experience. Everything seemed brighter, more real, and more meaningful than anything in ordinary life, and I longed to understand it.

But I jumped to all the wrong conclusions. Perhaps understandably, I assumed that my spirit had left my body and that this proved all manner of things — life after death, telepathy, clairvoyance, and much, much more. I decided, with splendid, youthful over-confidence, to become a parapsychologist and prove all my closed-minded science lecturers wrong. I found a PhD place, funded myself by teaching, and began to test my memory theory of ESP. And this is where my change of mind — and heart, and everything else — came about.

I did the experiments. I tested telepathy, precognition, and clairvoyance; I got only chance results. I trained fellow students in imagery techniques and tested them again; chance results. I tested twins in pairs; chance results. I worked in play groups and nursery schools with very young children (their naturally telepathic minds are not yet warped by education, you see); chance results. I trained as a Tarot reader and tested the readings; chance results.

Occasionally I got a significant result. Oh the excitement! I responded as I think any scientist should, by checking for errors, recalculating the statistics, and repeating the experiments. But every time I either found the error responsible, or failed to repeat the results. When my enthusiasm waned, or I began to doubt my original beliefs, there was always another corner to turn — always someone saying "But you must try xxx". It was probably three or four years before I ran out of xxxs.

I remember the very moment when something snapped (or should I say "I seem to …" in case it's a false flash-bulb memory). I was lying in the bath trying to fit my latest null results into paranormal theory, when it occurred to me for the very first time that I might have been completely wrong, and my tutors right. Perhaps there were no paranormal phenomena at all.

As far as I can remember, this scary thought took some time to sink in. I did more experiments, and got more chance results. Parapsychologists called me a "psi-inhibitory experimenter", meaning that I didn't get paranormal results because I didn't believe strongly enough. I studied other people's results and found more errors and even outright fraud. By the time my PhD was completed, I had become a sceptic.

Until then, my whole identity had been bound up with the paranormal. I had shunned a sensible PhD place, and ruined my chances of a career in academia (as my tutor at Oxford liked to say). I had hunted ghosts and poltergeists, trained as a witch, attended spiritualist churches, and stared into crystal balls. But all of that had to go.

Once the decision was made it was actually quite easy. Like many big changes in life this one was terrifying in prospect but easy in retrospect. I soon became "rentasceptic", appearing on TV shows to explain how the illusions work, why there is no telepathy, and how to explain near-death experiences by events in the brain.

What remains now is a kind of openness to evidence. However firmly I believe in some theory (on consciousness, memes or whatever); however closely I might be identified with some position or claim, I know that the world won't fall apart if I have to change my mind.

I am a heretic. I have come to question the key assumption behind this survey: "When facts change your mind, that's science." This idea that science is an objective fact-driven pursuit is laudable, seductive and - alas - a mirage.

Science is a never-ending dialogue between theorists and experimenters. But people are central to that dialogue. And people ignore facts. They distort them or select the ones that suit their cause, depending on how they interpret their meaning. Or they don't ask the right questions to obtain the relevant facts.

Contrary to the myth of the ugly fact that can topple a beautiful theory - and against the grain of our lofty expectations - scientists sometimes play fast and loose with data, highlighting what that suits them and ignoring stuff that doesn't.

The harsh spotlight of the media often encourages them to strike a confident pose even if the facts don't. I am often struck by how facts are ignored, insufficient or even abused. I back well-designed animal research but am puzzled by how scientists chose to ignore the basic fact that vivisection is so inefficient at generating cures for human disease. Intelligent design is for cretins but, despite the endless proselytizing about the success of Darwin - assuming that evolution is a fact - I could still see it being superseded, rather as Einstein's ideas replaced Newton's law of gravity. I believe in man-made global warming but computer-projected facts that purportedly say what is in store for the Earth in the next century leave me cold.

I support embryo research but was irritated by one oft-cited fact in the recent British debate on the manufacture of animal-human hybrid embryos: "only a tiny fraction" of the hybrid made by the Dolly cloning method (nuclear transfer) contains animal DNA. Given that it features in mitochondria, which are central to a range of diseases; given a single spelling mistake in DNA can be catastrophic; and given no-one really understands what nuclear transfer does, this "fact" was propaganda.

Some of the most exotic and prestigious parts of modern science are unfettered by facts. I have recently written about whether our very ability to study the heavens may have shortened the inferred lifetime of the cosmos, whether there are two dimensions of time, even the prospect that time itself could cease to be in billions of years. The field of cosmology is in desperate need of more facts, as highlighted by the aphorisms made at its expense ("There is speculation, pure speculation and cosmology.... cosmologists are often in error, never in doubt')

Scientists have to make judgements about the merits of new facts. Ignoring them in the light of strong intuition is the mark of a great scientist. Take Einstein, for example: when Kaufmann claimed to have experimental facts that refuted special relativity, he stuck to his guns and was proved right. Equally, Einstein's intuition misled him in his last three decades, when he pursued a fruitless quest for a unified field theory that was not helped by his lack of interest in novel facts - the new theoretical ideas, particles and interactions that had emerged at this time.

When it comes to work in progress, in particular, many scientists treat science like a religion - the facts should be made to fit the creed. However, facts are necessary for science but not sufficient. Science is when, in the face of extreme scepticism, enough facts accrue to change lots of minds.

Our rising and now excessive faith in facts alone can be seen in a change in the translation of the motto of the world's oldest academy of science, the Royal Society. Nullius in Verba was once taken as 'on the word of no one' to highlight the extraordinary power that empirical evidence bestowed upon science. The message was that experimental evidence trumped personal authority.

Today the Society talks of the need to 'verify all statements by an appeal to facts determined by experiment'. But whose facts? Was it a well-designed experiment? And are we getting all the relevant facts? The Society should adopt the snappier version that captures its original spirit: 'Take nobody's word for it'.

Edge’s question this year wittily refers to a way of demarcating science from philosophy and religion.  “When thinking changes your mind, that’s philosophy . . . .  When facts change your mind, that’s science.” Behind the witticism lies the important claim that science—or more precisely, scientific theories—can be clearly distinguished from all other theories, that scientific theories bear a special mark, and what this mark is is falsifiability. Said Popper:  The criterion of the scientific status of a theory is its falsifiability.  

For most scientists, this is all they need to know about the philosophy of science. It was bracing to come upon such a clear and precise criterion for identifying  scientific theories. And it was gratifying to see how Popper used it to discredit the claims that  psychoanalysis and Marxism are scientific theories. It had long seemed to me that the falsifiability test was basically right and enormously useful.

But then I started to read Popper’s work carefully, to teach him in my philosophy of science classes, and to look to scientific practice to see whether his theory survives the test of falsifiability (at least as a description of how successful science gets done). And I’ve changed my mind.

For one thing, Popper’s characterization of how science is practiced—as a cycle of conjecture and refutation—bears little relation to what goes on in the labs and journals. He describes science as if it was skeet-shooting, as if the only goal of science is to prove that one theory after another is false. But just open a copy of Science.  To pick a random example: “In a probabilistic learning task, A1-allele carriers with reduced dopamine D2 receptor densities learned to avoid actions with negative consequences less efficiently.” Not, “We tried to falsify the hypothesis that A1 carriers are less efficient learners, and failed.” Scientists rarely write the way that Popper says they should, and a good Popperian should recognize that the Master may have over-simplified the logic of theory testing.

Also, scientists don’t, and shouldn’t, jettison a theory as soon as a disconfirming datum comes in. As Francis Crick once said, “Any theory that can account for all of the facts is wrong, because some of the facts are always wrong.” Scientists rightly question a datum that appears to falsify an elegant and well-supported theory, and they rightly add assumptions and qualifications and complications to a theory as they learn more about the world. As Imre Lakatos, a less-cited (but more subtle) philosopher of science points out, all scientific theories are unfalsifiable. The ones we take seriously are those that lead to “progressive” research programs, where a small change accommodates a large swath of past and future data. And the ones we abandon are those that lead to “degenerate” ones, where the theory gets patched and re-patched at the same rate as new facts come in.

Another problem with the falsifiability criterion is that I have seen it  become a blunt instrument, unthinkingly applied. Popper tried to use it to discredit not only Marxism and Freudianism as scientific theories but also Darwin’s theory of natural selection—a position that only a creationist could hold today. I have seen scientists claim that major theories in contemporary cosmology and physics are not “science” because they can’t think of a simple test that would falsify them. You’d think that when they are faced with a conflict between what scientists really do and their memorized Popperian sound-bite about how science ought to be done, they might question the sound bite, and go back and learn more than a single sentence from the philosophy of science. But such is the godlike authority of Popper that his is the one theory that can never be falsified!

Finally, I’ve come to think that identifying scientificality with falsifiability lets certain non-scientific theories off the hook, by saying that we should try to find good reasons to believe whether a theory is true or false only when that theory is called “science.” It allows believers to protect their pet theories by saying that they can’t be, and shouldn’t be, subject to falsification, just because they’re clearly not scientific theories. Take the theory that there’s an omnipotent, omniscient, beneficent God. It may not be a scientific hypothesis, but it seems to me to be eminently falsifiable; in fact, it seems to have been amply falsified.   But because falsifiability is seen as demarcating the scientific, and since theism is so clearly not scientific, believers in religious ideologies get a free pass. The same is true for many political ideologies. The parity between scientific and nonscientific ideas is concealed by thinking that there’s a simple test that distinguishes science from nonscience, and that that test is falsifiability.

I work in a borderland between social science and medicine, and I therefore often find myself trying to reconcile conflicting facts and perspectives about human biology and behavior.  There are fellow travelers at this border, of course, heading in both directions, or just dawdling, but the border is both sparsely populated and chaotic.  The border is also, strangely, well patrolled, and it is often quite hard to get authorities on both sides to coordinate activities.  Once in a while, however, I find that my passport (never quite in order, according to officials) has acquired a new visa.  For me, this past year, I acquired the conviction that human evolution may proceed much faster than I had thought, and that humans themselves may be responsible. 

In short, I have changed my mind about how people come literally to embody the social world around them.  I once thought that we internalized cultural factors by forming memories, acquiring language, or bearing emotional and physical marks (of poverty, of conquest).  I thought that this was the limit of the ways in which our bodies were shaped by our social environment.  In particular, I thought that our genes were historically immutable, and that it was not possible to imagine a conversation between culture and genetics.  I thought that we as a species evolved over time frames far too long to be influenced by human actions. 

