THE TWO STEVES (Part I)

A Debate
Steven Rose, Steven Pinker [3.24.98]
Topic:
Introduction By: John Brockman

On January 21st, Steven Pinker and Steven Rose debated each other in an event chaired by Susan Blackmore and held at London University's Institute of Education under the sponsorship of Dillon's and The London Times. Over a thousand people attended-and the event was sold out within three days of being announced. I wish I had been there.

No two individuals better illustrate my notion of a "third culture" which "consists of those scientists and other thinkers in the empirical world who, through their work and expository writing, are taking the place of the traditional intellectual in rendering visible the deeper meanings of our lives, redefining who and what we are."

In this culture, there is no canon or accredited list of acceptable ideas. The strength of the third culture is precisely that it can tolerate disagreements about which ideas are to be taken seriously. Unlike previous intellectual pursuits, the achievements of the third culture are not the marginal disputes of a quarrelsome mandarin class: they will affect the lives of everybody on the planet.

The Two Steves have serious disagreements. But whether it's Steve Pinker weighing forth on the notion that the "problems for our ancestors were subtasks of one big problem for their genes" or Steve Rose asserting that "it is in the nature of living systems to be radically indeterminate, to continually construct their-our-own futures," their debate, their disagreement sharpens and clarifies.

The complex structure of the mind is the subject of this book. Its key idea can be captured in a sentence: The mind is a system of organs of computation, designed by natural selection to solve the kinds of problems our ancestors faced in their foraging way of life, in particular, understanding and outmaneuvering objects, animals, plants, and other people. The summary can be unpacked into several claims. The mind is what the brain does; specifically, the brain processes information, and thinking is a kind of computation. The mind is organized into modules or mental organs, each with a specialized design that makes it an expert in one arena of interaction with the world. The modules' basic logic is specified by our genetic program. Their operation was shaped by natural selection to solve the problems of the hunting and gathering life led by our ancestors in most of our evolutionary history. The various problems for our ancestors were subtasks of one big problem for their genes, maximizing the number of copies that made it into the next generation.

Steven Pinker
From How the Mind Works 
 



 

(My task is to) offer an alternative vision of living systems, a vision which recognizes the power and role of genes without subscribing to genetic determinism, and which recaptures an understanding of living organisms and their trajectories through time and space as lying at the centre of biology. It is these trajectories that I call lifelines. Far from being determined, or needing to invoke some non-material concept of free will to help us escape the determinist trap, it is in the nature of living systems to be radically indeterminate, to continually construct their-our-own futures, albeit in circumstances not of our own choosing.

Steven Rose
From Lifelines: Biology Beyond Determinism 
 



STEVEN PINKER is professor in the Department of Brain and Cognitive Sciences at MIT; director of the McDonnell-Pew Center for Cognitive Neuroscience at MIT; author ofLanguage Learnability and Language Development; Learnability and Cognition; The Language Instinct; andHow the Mind Works.

STEVEN ROSE, neurobiologist, is Professor of Biology and Director, Brain and Behaviour Research Group, The Open University; author of Lifelines; The Making Of Memory; coauthor of Not In Our Genes; editor of From Brains To Consciousness.

SUSAN BLACKMORE, Senior Lecturer in Psychology at the University of the West of England, Bristol, columnist for the Independent, and author of In Search of the Light and the forthcoming The Meme Machine.

Thanks to Dillon's and the London Times for granted permission for transcribing and publishing the debate.

SUSAN BLACKMORE: Before we begin I would like to say a few words about what this debate is, and is not, all about. First it is not pro- or anti-evolution. Both our speakers are committed to the idea that our bodies, our brains and our minds got here by evolution. It is not about moral issues. Neither of our speakers will commit the naturalistic fallacy-that is confusing the way things are with the way we want them to be. If we discover that humans are naturally aggressive or greedy, this does not mean that we have to accept that as right.

It is not a debate about nurture vs nature. Both Pinker and Rose would agree that genes and environment interact in all evolutionary processes and this is not the focus of their disagreement.

What divides them is that Steven Pinker has a view of the underlying function of our minds that is quite different from Stephen Rose's. Pinker is an ultra-Darwinist and therefore believes that the ultimate function of our minds is all to do with passing on our genes-not that everything we do now benefits our genes but that our minds and behaviour were designed by and for the genes.

For Rose, by contrast, the underlying functions, and the motivations for what we do, lie more in the individual. He emphasizes the human being in his or her entire life-their "lifeline". Another important difference is that for Pinker the mind is modular-like the body is. It consists of a lot of different bits and pieces that carry out their functions relatively independently. Whereas for Rose that mechanistic reductionist view misses out on the unity of conscious purpose of an individual human being. So, you can see that tonight's debate concerns the crucial issues of human identity, consciousness, and even free will.