I now think this is wrong, and that the alternative — that we are evolving in real time, under the pressure of discernable social and historical forces — is true.  Rather than a monologue of genetics, or a soliloquy of culture, there is a dialectic between genetics and culture.

Evidence has been mounting for a decade. The best example so far is the evolution of lactose tolerance in adults.  The ability of adults to digest lactose (a sugar in milk) confers evolutionary advantages only when a stable supply of milk is available, such as after milk-producing animals (sheep, cattle, goats) have been domesticated.  The advantages are several, ranging from a source of valuable calories to a source of necessary hydration during times of water shortage or spoilage.  Amazingly, just over the last 3-9 thousand years, there have been several adaptive mutations in widely separated populations in Africa and Europe, all conferring the ability to digest lactose (as shown by Sarah Tishkoff and others).  These mutations are principally seen in populations who are herders, and not in nearby populations who have retained a hunter/gatherer lifestyle. This trait is sufficiently advantageous that those with the trait have notably many more descendants than those without.

A similar story can be told about mutations that have arisen in the relatively recent historical past that confer advantages in terms of surviving epidemic diseases such as typhoid.  Since these diseases were made more likely when the density of human settlements increased and far-flung trade became possible, here we have another example of how culture may affect our genes.

But this past year, a paper by John Hawks and colleagues in PNASfunctioned like the staccato plunk of a customs agent stamping my documents and waving me on.  The paper showed that the human genome may be changing at an accelerating rate over the past 80,000 years, and that this change may be in response not only to population growth and adaptation to new environments, but also to cultural developments that have made it possible for humans to sustain such population growth or survive in such environments.

Our biology and our culture have always been in conversation of course — just not (I had thought) on the genetic level.  For example, rising socio-economic status with industrial development results in people becoming taller (a biological effect of a cultural development) and taller people require architecture to change (a cultural effect of a biological development).  Anyone marveling at the small size of beds in colonial-era houses knows this firsthand.  Similarly, an epidemic may induce large-scale social changes, modifying kinship systems or political power.  But genetic change over short time periods?  Yes.

Why does this matter?  Because it is hard to know where this would stop.  There may be genetic variants that favor survival in cities, that favor saving for retirement, that favor consumption of alcohol, or that favor a preference for complicated social networks.  There may be genetic variants (based on altruistic genes that are a part of our hominid heritage) that favor living in a democratic society, others that favor living among computers, still others that favor certain kinds of visual perception (maybe we are all more myopic as a result of Medieval lens grinders).  Modern cultural forms may favor some traits over others.  Maybe even the more complex world we live in nowadays really is making us smarter. 

This has been very difficult for me to accept because, unfortunately, this also means that it may be the case that particular ways of living create advantages for some, but not all, members of our species.  Certain groups may acquire (admittedly, over centuries) certain advantages, and there might be positive or negative feedback loops between genetics and culture.  Maybe some of us really are better able to cope with modernity than others.  The idea that what we choose to do with our world modifies what kind of offspring we have is as amazing as it is troubling.

I was on a train back from the seaside. The summer was gone and the philosophy teacher (at that time I was attending the high-school) had assigned us a book to read.  The title sounded like "The Birth of modern Science in Europe". I started to leaf through it, without expecting anything special.

Until then, I had a purist vision of science: I supposed that the development of science was - in some way - a deterministic process, scientists proceeded in a linear way doing their experiments, theories arose in the science community under a common agreement.

Well..  my vision of science was dramatically different from that one I experienced some years later! With surprise and astonishment, I discovered that Sir Isaac Newton had a not-hidden passion for Alchemy - probably the furthest thing from science I could imagine - Nicolaus Copernicus wrote to the Pope begging to accept his theories, Galileo and other scientists fought not only against the Roman Church and Aristotle's thought but maybe more often one against the others just to prevail.

In two weeks I finished the book and then my way of thinking changed. I understood that science was not only a pursuit of knowledge but a social process too, with its rules and tricks: a never-ending tale such as human life. I have never forgotten it and since then, my curiosity and passion for science have been rising more and more. Definitely, that book has changed my mind.

As a young graduate student in operations research I was avid believer in the power of scientific modelling. How wrong I was. Often, modelling is searching for a coin under the light of science, and not where it is.

First, all models have certain degree of approximation. Second, at least in operations research, human factors,errors, randomness, unexpected developments, social behaviors, human errors all are influencing the results, or are not accounted for in the modelling. In time I become more skeptical and doubtful.

It helps if you can maintain your sense of humor. In the end, it is not about the data or the changes in the data, but how you see it, and how much you believe in it.

Back in 1968, when I first heard about global warming while visiting the Scripps Institute of Oceanography, almost everyone thought that serious problems were several centuries in the future. That's because no one realized how ravenous the world's appetite for coal and oil would become during a mere 40 years. They also thought that problems would develop slowly. Wrong again.
I tuned into abrupt climate change about 1984, when the Greenland ice cores showed big jumps in temperature and snowfall, stepping up and down in a mere decade but lasting centuries. I worried about global warming setting off another flip but I still didn't revise my notions about a slow time scale for the present greenhouse warming.

Greenland changed my mind. About 2004, the speedup of the Greenland glaciers made a lot of climate scientists revise their notions about how fast things were changing. When the summer earthquakes associated with glacial movement doubled and then redoubled in a mere ten years, it made me feel as if I was standing on shaky ground, that bigger things could happen at any time.
Then I saw the data on major floods and fires, steep increases every decade since 1950 and on all continents. That's not trouble moving around. It is called global climate change. It may not be abrupt but it's been fast.

For drought, which had been averaging about 15 percent of the world's land surface at any one time, there was a step up to a new baseline of 25 percent which occurred with the 1982 El Niño. That's not gradual change but an abrupt shift to a new global climate.

But the most sobering realization came when I was going through the Amazon drought data on the big El Niños in 1972, 1982, and 1997. Ten years ago, we nearly lost two of the world's three major tropical rain forests to fires. If that mega Nino had lasted two years instead of one, we could have seen the atmosphere's excess CO2 rise 40 percent over a few years — and likely an even bigger increase in our climate troubles. Furthermore, missing all of those green leaves to remove CO2 from the air, the annual bump up of CO2 concentration would have become half again as large. That's like the movie shifting into fast forward.

And we're not even back paddling as fast as we can, just drifting toward the falls. If I were a student or young professional, seeking my future being trashed, I'd be mad as hell. And hell is a pretty good metaphor for where we are heading if we don't get our act together. Quickly.

I've changed my mind about countless matters, but most if not all such changes have been vaguely akin to switching from brand A to brand B. In some deep sense, however, I feel that I've never really changed how I think about or evaluate things. This may sound like a severe case of cerebral stenosis, but I think the condition is universal. Although people change their minds, they do so in an invariant, convergent sort of way, and I find this to be of more interest than the brand switches, important as they sometimes are.

I take heart that this stance can be viewed as something other than stubborn rigidity from the so-called Agreement Theorem of Nobel Prize-winning game-theorist Robert Aumann. His theorem can be roughly paraphrased as follows: Two individuals cannot forever agree to disagree.

An important definition allows for a slightly fuller statement. Information is termed "common knowledge" among a group of people if all parties know it, know that the others know it, know that the others know they know it, and so on. It is much more than "mutual knowledge," which requires only that the parties know the particular bit of information, not that they be aware of the others' knowledge.

Aumann showed that as agents' beliefs, formed in rational response to different bits of private information, gradually become common knowledge, their beliefs change and eventually coincide.

Thus in whatever rational ways each of us comes to change his or her mind, in the long run the rest of us will follow suit. Of course, as Keynes observed, in the long run, we're all dead.

Another problem is Aumann's result doesn't say anything about the convergence of irrational agents.

Aside from whether Apple matters (whoops!), the biggest thing I've changed my mind about is climate change. There was no one thing that convinced me to flip from wait-and-see to the-time-for-debate-is-over. Instead, there were three things, which combined for me in early 2006. There was, of course, the scientific evidence, which kept getting more persuasive. There was also economics, and the recognition that moving to alternative, sustainable energy was going to be cheaper over the long run as oil got more expensive. And finally there was geopolitics, with ample evidence of how top-down oil riches destabilized a region and then the world. No one reason was enough to win me over to total energy regime change, but together they seemed win-win-win.

Now I see the entire energy and environmental picture through a carbon lens. It's very clarifying. Put CO2 above everything else, and suddenly you can make reasonable economic calculations about risks and benefits, without getting caught up in the knotty politics of full-spectrum environmentalism. I was a climate skeptic and now I'm a carbon zealot. I seem to annoy traditional environmentalists just as much, but I like to think that I've moved from behind to in front.

Here's a happy example of me being wrong. Other researchers interested in Virtual Reality had been proposing as early as twenty years ago that VR would someday be useful for the treatment of psychological disorders such as post-traumatic stress disorder.

I did not agree. In fact, I had strong arguments as to why this ought not to work. There was evidence that the brain created distinct "homuncular personas" for virtual world experiences, and reasons to believe that these personas were tied to increasingly distinct bundles of emotional patterns. Therefore, emotional patterns attached to real world situations would, I
surmised, remain attached to those situations. The earliest research on PTSD treatment in VR seemed awfully shaky to me, and I was not very encouraging to younger researchers who were interested in it.

The idea of using VR for PTSD treatment seemed less likely to work than various other therapeutic applications of VR, which were more centered around somatic processes. For instance, VR can be used as an enhanced physical training environment. The first example, from the 1980s, involved juggling. If virtual juggling balls fly more slowly than real balls, then they are easier to juggle. You can then gradually increase the speed, in order to provide a more gradual path for improving skills than would be available in physical reality. (This idea came about initially because it was so hard to make early VR systems go as fast as the reality they were emulating. In the old VPL Research lab, where a lot of VR tools were initially prototyped, we were motivated to be alert for potential virtues hiding within the limitations of the era.) Variations on this strategy have become well established. For instance, patients are learning to use prosthetic limbs more quickly by using VR these days.

Beyond rational argument, I was biased in other ways: The therapeutic use of VR seemed "too cute," and sounded too much like a press release in waiting.

Well, I was wrong. PTSD treatment in VR is now a well-established field with its own conferences, journals publishing well-repeated results, and clinical practitioners. Sadly, the Iraq war has provided all too many patients, and has also motivated increased funding for research in this subfield of VR applications.

One of the reasons I was wrong is that I didn't see that the same tactic we used on juggling balls (of gradually adapting the content and design of a virtual world to the instantaneous state of the user/inhabitant) could be applied in a less somatic way. For instance, in some clinical protocols, a traumatic event is represented in VR with gradually changing levels of realism as part of the course of treatment.

Maybe I was locked into seeing VR through the filters of the limitations of its earliest years. Maybe I was too concerned about the cuteness factor. At any rate, I'm glad there was a diversity of mindsets in the research community so that others could see where I didn't.

I'm concerned that diversity of thought in some of the microclimates of the scientific community is narrowing these days instead of broadening. I blame the nature of certain online tools. Tools like the Wikipedia encourage the false worldview that we already know enough to agree on a single account of reality, and anonymous blog comment rolls can bring out mob-like behaviors in young scientists who use them.

At any rate, one of the consolations of science is that being wrong on
occasion lets you know you don't know everything and motivates renewed
curiosity. Being aware of being wrong once in a while keeps you young.

I was an earnest student in Catechism class. The climax of our early training, as thirteen year-olds, was an intense retreat in preparation for the sacrament of Confirmation. Even now I vividly remember the rapture of belief, the glow everyday events acquired when I felt that they reflected a grand scheme of the universe, in which I had a personal place. Soon afterward, though, came disillusionment. As I learned more about science, some of the concepts and explanations in the ancient sacred texts came to seem clearly wrong; and as I learned more about history and how it is recorded, some of the stories in those texts came to seem very doubtful.

What I found most disillusioning, however, was not that the sacred texts contained errors, but that they suffered by comparison. Compared to what I was learning in science, they offered few truly surprising and powerful insights. Where was there a vision to rival the concepts of infinite space, of vast expanses of time, of distant stars that rivaled and surpassed our Sun? Or of hidden forces and new, invisible forms of "light"? Or of tremendous energies that humans could, by understanding natural processes, learn to liberate and control? I came to think that if God exists, He (or She, or They, or It ) did a much more impressive job revealing Himself in the world than in the old books; and that the power of faith and prayer is elusive and unreliable, compared to the everyday miracles of medicine and technology.

For many years, like some of my colleagues and some recent bestselling authors, I thought that active, aggressive debunking might be in order. I've changed my mind. One factor was my study of intellectual history. Many of my greatest heros in physics, including Galileo, Newton, Faraday, Maxwell, and Planck, were deeply religious people. They truly believed that what they were doing, in their scientific studies, was discovering the mind of God. Many of Bach's and Mozart's most awesome productions are religiously inspired. Saint Augustine's writings display one of the most impressive intellects ever. And so on. Can you imagine hectoring this group? And what would be the point? Did their religious beliefs make them stupid, or stifle their creativity?

Also, debunking hasn't worked very well. David Hume already set out the main arguments for religious skepticism in the early eighteenth century. Bertrand Russell and many others have augmented them since. Textual criticism reduces fundamentalism to absurdity. Modern molecular biology, rooted in physics and chemistry, demonstrates that life is a natural process; Darwinian evolution illuminates its natural origin. These insights have been highly publicized for many decades, yet religious doctrines that contradict some or all of them have not merely survived, but prospered.

Why? Part of the answer is social. People tend to stay with the religion of their birth, for the same sorts of reasons that they stay loyal to their clan, or their country.

But beyond that, religion addresses some deep concerns that science does not yet, for most people, touch. The human yearning for meaningful understanding, our fear of death — these deep motivations are not going to vanish. 

Understanding, of course, is what science is all about. Many people imagine, however, that scientific understanding is dry and mundane, with no scope for wonder and amazement. That is simply ignorant. Looking for wonder and amazement? Try some quantum theory!

Beyond understanding inter-connected facts, people want to discover their significance or meaning. Neuroscientists are beginning to map human motivations and drives at the molecular level. As this work advances, we will attain a deeper understanding of the meaning of meaning. Freud's theories had enormous impact, not because they are correct, but because they "explained" why people feel and act as they do. Correct and powerful theories that address these issues are sure to have much greater impact.

Meanwhile, medical science is taking a deep look at aging. Within the next century, it may be possible for people to prolong youth and good health for many years — perhaps indefinitely. This would, of course, profoundly change our relationship with death. So to me the important challenge is not to debunk religion, but to address its issues in better ways.

I used to take for granted an assumption that the universe is infinite. There are innumerable little things about which I've changed my mind but the size of the universe is literally the biggest physical attribute that has inspired a radical change in my thinking. I won't claim I "believe" the universe is finite, just that I recognize that a finite universe is a realistic possibility for our cosmos.

The general theory of relativity describes local curves in spacetime due to matter and energy. This model of gravity as a warped spacetime has seen countless successes beginning with a confirmation of an anomaly in the orbit of mercury and continuing with the predictions of the existence of black holes, the expansion of spacetime, and the creation of the universe in a big bang. However, general relativity says very little about the global shape and size of the universe. Two spaces can have the same curvature locally but very different global properties. A flat space, for instance, can be infinite but there is another possibility, that it is finite and edgeless, wrapped back onto itself like a doughnut — but still flat. And there are an infinite number of ways of folding spacetime into finite, edgeless shapes, a kind of cosmic origami.

I grew up believing the universe was infinite. It was never taught to me in the sense that no one ever tried to prove to me the universe was infinite. It just seemed a natural assumption based on simplicity. That sense of simplicity no longer resonates as true once we have confronted that there must be a theory of gravity beyond General Relativity that involves the quantization, the discretization, of spacetime itself. In cosmology we have become accustomed to models of the universe that invoke extra dimensions, all of which are finite and it seems fair to imagine a universe born with all of its dimensions finite and compact. Then we are left with the mystery of why only three dimensions become so incredibly huge while the others remain curled up and small. We even hope to test models of extra dimensions in imminent laboratory experiments. These ideas are not remote and fantastical. They are testable.

People have said to me they were very surprised (disappointed) that I suggested the universe was finite. The infinite universe, they believed, was full of infinite potential and so philosophically (emotionally) so much richer and more thrilling. I explained that my suggestion of a finite universe was not a moral failing on my part, nor a consequence of diminished imagination. More thrilling was the knowledge that it does not matter what I believe. It does not matter if I prefer an infinite universe or a finite universe. Nature is not designed to satisfy our personal longings. Nature is what she is and it's a privilege merely to be privy to her mathematical codes.

I don't know that the universe is finite and so I don't believe that it is finite. I don't know that the universe is infinite and so I don't believe that it is infinite. I do see, however, that our mathematical reasoning has led to remarkable and sometimes psychologically uncomfortable discoveries. And I do believe that it is a realistic possibility that one day we may discover the shape of the entire universe. If the universe is too vast for us to ever observe the extent of space, we may still discover the size and shape of internal dimensions. From small extra dimensions we might possibly infer the size and shape of the large dimensions. Until then, I won't make up my mind.

I've changed my mind about the use of enhancement drugs by healthy people. A year ago, if asked, I'd have been against the idea, whereas now I think there's much to be said for it.

The ultimate test of such a change of mind is how I'd feel if my offspring (both adults) went down that road, and my answer is that with tolerable risks of side effects and zero risk of addiction, then I'd feel OK if there was an appropriate purpose to it. 'Appropriate purposes' exclude gaining an unfair advantage or unwillingly following the demands of others, but include gaining a better return on an investment of study or of developing a skill.

I became interested in the issues surrounding cognitive enhancement as one example of debates about human enhancement — debates that can only get more vigorous in future. It's also an example of a topic in which both natural and social sciences can contribute to better regulation — another theme that interests me. Thinking about the issues and looking at the evidence-based literatures made me realise how shallow was my own instinctive aversion to the use of such drugs by healthy people. It also led to a thoughtful article by Barbara Sahakian and Sharon Morein-Zamir in Nature (20 December 2007) that triggered many blog discussions.

Social scientists report that a small but significant proportion of students on at least some campuses are using prescription drugs in order to help their studies — drugs such as modafinil (prescribed for narcolepsy) and methylphenidate (prescribed for attention-deficit hyperactivity disorder). I've not seen studies that quantify similar use by academic faculty, or by people in other non-military walks of life, though there is no doubt that it is happening. There are anecdotal accounts and experimental small-scale trials showing that such drugs do indeed improve performance to a modest degree under particular circumstances.

New cognitive enhancing drugs are being developed, officially for therapy. And the therapeutic importance — both current and potential — of such drugs is indeed significant. But manufacturers won't turn away the significant revenues from illegal use by the healthy.

That word 'illegal' is the rub. Off-prescription use is illegal in the United States, at least. But that illegality reflects an official drugs culture that is highly questionable. It's a culture in which the Food and Drugs Administration seems reluctant generally to embrace the regulation of enhancement for the healthy, though it is empowered to do so. It is also a culture that is rightly concerned about risk but wrongly founded in the idea that drugs used by healthy people are by definition a Bad Thing. That in turn reflects instinctive attitudes to do with 'naturalness' and 'cheating on yourself' that don't stand up to rational consideration. Perhaps more to the point, they don't stand up to behavioral consideration, as Viagra has shown.

Research and societal discussions are necessary before cognitive enhancement drugs should be made legally available for the healthy, but I now believe that that is the right direction in which to head.

With reference to the precursor statements of this year's annual question, there are facts behind that change of mind, some thinking, and some secular faith in humans, too.

Public discourse on very long-term planning is riddled with inconsistencies. Mostly we discount the future very heavily — investment decisions are expected to pay off within a decade or two. But when we do look further ahead — in discussions of energy policy, global warming and so forth — we underestimate the possible pace of transformational change. In particular, we need to keep our minds open — or at least ajar — to the possibility that humans themselves could change drastically within a few centuries.

Our medieval forebears in Europe had a cosmic perspective that was a million-fold more constricted than ours. Their entire cosmology — from creation to apocalypse — spanned only a few thousand years. Today, the stupendous time spans of the evolutionary past are part of common culture — except among some creationists and fundamentalists. Moreover, we are mindful of immense future potential. It seems absurd to regard humans as the culmination of the evolutionary tree. Any creatures witnessing the Sun's demise 6 billion years hence won't be human — they could be as different from us as we are from slime mould.

But, despite these hugely stretched conceptual horizons, the timescale on which we can sensibly plan, or make confident forecasts has got shorter rather than longer. Medieval people, despite their constricted cosmology, did not expect drastic changes within a human life; they devotedly added bricks to cathedrals that would take a century to finish. For us, unlike for them, the next century will surely be drastically different from the present. There is a huge disjunction between the every-shortening timescales of historical and technical change, and the near-infinite time spans over which the cosmos itself evolves.