- Susan Blackmore

STEVEN PINKER: Thank you. I'll have to begin by apologizing TO a number of you who may have come under false pretenses. I have an ad for tonight's forum that says that "Professor Pinker is going to argue that what people do is largely determined by their genes, but Professor Rose believes that human beings are able to shape their own lives." Actually, I DON'T believe that what people do is controlled by their genes. And i don't disagree with Professor Rose's statements that human beings are able to control our own lives, that organisms play an active role in their own destiny, and that we have the ability to construct our own futures. The question is not whether those statements are false. The question is whether those statements are BANAL.

OF COURSE we can control our own lives and control our own destinies. For me the question is: "What is it about our minds that ALLOWS us to control our own lives; in particular, that allows us to control our own lives in ways that are different from the way, say, a cat or a monkey can. That's what my book "How the Mind Works" is about, and tonight I'll briefly explain the approach I take in the book-sometimes called evolutionary psychology-and contrast it with what I take to be Professor Rose's approach.

As I said, I don't believe that behavior is controlled by the genes. I believe that behavior is controlled by beliefs and desire. Why did Bill just get on the bus? To answer that question, you don't have to put Bill's head in a brain scanner, and you certainly don't have to do DNA testing on him. Your best bet would be to ask him-and Bill might say something like, "I want to visit my grandmother, and I know that the bus will take me there." No answer will do as well as that one. If Bill hated the sight of his grandmother, or if he knew that the route had changed, his body would not be on that bus. Now this raises a problem. The beliefs and desires that are the best explanation for Bill's behavior are colorless, odorless, tasteless nothings; nonetheless they're as potent a cause of behavior as one billiard ball clacking into another. This is the ancient mind-body problem, and Professor Rose and I agree that the answer is to be sought in material terms; there isn't any immaterial soul or spook or spirit that magically pulls the levers of behavior.

One of the main points of How the Mind Works is that we can answer this question in material terms by interpreting beliefs and desires as a kind of computation. Roughly, beliefs are a kind of information, represented in the brain the way any piece of matter can represent information; desires are goals, that work in the same way as goal states in artificial intelligence programs; the mind, therefore, performs computation. It's not, of course, like the kind of computation done in a digital computer, for many reasons; rather, the elementary data representations and goal states that cause our behavior are implemented as neural networks and ultimately can be tied to the underlying neurophysiology.

Professor Rose, in his book Lifelines, argues strenuously against the doctrine of reductionism. My approach is most definitely not reductionist in the bad sense of trying to explain everything in terms of the smallest units of analysis. I believe that the psychological level of explanation, in terms of beliefs and desires, can be tied to a computational level, in terms of representation and processes, which in turn can be tied to the neural level, of synapses and neural firing. It IS reductionist in the good sense of not allowing a ghost in the machine; that is, any special process at the psychological level that can't be tied ultimately to the physical level. The reductionism I embrace simply states that the elementary units at one level of analysis can be translated into complicated interactions at the next level of analysis.

The next question that arises is WHY we have the kinds of thoughts and feelings that we do. I suggest an important source of information is in the process that gave rise to the brain, namely the evolutionary process, and in particular, the mechanism of natural selection. Let me explain.

How do we understand complex adaptive design in the living world? For example, the vertebrate eye is an intricately complex device, with a lens and a cornea that focus light on a light-sensitive layer of tissue, with an iris that opens and closes in response to the light level, and many other delicately arranged structures. For at least a century we've explained signs of apparent engineering design in the natural world by invoking Darwin's theory of natural selection-the only physical explanation of how good design could come about in the living world. There's no controversy that natural selection is a fundamental source of our understanding of the anatomy of the eye.

But of course the eye is useless without a BRAIN to receive the information coming in from the retina. The signals from the eye are not just dumped onto a blank slate. Rather, there are highly structured circuits that process the information coming from the eye. Now, there are countless signal processing operations that one could imagine being applied to the visual input in principle. But what the brain does is not just any old processing. For example, the visual system of the brain is not like a screen-saver, where it doesn't matter what pattern is displayed, as long as there is a pattern. Rather, we understand visual processing as having the function of constructing an accurate representation of the world: the objects that are out there, their 3-D arrangement, the material that the objects are made of, and so on. And this function is systematically related to the goal of perception, which is to keep the organism from falling off cliffs and bumping into walls and getting eaten by predators.

For over a century, perception has been understood within psychology in adaptationist terms: as a product of the process of natural selection. And perception is, by all accounts, the most successful part of psychology, the one that's closest to a rigorous science.