Human-induced changes are occurring with runaway speed. It's hard to predict a mere century from now, because what will happen depends on us — this is the first century where humans can collectively transform, or even ravage, the entire biosphere. Humanity will soon itself be malleable, to an extent that's qualitatively new in the history of our species. New drugs (and perhaps even implants into our brains) could change human character; the cyberworld has potential that is both exhilarating and frightening. We can't confidently guess lifestyles, attitudes, social structures, or population sizes a century hence. Indeed, it's not even clear for how long our descendants would remain distinctively 'human'. Darwin himself noted that "not one living species will transmit its unaltered likeness to a distant futurity". Our own species will surely change and diversify faster than any predecessor —— via human-induced modifications (whether intelligently-controlled or unintended), not by natural selection alone. Just how fast this could happen is disputed by experts, but the post-human era may be only centuries away.

These thoughts might seem irrelevant to practical discussions — and best left to speculative academics and cosmologists. I used to think this. But humans are now, individually and collectively, so greatly empowered by rapidly changing technology that we can, by design, or as unintended consequences — engender global changes that resonate for centuries. And, sometimes at least, policy-makers indeed think far ahead.

The global warming induced by fossil fuels burnt in the next fifty years could trigger gradual sea level rises that continue for a millennium or more. And in assessing sites for radioactive waste disposal, governments impose the requirements that they be secure for ten thousand years.

It's real political progress that these long-term challenges are higher on the international agenda, and that planners seriously worry about what might happen more than a century hence.

But in such planning, we need to be mindful that it may not be people like us who confront the consequences of our actions today. We are custodians of a 'posthuman' future — here on Earth and perhaps beyond — that can't just be left to writers of science fiction.

In November 2002, Clay Shirky organized a "social software summit," based on the premise that we were entering a "golden age of social software... greatly extending the ability of groups to self-organize."

I was skeptical of the term "social software" at the time. The explicit social software of the day, applications like friendster and meetup, were interesting, but didn't seem likely to be the seed of the next big Silicon Valley revolution.

I preferred to focus instead on the related ideas that I eventually formulated as "Web 2.0," namely that the internet is displacing Microsoft Windows as the dominant software development platform, and that the competitive edge on that platform comes from aggregating the collective intelligence of everyone who uses the platform. The common thread that linked Google's PageRank, ebay's marketplace, Amazon's user reviews, Wikipedia's user-generated encyclopedia, and CraigsList's self-service classified advertising seemed too broad a phenomenon to be successfully captured by the term "social software." (This is also my complaint about the term "user generated content.") By framing the phenomenon too narrowly, you can exclude the exemplars that help to understand its true nature. I was looking for a bigger metaphor, one that would tie together everything from open source software to the rise of web applications.

You wouldn't think to describe Google as social software, yet Google's search results are profoundly shaped by its collective interactions with its users: every time someone makes a link on the web, Google follows that link to find the new site. It weights the value of the link based on a kind of implicit social graph (a link from site A is more authoritative than one from site B, based in part on the size and quality of the network that in turn references either A or B). When someone makes a search, they also benefit from the data Google has mined from the choices millions of other people have made when following links provided as the result of previous searches.

You wouldn't describe ebay or Craigslist or Wikipedia as social software either, yet each of them is the product of a passionate community, without which none of those sites would exist, and from which they draw their strength, like Antaeus touching mother earth. Photo sharing site Flickr or bookmark sharing site del.icio.us (both now owned by Yahoo!) also exploit the power of an internet community to build a collective work that is more valuable than could be provided by an individual contributor. But again, the social aspect is implicit — harnessed and applied, but never the featured act.

Now, five years after Clay's social software summit, Facebook, an application that explicitly explores the notion of the social network, has captured the imagination of those looking for the next internet frontier. I find myself ruefully remembering my skeptical comments to Clay after the summit, and wondering if he's saying "I told you so."

Mark Zuckerberg, Facebook's young founder and CEO, woke up the industry when he began speaking of "the social graph" — that's computer-science-speak for the mathematical structure that maps the relationships between people participating in Facebook — as the core of his platform. There is real power in thinking of today's leading internet applications explicitly as social software.

Mark's insight that the opportunity is not just about building a "social networking site" but rather building a platform based on the social graph itself provides a lens through which to re-think countless other applications. Products like xobni (inbox spelled backwards) and MarkLogic's MarkMail explore the social graph hidden in our email communications; Google and Yahoo! have both announced projects around this same idea. Google also acquired Jaiku, a pioneer in building a social-graph enabled address book for the phone.

This is not to say that the idea of the social graph as the next big thing invalidates the other insights I was working with. Instead, it clarifies and expands them:

• Massive collections of data and the software that manipulates those collections, not software alone, are the heart of the next generation of applications.
• The social graph is only one instance of a class of data structure that will prove increasingly important as we build applications powered by data at internet scale. You can think of the mapping of people, businesses, and events to places as the "location graph", or the relationship of search queries to results and advertisements as the "question-answer graph."
• The graph exists outside of any particular application; multiple applications may explore and expose parts of it, gradually building a model of relationships that exist in the real world.
• As these various data graphs become the indispensable foundation of the next generation "internet operating system," we face one of two outcomes: either the data will be shared by interoperable applications, or the company that first gets to a critical mass of useful data will become the supplier to other applications, and ultimately the master of that domain.

So have I really changed my mind? As you can see, I'm incorporating "social software" into my own ongoing explanations of the future of computer applications.

It's curious to look back at the notes from that first Social Software summit. Many core insights are there, but the details are all wrong. Many of the projects and companies mentioned have disappeared, while the ideas have moved beyond that small group of 30 or so people, and in the process have become clearer and more focused, imperceptibly shifting from what we thought then to what we think now.

Both Clay, who thought then that "social software" was a meaningful metaphor and I, who found it less useful then than I do today, have changed our minds. A concept is a frame, an organizing principle, a tool that helps us see. It seems to me that we all change our minds every day through the accretion of new facts, new ideas, new circumstances. We constantly retell the story of the past as seen through the lens of the present, and only sometimes are the changes profound enough to require a complete repudiation of what went before.

Ideas themselves are perhaps the ultimate social software, evolving via the conversations we have with each other, the artifacts we create, and the stories we tell to explain them.

Yes, if facts change our mind, that's science. But when ideas change our minds, we see those facts afresh, and that's history, culture, science, and philosophy all in one.

What have I changed my mind about? Online privacy.

For a long time, I thought that people would rise to the challenge and start effectively protecting their own privacy online, using tools and services that the market would provide. Many companies offered such services, and almost none of them succeeded (at least not with their original business plans). People simply weren't interested: They were both paranoid and careless, and took little trouble to inform themselves. (Of course, if you've ever attempted to read an online privacy statement, you'll understand why.)

But now I've simply changed my mind and realized that the whole question needs reframing - which Facebook et al. are in the process of doing. Users have never learned the power to say no to marketers who want their data...but they are getting into the habit of controlling it themselves because Facebook is teaching them that this is a natural thing to do.

Yes, Facebook certainly managed to draw attention to the whole "privacy" question with its Beacon tracking tool, but for most Facebook users the big question is how many people they can get to see their feed. They are happy to share their information with friends, and they consider it the most natural thing in the world to distinguish among friends (see new Facebook add-on applications such as Top Friends and Cliquey) and to manage their privacy settings to determine who can see which parts of their profile. So why shouldn't they do the same thing vis a vis marketers?

For example, I fly a lot, and I use various applications to let certain friends know where I am and plan to be. I'd be delighted to share that information with certain airlines and hotels if I knew they would send me special offers. (In fact, United Airlines once asked me to send in my frequent flyer statements from up to three competing airlines in exchange for 2000 bonus miles each. I gladly did so, and would have done it for free. I *want* United to know what a good customer I am...and how much more of my business they could win if they offered me even better deals.)

In short, for many users the Web is becoming a mirror, with users in control, rather than a heavily surveilled stage. The question isn't how to protect users' privacy, but rather how to give them better tools to control their own data - not by selling privacy or by getting them to "sell" their data, , but by feeding their natural fascination with themselves and allowing them to manage their own presence. What once seemed like an onerous, weird task becomes akin to self-grooming online.

This begs a lot of questions, I know, including real, coercive invasions of privacy by government agencies, but I think the in-control users of the future will be better equipped to fight back. Give them a little time and a few bad experiences, and they'll start to make the distinction between an airline selling seats and a government that simply won't allow you to take it off your buddy list.

In 1975, as a newly minted PhD who had just published my first paper on group selection, I was invited by Science magazine to review a book by Michael Gilpin titled Group Selection in Predator Prey Communities. Gilpin was one of the first biologists to appreciate the importance of what Stuart Kauffman would call "the sciences of complexity." In his book, he was claiming that complex interactions could make group selection a more important evolutionary force than the vast majority of biologists had concluded on the basis of more simple mathematical models.

Some background: Group selection refers to the evolution of traits that increase the fitness of whole groups, compared to other groups. These traits are often selectively disadvantageous within groups, creating a conflict between levels of selection. Group selection requires the standard ingredients of natural selection-a population of groups, that vary in their phenotypic properties in a heritable fashion, with consequences for collective survival and reproduction. Standard population genetics models give the impression that groups are unlikely to vary unless they are initiated by small numbers of individuals with minimal migration among groups during their existence. This kind of reasoning turned group selection into a pariah concept in the 1960's , taught primarily as an example of how not to think. I had become convinced that group selection could be revived for smaller, more ephemeral groups that I called "trait groups." Gilpin was suggesting that group selection could also be revived for larger, geographically isolated groups on the basis of complex interactions.

Gilpin focused on the most famous conjecture about group selection, advanced by V.C. Wynne-Edwards in 1962, that animals evolve to avoid overexploiting their resources. Wynne-Edwards had become an icon for everything that was wrong and naïve about group selection. Gilpin boldly proposed that animals could indeed evolve to "manage" their resources, based on non-linearities inherent in predator-prey interactions. As resource exploitation evolves by within-group selection, there is not a gradual increase the probability of extinction. Instead, there is a tipping point that suddenly destabilizes the predator-prey interaction, like falling off a cliff. This discontinuity increases the importance of group selection, keeping the predator-prey interaction in the zone of stability.

I didn't get it. To me, Gilpin's model required a house-of-cards of assumptions, a common criticism leveled against earlier models of group selection. I therefore wrote a tepid review of Gilpin's book. I was probably also influenced by a touch of professional jealousy, as someone who myself was trying to acquire a reputation for reviving group selection!

I didn't get the complexity revolution until I read James Gleik's Chaos: Making A New Science, which I regard as one of the best books ever written about science for a general audience. Suddenly I realized that as complex systems, higher-level biological units such as groups, communities, ecosystems, and human cultures would almost certainly vary in their phenotypic properties and that some of this phenotypic variation might be heritable. Complexity theory became a central theme in my own research.

As one experimental demonstration, William Swenson (then my graduate student) created a population of microbial ecosystems by adding 1 ml of pond water from a single, well-mixed source to test tubes containing 29 ml of sterilized growth medium. This amount of pond water includes millions of microbes, so the initial variation among the test tubes, based on sampling error, was vanishingly small. Nevertheless, within four days (which amounts to many microbial generations) the test tubes varied greatly in their composition and phenotypic properties, such as the degradation of a toxic compound that was added to each test tube. Moreover, when the test tubes were selected on the basis of their properties to create a new generation of microbial ecosystems, there was a response to selection. We could select whole ecosystems for their phenotypic properties (in our case, to degrade a toxic compound), in exactly the same way that animal and plant breeders are accustomed to selecting individual organisms!

These results are mystifying in terms of models that assume simple interactions but make perfect sense in terms of complex interactions. Most people have heard about the famous "butterfly effect" whereby an infinitesimal change in initial conditions becomes amplified over the course of time for a complex physical system such as the weather. Something similar to the butterfly effect was occurring in our experiment, amplifying infinitesimal initial differences among our test tubes into substantial variation over time. A response to selection in the experiments is proof that variation caused by complex interactions can be heritable.

Thanks in large part to complexity theory, evolutionary biologists are once again studying evolution as a multi-level process that can evolve adaptations above the level of individual organisms. I welcome this opportunity to credit Michael Gilpin for the original insight.

Guys lost on unfamiliar streets often avoid asking for directions from locals.  We try to tough it out with map and compass.  Admitting being lost feels like admitting stupidity.  This is a stereotype, but it has a large grain of truth.  It's also a good metaphor for a big overlooked problem in the human sciences. 

We're trying to find our way around the dark continent of human nature.  We scientists are being paid to be the bus-driving tour guides for the rest of humanity.  They expect us to know our way around the human mind, but we don't.

So we try to fake it, without asking the locals for directions.  We try to find our way from first principles of geography ('theory'), and from maps of our own making ('empirical research').  The roadside is crowded with locals, and their brains are crowded with local knowledge, but we are too arrogant and embarrassed to ask the way.  Besides, they look strange and might not speak our language.  So we drive around in circles, inventing and rejecting successive hypotheses about where to find the scenic vistas that would entertain and enlighten the tourists ('lay people', a.k.a. 'tax-payers').  Eventually, our bus-load starts grumbling about tour-guide rip-offs in boring countries.  We drive faster, make more frantic observations, and promise magnificent sights just around the next bend. 

I used to think that this was the best we could do as behavioural scientists.  I figured that the intricacies of human nature were not just dark, but depopulated — that a few exploratory novelists and artists had sought the sources of our cognitive Amazons and emotional Niles, but that nobody actually lived there.

Now, I've changed my mind — there are local experts about almost all aspects of human nature, and the human sciences should find their way by asking them for directions.  These 'locals' are the thousands or millions of bright professionals and practitioners in each of thousands of different occupations.  They are the people who went to our high schools and colleges, but who found careers with higher pay and shorter hours than academic science.  Almost all of them know important things about human nature that behavioural scientists have not yet described, much less understood.  Marine drill sergeants know a lot about aggression and dominance.  Master chess players know a lot about if-then reasoning.  Prostitutes know a lot about male sexual psychology.  School teachers know a lot about child development.  Trial lawyers know a lot about social influence.  The dark continent of human nature is already richly populated with autochthonous tribes, but we scientists don't bother to talk to these experts. 

My suggestion is that whenever we try to understand human nature in some domain, we should identify several groups of people who are likely to know a lot about that domain already, from personal, practical, or professional experience.  We should seek out the most intelligent, articulate, and experienced locals — the veteran workers, managers, and trainers. Then, we should talk with them, face-to-face, expert-to-expert, as collaborating peers, not as researchers 'running subjects' or 'interviewing informants'.  We may not be able to reimburse them at their professional hourly wage, but we can offer other forms of prestige, such as co-authorship on research papers.

For example, suppose a psychology Ph.D. student wants to study emotional adaptations such as fear and panic, that evolved for avoiding predators.  She learns about the existing research (mostly by Clark Barrett at UCLA), but doesn't have any great ideas for her dissertation research.  The usual response is three years of depressed soul-searching, random speculation, and fruitless literature reviews.  This phase of idea-generation could progress much more happily if she just picked up the telephone and called some of the people who spend their whole professional lives thinking about how to induce fear and panic.  Anyone involved in horror movie production would be a good start: script-writers, monster designers, special effects technicians, directors, and editors.  Other possibilities would include talking with:

• Halloween mask designers,
• horror genre novelists,
• designers of 'first person shooter' computer games,
• clinicians specializing in animal phobias and panic attacks,
• Kruger Park safari guides,
• circus lion-tamers,
• dog-catchers,
• bull-fighters,
• survivors of wild animal attacks, and
• zoo-keepers who interact with big cats, snakes, and raptors.

A few hours of chatting with such folks would probably be more valuable in sparking some dissertation ideas than months of library research. 

The division of labor generates wondrous prosperity, and an awesome diversity of knowledge about human nature in different occupations.  Psychology could continue trying to rediscover all this knowledge from scratch.  Or, it could learn some humility, and start listening to the real expertise about human nature already acquired by every bright worker in every factory, office, and mall.

It is a charming concept that humans are in fact able "to change their mind" in the first place. Not that it necessarily implies a change for the better, but at least it does have that positive ring of supposing a Free Will to perform this feat at all. Better, in any case, to be the originator of the changing, rather than having it done to you, in the much less applaudable form of brain washing.

For me, in my own life as I passed the half-century mark, with almost exactly half the time spent in the US and the other in Europe, in-between circling the globe a few times, I can look back on what now seems like multiple lifetimes worth of mind changing.

Here then is a brief point, musing about the field I spent 20 years in: Computer Software. And it is deeper than it may seem at first glance.

I used to think "Software Design" is an art form.

I now believe that I was half-right:
it is indeed an art, but it has a rather short half-life: 
Software is merely a performance art!

A momentary flash of brilliance, doomed to be overtaken by the next wave, or maybe even by its own sequel. Eaten alive by its successors. And time...

This is not to denigrate the genre of performance art: anamorphic sidewalk chalk drawings, Goldsworthy pebble piles or Norwegian carved-ice-hotels are admirable feats of human ingenuity, but they all share that ephemeral time limit: the first rain, wind or heat will dissolve the beauty, and the artist must be well aware of its fleeting glory.

For many years I have discussed this with friends that are writers, musicians, painters and the simple truth emerged: one can still read the words, hear the music and look at the images....

Their value and their appeal remains, in some cases even gain by familiarity: like a good wine it can improve over time. You can hum a tune you once liked, years later. You can read words or look a painting from 300 years ago and still appreciate its truth and beauty today, as if brand new. Software, by that comparison, is more like Soufflé: enjoy it now, today, for tomorrow it has already collapsed on itself. Soufflé 1.1 is the thing to have, Version 2.0 is on the horizon.

It is a simple fact: hardly any of my software even still runs at all!

Back in 1982 I started with a highschool buddy in a garage in the Hollywood hills. With ludicrous limitations we conjured up dreams: three-dimensional charting, displaying sound as time-slice mountains of frequency spectrum data, annotated with perspective lettering... and all that in 32K of RAM on a 0.2Mhz processor. And we did it... a few years later it fed 30 people.

The next level of dreaming up new frontiers with a talented tight team was complex algorithms for generating fractals, smooth color gradients, multi layer bumpmapped textures and dozens of image filters, realtime liquid image effects, and on and on... and that too, worked and this time fed over 300 people. Fifteen products sold many millions of copies - and a few of them still persist to this day, in version 9 or 10 or 11... but for me, I realized, I no longer see myself as a software designer - I changed my mind.

Today, if you have a very large task at hand, one that you calculate might take two years or three... it has actually become cheaper to wait for a couple of generation changes in the hardware and do the whole thing then - ten times faster.

In other words: sit by the beach with umbrella drinks for 15 months and then finish it all at once with some weird beowulf-cluster of machinery and still beat the original team by leaps and bounds. At the start, all we were given was the starting address in RAM where video memory began, and a POKE to FC001101 would put a dot on the screen. Just one dot.

Then you figured out how to draw a line. How to connect them to polygons. How to fill those with patterns. All on a screen of 192x128, ( which is now just "an icon")

Uphill in the snow, both ways.

Now the GPUs are blasting billions of pixels per second and all they will ask is "does it blend?" Pico, Femto, Atto, Zepto, Yocto cycles stored in Giga, Tera, Peta, Exa, Zetta, Yotta cells.

I rest my case about those umbrella drinks.

Do I really just drop all technology and leave computing ? Nahh. QuadHD screens are just around the corner, and as a tool for words, music and images there are fantastic new horizons for me. I am more engaged in it all than ever — alas: the actual coding and designing itself is no longer where I see my contribution. But the point is deeper than just one mans path:

The new role of technology is a serious philosophical point in the long range outlook for mankind. Most decision makers world wide, affecting the entire planet, are technophobes, luddites and noobs beyond belief. They have no vision for the potential, nor proper respect for the risks, nor simple estimation of the immediate value for quality of life that technology could bring. 
Maybe one can change their mind?

I remembered that I once wrote something about this very topic... 
and I found it: 

I changed my mind mostly about changing my mind: 
I used to be all for 'being against it', 
then I was all against 'being for it', 
until I realized: thats the same thing....never mind. 
It's a 'limerickety' little thing from some keynote 12 years ago, but...see.... it still runs : )

I spent a long time believing in the centrality of probability in life and advocating that we should express everything in terms of degrees of credence, with unitary probabilities as a special case for total certainties, and null for total implausibility. Critical thinking, knowledge, beliefs, everything needed to be probabilized. Until I came to realize, twelve years ago, that I was wrong in this notion that the calculus of probability could be a guide to life and help society. Indeed, it is only in very rare circumstances that probability (by itself) is a guide to decision making . It is a clumsy academic construction, extremely artificial, and nonobservable. Probability is backed out of decisions; it is not a construct to be handled in a standalone way in real-life decision-making. It has caused harm in many fields.

Consider the following statement. "I think that this book is going to be a flop. But I would be very happy to publish it." Is the statement incoherent? Of course not: even if the book was very likely to be a flop, it may make economic sense to publish it (for someone with deep pockets and the right appetite) since one cannot ignore the small possibility of a handsome windfall, or the even smaller possibility of a huge windfall. We can easily see that when it comes to small odds, decision making no longer depends on the probability alone. It is the pair probability times payoff (or a series of payoffs), the expectation, that matters. On occasion, the potential payoff can be so vast that it dwarfs the probability — and these are usually real world situations in which probability is not computable.

Consequently, there is a difference between knowledge and action. You cannot naively rely on scientific statistical knowledge (as they define it) or what the epistemologists call "justified true belief" for non-textbook decisions. Statistically oriented modern science is typically based on Right/Wrong with a set confidence level, stripped of consequences. Would you take a headache pill if it was deemed effective at a 95% confidence level? Most certainly. But would you take the pill if it is established that it is "not lethal" at a 95% confidence level? I hope not.

When I discuss the impact of the highly improbable ("black swans"), people make the automatic mistake of thinking that the message is that these "black swans" are necessarily more probable than assumed by conventional methods. They are mostly less probable. Consider that, in a winner-take-all environment such as the one in the arts, the odds of success are low, since there are fewer successful people, but the payoff is disproportionately high. So, in a fat tailed environment, what I call "Extremistan", rare events are less frequent (their probability is lower), but they are so effective that their contribution to the total pie is more substantial.

[Technical note: the distinction is, simply, between raw probability, P[x>K], i.e. the probability of exceeding K, and E[x|x>K], the expectation of x conditional on x>K. It is the difference between the zeroth moment and the first moment. The latter is what usually matters for decisions. And it is the (conditional) first moment that needs to be the core of decision making. What I saw in 1995 was that an out-of-the-money option value increases when the probability of the eventdecreases, making me feel that everything I thought until then was wrong.]

What causes severe mistakes is that, outside the special cases of casinos and lotteries, you almost never face a single probability with a single (and known) payoff. You may face, say, a 5% probability of an earthquake of magnitude 3 or higher, a 2% probability of one of 4 or higher, etc. The same with wars: you have a risk of different levels of damage, each with a different probability. "What is the probability of war?" is a meaningless question for risk assessment.

So it is wrong to just look at a single probability of a single event in cases of richer possibilities (like focusing on such questions as "what is the probability of losing a million dollars?" while ignoring that , conditional on losing more than a million dollars, you may have an expected loss of twenty million, one hundred million, or just one million). Once again, real life is not a casino with simple bets. This is the error that helps the banking system go bust with an astonishing regularity — I've showed that institutions that are exposed to negative black swans, like banks and some classes of insurance ventures, have almost never profitable over long periods. The problem of the illustrative current subprime mess is not so much that the "quants" and other pseudo-experts in bank risk management were wrong about the probabilities (they were), but that they were severely wrong about the different layers of depth of potential negative outcomes. For instance, Morgan Stanley lost about ten billion dollars (so far) while allegedly having foreseen a subprime crisis and executed hedges against it — they just did not realize how deep it would go and had open exposure to the big tail risks. This is routine: a friend who went bust during the crash of 1987, told me: "I was betting that it would happen but I did not know it would go that far".

The point is mathematically simple but does not register easily. I've enjoyed giving math students the following quiz (to be answered intuitively, on the spot). In a Gaussian world, the probability of exceeding one standard deviations is ~16%. What are the odds of exceeding it under a distribution of fatter tails (with same mean and variance)? The right answer: lower, not higher — the number of deviations drops, but the few that take place matter more. It was entertaining to see that most of the graduate students get it wrong. Those who are untrained in the calculus of probability have a far better intuition of these matters.

Another complication is that just as probability and payoff are inseparable, so one cannot extract another complicated component, utility, from the decision-making equation. Fortunately, the ancients with all their tricks and accumulated wisdom in decision-making, knew a lot of that, at least better than modern-day probability theorists. Let us stop to systematically treat them as if they were idiots. Most texts blame the ancients for their ignorance of the calculus of probability — the Babylonians, Egyptians, and Romans in spite of their engineering sophistication, and the Arabs, in spite of their taste for mathematics, were blamed for not having produced a calculus of probability (the latter being, incidentally, a myth, since Umayyad scholars used relative word frequencies to determine authorships of holy texts and decrypt messages). The reason was foolishly attributed to theology, lack of sophistication, lack of something people call the "scientific method", or belief in fate. The ancients just made decisions in a more ecologically sophisticated manner than modern epistemology minded people. They integrated skeptical Pyrrhonian empiricism into decision making. As I said, consider that belief (i.e., epistemology) and action (i.e., decision-making), the way they are practiced, are largely not consistent with one another.

Let us apply the point to the current debate on carbon emissions and climate change. Correspondents keep asking me if it the climate worriers are basing their claims on shoddy science, and whether, owing to nonlinearities, their forecasts are marred with such a possible error that we should ignore them. Now, even if I agreed that it were shoddy science; even if I agreed with the statement that the climate folks were most probably wrong, I would still opt for the most ecologically conservative stance — leave planet earth the way we found it. Consider the consequences of the very remote possibility that they may be right, or, worse, the even more remote possibility that they may be extremely right.

Before I entered the intellectual funnel of graduate school, I used to cook up thought experiments to explain coincidences, such as  running into a person immediately after a random thought of them. This secretive thinking was good mental entertainment, but the demand of forging a serious career in physics research forced me to make peace with such wild speculations.  In my theory of coincidences, non-local interactions as well as a dark form of energy was necessary; absolute science fiction!  Fifteen years later, we now have overwhelming evidence of a 'fifth-force' mediating an invisible substance that the community has dubbed 'dark energy'.   In hindsight, it is of no coincidence that I have changed my mind that nature is non-local. 

Non-local correlations are not common experience to us, thus it is both difficult to imagine and accept.  Often, research in theoretical physics encourages me to keep an open mind; or to not get too attached to ideas that I am deluded into thinking should be correct.   While this has been a constant struggle for me in my scientific career thus far, I have experienced the value of this theoretical ideology weaning process.  After years of wrestling with some of the outstanding problems in the field of elementary particle physics and cosmology, I have been forced to change my mind on this predisposition that has been silently passed on to me by my physics predecessors, that the laws physics are, for the most part, local.

During my first year in graduate school, I came across the famous Einstein, Podosky and Rosen (EPR) thought experiment, which succinctly argue for the inevitable 'spooky action at a distance' in quantum mechanics.   Then came the Aspect experiment that measured the non-local entanglement of photon polarization confirming EPRs expectation that there exist non-local correlations in nature enabled by quantum mechanics (with a caveat of course).   This piece of knowledge had a short life in my education and research career.

Non-locality exited the door of my brain once and for all, after I approached one of my professors, an accomplished quantum field theorist.  He convinced me that non-locality goes away once quantum mechanics properly incorporates causality, through a unification with special relativity; i.e. a theory known as quantum field theory.   With the promise of a sounder career path I invited these, then comforting words, and attempted to master quantum field theory.   Plus, even if non-locality happens, these processes are exceptional events created under special conditions, while most physics is completely local.  Quantum field theory works and it became my new religion.  I have since remained on this comfortable path.

Now that I specialize in the physics of the early universe, I have first hand witnessed the great predictive and precise explanatory powers of Einstein's general relativity, married with quantum field theory to both explain the complete history and physical mechanism for the origin of structures in the universe, all in a seemingly local and causative fashion.  We call this paradigm cosmic inflation and it is deceptively simple.  The universe started out immediately after the big bang from a microscopically tiny piece of space then inflated 'faster than the speed of light'.   Inflation is able to explain our entire complexity of observed universe with the economy of a few equations that involve general relativity and quantum field theory.

Despite its great success inflation has been plagued with conceptual and technical problems.  These problems created thesis projects and inevitably, jobs for a number of young theorists like myself.  Time after time, publication after publication, like a rat on his wheel, we are running out of steam, as the problems of inflation just reappear in some other form.  I have now convinced myself that the problems associated with inflation won't go away unless we somehow include non-locality. 

Ironically, inflation gets ignited by the same form of dark energy that we see permeating the fabric of the cosmos today, except in much greater abundance fourteen billion years ago.  Where did most of the dark energy go after inflation ended?  Why is some of it still around?  Is this omniscient dark energy the culprit behind non-local activity in physical processes?  I don't know exactly how non-locality in cosmology will play itself out, but by its very nature, the physics underlying it will affect 'local' processes.  I still haven't changed my mind on coincidences though.

The appeal of Darwin's theory of evolution — and the horror of it, for some theists — is that it expunges from biology the concept of purpose, of teleology, thereby converting biology into a mechanistic, canonical science. In this respect, the author of The Origin of Species may be said to be the combined Copernicus, Galileo, and Kepler of biology. Just as these astronomers gave us a view of the heavens in which no angels were required to propel the planets in their orbs and the earth was no longer the center of the celestial system, so Darwin showed that no God was needed to design the spider's intricate web and that man is in truth but another animal.

That's how the standard story goes, and it is pretty much what I used to believe, until I read Darwin's later book, his treatise on the evolution of the mental life of animals, including the human species: The Descent of Man. This is the work in which Darwin introduces one of the most powerful ideas in the study of human nature, one that can explain why the capacities of the human mind so extravagantly exceed what would have been required for hunter-gatherer survival on the Pleistocene savannahs. The idea is sexual selection, the process by which men and women in the Pleistocene chose mates according to varied physical and mental attributes, and in so doing "built" the human mind and body as we know it.

In Darwin's account, human sexual selection comes out looking like a kind of domestication. Just as human beings domesticated dogs and alpacas, roses and cabbages, through selective breeding, they also domesticated themselves as a species through the long process of mate selection. Describing sexual selection as human self-domestication should not seem strange. Every direct prehistoric ancestor of every person alive today at times faced critical survival choices: whether to run or hold ground against a predator, which road to take toward a green valley, whether to slake an intense thirst by drinking from some brackish pool. These choices were frequently instantaneous and intuitive and, needless to say, our direct ancestors were the ones with the better intuitions.

However, there was another kind of crucial intuitive choice faced by our ancestors: whether to choose this man or that woman as a mate with whom to rear children and share a life of mutual support. It is inconceivable that decisions of such emotional intimacy and magnitude were not made with an eye toward the character of the prospective mate, and that these decisions did not therefore figure in the evolution of the human personality — with its tastes, values, and interests.  Our actual direct ancestors, male and female, were the ones who were chosen by each other.

Darwin's theory of sexual selection has disquieted and irritated many otherwise sympathetic evolutionary theorists because, I suspect, it allows purposes and intentions back into evolution through an unlocked side door. The slogan memorized by generations of students of natural selection is random mutation and selective retention. The "retention" in natural selection is strictly non-teleological, a matter of brute, physical survival. The retention process of sexual selection, however, is with human beings in large measure purposive and intentional. We may puzzle about whether, say, peahens have "purposes" in selecting peacocks with the largest tails. But other animals aside, it is absolutely clear that with the human race, sexual selection describes a revived evolutionary teleology. Though it is directed toward other human beings, it is as purposive as the domestication of those wolf descendents that became familiar household pets.

Every Pleistocene man who chose to bed, protect, and provision a woman because she struck him as, say, witty and healthy, and because her eyes lit up in the presence of children, along with every woman who chose a man because of his hunting skills, fine sense of humor, and generosity, was making a rational, intentional choice that in the end built much of the human personality as we now know it.

Darwinian evolution is therefore structured across a continuum. At one end are purely natural selective processes that give us, for instance, the internal organs and the autonomic processes that regulate our bodies. At the other end are rational decisions — adaptive and species-altering across tens of thousands of generations in prehistoric epochs.  It is at this end of the continuum, where rational choice and innate intuitions can overlap and reinforce one another, that we find important adaptations that are relevant to understanding the human personality, including the innate value systems implicit in morality, sociality, politics, religion, and the arts. Prehistoric choices honed the human virtues as we now know them: the admiration of altruism, skill, strength, intelligence, industriousness, courage, imagination, eloquence, diligence, kindness, and so forth.

The revelations of Darwin's later work — beautifully explicated as well in books by Helena Cronin, Amotz and Avishag Zahavi, and Geoffrey Miller — have completely altered my thinking about the development of culture. It is not just survival in a natural environment that has made human beings what they are. In terms of our personalities we are, strange to say, a self-made species. For me this is a genuine revelation, as it puts in a new genetic light many human values that have hitherto been regarded as purely cultural.

This was a central part of liberal baby-boomer common sense when I was growing up, especially if you came from a (still) dominant country like Britain. Moreover to show any sense of national feeling — apart from contempt for your national traditions — was a sign that you lacked political sophistication.

I now believe this is mainly nonsense. Nationalism can, of course, be a destructive force and we were growing up in the shadow of its 19th and 20th century excesses. In reaction to that most of the civilized world had, by the mid 20th century, signed up to a liberal universalism (as embodied in the UN charter) that stressed the moral equality of all humans. I am happy to sign up to that too, of course, but I now no longer see that commitment as necessarily conflicting with belief in the nation state. Indeed I think many anti-national liberals make a sort of category error — belief in the moral equality of all humans does not mean that we have the same obligations to all humans. Membership of the political community of a modern nation state places quite onerous duties on us to obey laws and pay taxes, but also grants us many rights and freedoms — and they make our fellow citizens politically "special" to us in a way that citizens of other countries are not. This "specialness" of national citizenship is most vividly illustrated in the factoid that every year in Britain we spend 25 times more on the National Health Service than we do on development aid.

Moreover if the nation state can be a destructive force it is also at the root of what many liberals hold dear: representative democracy, accountability, the welfare state, redistribution of wealth and the very idea of equal citizenship. None of these things have worked to any significant extent beyond the confines of the nation state, which is not to say that they couldn't at some point in the future (indeed they already do so to a small extent in the EU). If you look around at the daily news — contested elections in Kenya, death in Pakistan — most of the bad news these days comes from too little nation state not too much. And why was rapid economic development possible in the Asian tigers but not in Africa? Surely the existence of well functioning nation states and a strong sense of national solidarity in the tigers had something to do with it.

And in rich western countries as other forms of human solidarity — social class, religion, ethnicity and so on — have been replaced by individualism and narrower group identities, holding on to some sense of national solidarity remains more important than ever to the good society. A feeling of empathy towards strangers who are fellow citizens (and with whom one shares history, institutions and social and political obligations) underpins successful modern states, but this need not be a feeling that stands in the way of empathy towards all humans. It just remains true that charity begins at home.

Over the last three years, we've run a project called the Summer of Code, in which we pair up university level software developers with open source software projects. If the student succeeds in fulfilling the goals set forth in their application (which the project has accepted) then they are paid a sum of $4500. We wanted a program that would keep software developers coding over the summer and it would also help out our friends in the world of open source software development.

The passing rate last year was 81%, which means some 700+ students completed their projects to the satisfaction of their mentors.

This last year, we did a cursory study of the code produced by these students and reviewed, among other items, how many lines of code the student produced. The lines of code thing has been done to death in the computer industry, and it's a terrible measure of programmer productivity. It is one of the few metrics we do have and since we make the assumption that if they pass the project then their code has passed muster. So after that the lines of code becomes somewhat more significant than it would normally.

Over the summer of the average student produced 4,000 lines of code with some students producing as much at 10, 14 and even 20 thousand lines. This is an insane amount of code written weather you measure by time or by money. By some measures this means the students are anywhere between 5 and 40 times as productive as your 'average' employed programmer.  This code, mind you, was written by a student who is almost always geographically separated from their mentor by at least 3 time zones and almost never has a face to face meeting with their mentor.

This is an absurd amount of productivity for a student or,  heck, anyone, writing code. This is often production and user-ready code being produced by these students. It's really something to see and made me revise what I consider a productive developer to be and what indeed I should expect from the engineers that work for and with me.

But, and here's the thing I changed my mind about, is the tradeoff for silly high productivity that I have to run my projects the way we run the Summer of Code? Maybe. Can I keep my hands off and let things run their course? Is the team strong enough to act as this kind of mentoring to each other? I now think the answer is that yes, they can run each other better than I can run them. So let's see what letting go looks like. Ask me next year? Let's hope next years question is 'what chance are you least regretful you took?' and I can talk about this then!

I used to think that languages and cultures shape the ways we think. I suspected they shaped they ways we reason and interpret information.  But I didn't think languages could shape the nuts and bolts of perception, the way we actually see the world.  That part of cognition seemed too low-level, too hard-wired, too constrained by the constants of physics and physiology to be affected by language.

Then studies started coming out claiming to find cross-linguistic differences in color memory.  For example, it was shown that if your language makes a distinction between blue and green (as in English), then you're less likely to confuse a blue color chip for a green one in memory.  In a study like this you would see a color chip, it would then be taken away, and then after a delay you would have to decide whether another color chip was identical to the one you saw or not.

Of course, showing that language plays a role in memory is different than showing that it plays a role in perception.  Things often get confused in memory and it's not surprising that people may rely on information available in language as a second resort.  But it doesn't mean that speakers of different languages actually see the colors differently as they are looking at them.  I thought that if you made a task where people could see all the colors as they were making their decisions, then there wouldn't be any cross-linguistic differences.

I was so sure of the fact that language couldn't shape perception that I went ahead and designed a set of experiments to demonstrate this.  In my lab we jokingly referred to this line of work as "Operation Perceptual Freedom."  Our mission: to free perception from the corrupting influences of language.

We did one experiment after another, and each time to my surprise and annoyance, we found consistent cross-linguistic differences.  They were there even when people could see all the colors at the same time when making their decisions.  They were there even when people had to make objective perceptual judgments.  They were there when no language was involved or necessary in the task at all.  They were there when people had to reply very quickly.  We just kept seeing them over and over again, and the only way to get the cross-linguistic differences to go away was to disrupt the language system.  If we stopped people from being able to fluently access their language, then the cross-linguistic differences in perception went away.

I set out to show that language didn't affect perception, but I found exactly the opposite.  It turns out that languages meddle in very low-level aspects of perception, and without our knowledge or consent shape the very nuts and bolts of how we see the world.

I've come to reject the common "SETI" (search for extraterrestrial intelligence) wisdom that there must be millions of technology capable civilizations within our "light sphere" (the region of the Universe accessible to us by electromagnetic communication).  The Drake formula provides a means to estimate the number of intelligent civilizations in a galaxy or in the universe. Essentially, the likelihood of a planet evolving biological life that has created sophisticated technology is tiny, but there are so many star systems, that there should still be many millions of such civilizations. Carl Sagan's analysis of the Drake formula concluded that there should be around a million civilizations with advanced technology in our galaxy, while Frank Drake estimated around 10,000. And there are many billions of galaxies. Yet we don't notice any of these intelligent civilizations, hence the paradox that Fermi described in his famous comment. So where is everyone?

We can readily explain why any one of these civilizations might be quiet. Perhaps it destroyed itself. Perhaps it is following the Star Trek ethical guideline to avoid interference with primitive civilizations (such as ours). These explanations make sense for any one civilization, but it is not credible, in my view, that every one of the billions of technology capable civilizations that should exist has destroyed itself or decided to remain quiet. 

The SETI project is sometimes described as trying to find a needle (evidence of a technical civilization) in a haystack (all the natural signals in the universe). But actually, any technologically sophisticated civilization would be generating trillions of trillions of needles (noticeably intelligent signals). Even if they have switched away from electromagnetic transmissions as a primary form of communication, there would still be vast artifacts of electromagnetic phenomenon generated by all of the many computational and communication processes that such a civilization would need to engage in.  

Now let's factor in what I call the "law of accelerating returns" (the inherent exponential growth of information technology). The common wisdom (based on what I call the intuitive linear perspective) is that it would take many thousands, if not millions of years, for an early technological civilization to become capable of technology that spanned a solar system. But because of the explosive nature of exponential growth, it will only take a quarter of a millennium (in our own case) to go from sending messages on horseback to saturating the matter and energy in our solar system with sublimely intelligent processes.

The price-performance of computation went from 10-5 to 108 cps per thousand dollars in the 20th century. We also went from about a million dollars to a trillion dollars in the amount of capital devoted to computation, so overall progress in nonbiological intelligence went from 10-2 to 1017 cps in the 20th century, which is still short of the human biological figure of 1026 cps. By my calculations, however, we will achieve around 1069 cps by the end of the 21st century, thereby greatly multiplying the intellectual capability of our human-machine civilization.  Even if we find communication methods superior to electromagnetic transmissions we will nonetheless be generating an enormous number of intelligent electromagnetic signals.  

According to most analyses of the Drake equation, there should be billions of civilizations, and a substantial fraction of these should be ahead of us by millions of years. That's enough time for many of them to be capable of vast galaxy-wide technologies. So how can it be that we haven't noticed any of the trillions of trillions of "needles" that each of these billions of advanced civilizations should be creating?

My own conclusion is that they don't exist. If it seems unlikely that we would be in the lead in the universe, here on the third planet of a humble star in an otherwise undistinguished galaxy, it's no more perplexing than the existence of our universe with its ever so precisely tuned formulas to allow life to evolve in the first place.

Recently, I've had to change my mind about the very nature of knowledge because of an obvious, but extremely weird fact about children - they pretend all the time. Walk into any preschool and you'll be surrounded by small princesses and superheroes in overalls - three-year-olds literally spend more waking hours in imaginary worlds than in the real one. Why? Learning about the real world has obvious evolutionary advantages and kids do it better than anyone else. But why spend so much time thinking about wildly, flagrantly unreal worlds? The mystery about pretend play is connected to a mystery about adult humans - especially vivid for an English professor's daughter like me. Why do we love obviously false plays and novels and movies?

The greatest success of cognitive science has been our account of the visual system. There's a world out there sending information to our eyes, and our brains are beautifully designed to recover the nature of that world from that information. I've always thought that science, and children's learning, worked the same way. Fundamental capacities for causal inference and learning let scientists, and children, get an accurate picture of the world around them - a theory. Cognition was the way we got the world into our minds.

But fiction doesn't fit that picture - its easy to see why we want the truth but why do we work so hard telling lies? I thought that kids' pretend play, and grown-up fiction, must be a sort of spandrel, a side-effect of some other more functional ability. I said as much in a review in Science and got floods of e-mail back from distinguished novel-reading scientists. They were all sure fiction was a Good Thing - me too, of course, - but didn't seem any closer than I was to figuring out why.

So the anomaly of pretend play has been bugging me all this time. But finally, trying to figure it out has made me change my mind about the very nature of cognition itself.

I still think that we're designed to find out about the world, but that's not our most important gift. For human beings the really important evolutionary advantage is our ability to create new worlds. Look around the room you're sitting in. Every object in that room - the right angle table, the book, the paper, the computer screen, the ceramic cup was once imaginary. Not a thing in the room existed in the pleistocene. Every one of them started out as an imaginary fantasy in someone's mind. And that's even more true of people - all the things I am, a scientist, a philosopher, an atheist, a feminist, all those kinds of people started out as imaginary ideas too. I'm not making some relativist post-modern point here, right now the computer and the cup and the scientist and the feminist are as real as anything can be. But that's just what our human minds do best - take the imaginary and make it real. I think now that cognition is also a way we impose our minds on the world.

In fact, I think now that the two abilities - finding the truth about the world and creating new worlds-are two sides of the same coins. Theories, in science or childhood, don't just tell us what's true - they tell us what's possible, and they tell us how to get to those possibilities from where we are now. When children learn and when they pretend they use their knowledge of the world to create new possibilities. So do we whether we are doing science or writing novels. I don't think anymore that Science and Fiction are just both Good Things that complement each other. I think they are, quite literally, the same thing.

What I've changed my mind about is that the public is wedded to obsolete 1970s GUIs & info mgmt forever — PARC's desktop & Bell Labs' Unix file system. I'll give two example from my own experience. Both constitute long term ideas of mine and might seem like self-promotion, but my point is that as a society we don't have the patience to develop fully those big ideas that need time to soak in.

I first described a GUI called "lifestreams" in the Washington Post in 1994. By the early 2000s, I thought this system was dead in the water, destined to be resurrected in a grad student's footnote around the 29th century, The problem was (I thought) that Lifestreams was too unfamiliar, insufficiently "evolutionary" and too "revolutionary" (as the good folks at ARPA like to say [or something like that]); you need to go step-by-step with the public and the industry or you lose.

But today "lifestreams" are all over the net (take a look yourself), and I'm told that "lifestreaming" has turned into a verb at some recent Internet conferences. According to ZDnet.com, "Basically what's important about the OLPC [one laptop per child], has nothing to do with its nominal purposes and everything to do with its interface. Ultimately traceable to David Gelernter's 'Lifestreams' model, this is not just a remake of Apple's evolution of the original work at Palo Alto, but something new."

Moral: the public may be cautions but is not reactionary.

In a 1991 book called Mirror Worlds, I predicted that everyone would be putting his personal stuff in the Cybersphere (AKA "the clouds"); I said the same in a 2000 manifesto on Edge called "The 2nd Coming", & in various other pieces in between. By 2005 or so, I assumed that once again I'd jumped the gun, by too long to learn the results pre-posthumously — but once again this (of all topics) turns out to hot and all over the place nowadays. "Cloud computing" is the next big thing: What does this all prove? If you're patient, good ideas find audiences. But you have to bevery patient.

And if you expect to cash in on long-term ideas in the United States, you're certifiable.

This last point is a lesson I teach my students, and on this item I haven't (and don't expect to) change my mind. But what the hell? It's New Year's, and there are worse things than being proved right once in a while, even if it's too late to count.

I've long considered myself as working at the boundary between physical science and computer science; I now believe that that boundary is a historical accident and does not really exist.

There's a sense in which technological progress has turned it into a tautological statement. It's now possible to store data in atomic nuclei and use electron bonds as logical gates. In such a computer the number of information-bearing degrees of freedom is on the same order as the number of physical ones; it's no longer feasible to account for them independently. This means that computer programs can, and I'd argue must, look more like physical models, including spatial and temporal variables in the density and velocity of information propagation and interaction. That shouldn't be surprising; the canon of computer science emerged a few decades ago to describe the available computing technology, while the canon of physics emerged a few centuries ago to describe the accessible aspects of nature. Computing technology has changed more than nature has; progress in the former is reaching the limits of the latter.

Conversely, it makes less and less sense to define physical theories by the information technology of the last millenium (a pencil and piece of paper); a computational model is every bit as fundamental as one written with calculus. This is seen in frontiers of research in nonlinear dynamics, and quantum field theories, and black hole thermodynamics, that look more and more like massively parallel programming models. However, the organization of research has not yet caught up with this content; many of the pioneers doing the work are in neither Physics nor Computer Science departments, but are scattered around (and off) campus. Rather than trying to distinguish between programming nature and the nature of programming, I think that it makes more sense to recognize not just a technology or theory of information, but a single science.

If asked years ago whether I believed in God, my answer would have gone something like this: "I believe there's something…" This response leaves enough wiggle room for a few quasi-religious notions to slip comfortably through. I no longer believe that my soul is immortal, that the universe sends me messages every now and then, or that my life story will unfold according to some inscrutable plan. But it is more like knowing how and why a perceptual illusion is deceiving my evolved senses than it is becoming immune to the illusion altogether. 
Here's a snapshot of how these particular illusions work:

Psychological Immortality
There's a scene in Gide's The Counterfeiters where a suicidal man puts a pistol to his temple but hesitates for fear of the noise from the blast. Similarly, a group of college students who rejected the idea that consciousness survives death nonetheless told me that someone who'd died in a car accident would know he was dead. "There's no afterlife," one participant said. "He sees that now." 
In wondering what it's like to be dead, our psychology responds by running mental simulations using previous states of consciousness. The trouble is that death is not like anything we've ever experienced — orcan experience. (What's it like to be conscious yet unconscious at the same time?) I doubt you'd find anyone who believes less in the afterlife, yet I have a very real fear of ghosts and I feel guilty for not visiting my mother's grave more often. 

Symbolic Meaning of Natural Events
Psychologist Becky Parker and I told a seven-year-old that an invisible princess was in the room with her. The task was to find a hidden ball by placing her hand on top of the box she thought it was inside. If you change your mind, we said, just move your hand to the other box. Now, Princess Alice likes you and she's going to help you find the ball. "I don't know how she's going to tell you," said Becky, "but somehow she'll tell you if you pick the wrong box."

The child picked a box, held her hand there, and after 15 seconds the box opened to reveal the ball (there were two identical balls). On the second trial, as soon as the girl chose a box, a picture crashed to the ground, and the child moved her hand to the other box. In doing so, she responded just like most other seven-year-olds we tested. They didn't need to believe in Princess Alice to see the picture falling as a sign. In fact, if scepticism can be operationally measured by the degree of tilt in rolling eyes, many of them could be called sceptics.
More surprising was that slightly younger children, the credulous five-year-olds, didn't move their hands, and when asked why the picture fell, they said things like "I don't know why she did it, she just did it." They saw Princess Alice as running about making things happen, not as a communicative partner. To them, the events had nothing to do with their behaviour. Finally, the three-year-olds we tested simply shrugged their shoulders and said that the picture was broken. Princess Alice who?

Seeing signs in natural events is a developmental accomplishment rather than the result of a gap in scientific knowledge. To experience an illusion, the psychological infrastructure must first be in place. Whenever I hear mayors blaming hurricanes on drug use or evangelicals attributing tsunamis to homosexuality, I think of Princess Alice. Still, after receiving bad news my first impulse is to ask myself "why?"  Even for someone like me, scientific explanations just don't scratch the itch like supernatural ones. 

Personal Destiny
Jean-Paul Sartre, the atheistic existentialist, observed that he couldn't help but feel as though a divine hand had guided his life. "It contradicts many of my other ideas," he said. "But it is there, floating vaguely. And when I think of myself I often think rather in this way, for want of being able to think otherwise."

My own atheism is not as organic as was Sartre's. Only scientific evidence and eternal vigilance have enabled me to step outside of this particular illusion of personal destiny. Psychologists now know that human beings intuitively reason as though natural categories exist foran intelligently designed purpose. Clouds don't just exist, say kindergartners, they're there for raining.

Erring this way about clouds is one thing, but when it colours our reasoning about our own existence, that's where this teleo-functional bias gets really interesting. The illusion of personal destiny is intricately woven together with other quasi-religious illusions in a complex web that researchers have not even begun to pull apart. My own private thoughts remain curiously saturated with doubts about whether I'm doing what I'm "meant" for.

Some beliefs are arrived at so easily, held so deeply, and divorced so painfully that it seems unnatural to give them up. Such beliefs can be abandoned when the illusions giving rise to them are punctured by scientific knowledge, but a mind designed by nature cannot be changed fundamentally. I stopped believing in God long ago, but he still casts a long shadow.