I believe that this logic can be extended. We obviously don't just see the world, but actively INTERPRET it. Just as there exist complex perceptual faculties that construct an interpretation of the world from a retinal image, there exist complex COGNITIVE faculties. I think we're equipped, for example, with intuitions about the physical world, which allow us to understand inanimate objects; with an intuitive sense of biology, which allows us to figure out how the living world works; with an intuitive psychology, which allows us to be social creatures and interpret other people's behavior in terms of their beliefs and desires; with a sense of number and a sense of space; and with a language faculty that ties us together socially and allows us to exchange information.

I review in the book a variety of kinds of evidence for these different faculties of the mind. One kind of evidence is the sheer engineering complexity that goes into mental feats that we take for granted. Human engineers have not been able to design robots that duplicate common sense and visual perception and motor control and language, because the kinds of things the brain does are so sophisticated that we are only beginning to figure out how they work. A second source of evidence is cross-cultural ethnographic surveys. The faculties that I argue for can be seen in the behavior of people in all cultures. A third source of evidence is precocious development in the infant. There are ingenious experimental methodologies that have discovered that babies have a precocious understanding that the world is made up of objects and minds and living things. Finally, there is evidence from neural dissociations-the results of studies from the neuropsychology lab showing that our different intuitions about living things versus physical objects versus other people can be dissociated in neurological disease-where a patient, say, preserves the ability to name living things, but loses the ability to name man-made objects, or vice versa.

Of course, people aren't like Mister Spock, pure intellects that reason abstractly about the world. In addition to our beliefs, we have DESIRES: emotions that guide our behavior. And as with the case of perception, many of the emotions have long been profitably analyzed as adaptations. Fear for example has been studied for many years, and since the time of Walter Cannon in the '30s, it's been recognized as an adaptation that prepares an organism to cope with danger. Evidence includes the fact that the universal stimuli for fear are ancestral dangers such as heights, venomous animals, confinement, and deep water; the fact that the physiological component of such as the release of adrenalin and an increase in heartrate, prime the organism to cope with a danger by fleeing or otherwise dealing with it; the fact that fear can be shown to be tied to ecologically measurable dangers-animals that evolve on islands without predators lose their sense of fear and are therefore sitting ducks when the islands are invaded by predators. Similarly, sexual desire is uncontroversially an adaptation. It is no mystery why most people would rather make love with an attractive partner than to get a slap on the belly with a wet fish. Sexual desire leads causally to reproduction.

In How the Mind Works, I argue that similar analyses can profitably be applied to other emotions. I think we have well-engineered neural systems for emotions of disgust, happiness, anger, guilt, love of children, love of spouses, love of siblings, and so on.

How does one argue that these emotions really do have a biological function? In the case of fear, we can appeal to the laws of physics: it's a physical fact that a body that falls off a cliff will tend not to live to reproduce. In the case of social emotions we have to look to another body of knowledge to make the argument, and very often is the analysis of inclusive fitness and reciprocity, which can be summed up in Richard Dawkins' metaphor of the selfish gene. To simplify: if you want to ask why people have built into them a love of their family, their children, their parents, and their siblings, the answer is that any gene that fosters such emotions would be protecting and nurturing copies of itself inside the loved one. Just as a gene for fear can be selected because it's less likely to end up at the bottom of a cliff, a gene for love of children can be selected because it's more likely to end up in the body of grandchildren, and therefore to end up with us today.

Now Professor Rose, in his book Lifelines, argues strenuously against the expression "a gene for x", such as a gene for love of family. He makes a number of points I completely agree with, such as that genes don't cause behavior in any linear or direct sense. What I mean by "a gene for X," and what ALL evolutionary theorists mean by "a gene for X," is simply a gene that, in comparison with its alternative allele, averaged over the other genes that it appears with in bodies, and averaged over the environments in appears in, probablistically leads to more behavior X-say, being solicitous to one's children. That's all that "a gene for X" means, and that definition is completely consistent with all of the arguments about genetics in Lifelines. It does not imply that genes directly cause behavior; it's simply a shorthand.

A second caveat is that the idea of the selfish gene does not imply that people are deep down fundamentally selfish. Genes are not the unconscious mind. The way to interpret the expression "selfish gene" is that it's useful to calculate the effects of genes on their own fate by thinking of them as metaphorically selfish. Sometimes the most (metaphorically) selfish thing that a gene can do is to build an organism that's unselfish. So there's no contradiction between saying that selfish genes are part of the explanation for why we have the emotions that we do, and that some of the emotions themselves don't have a trace of selfishness in them.

The third caveat is that I certainly don't believe that everything that we do or feel is adaptive. Professor Rose refers to "ultra-Darwinians" and "Darwinian fundamentalists" who believe that every trait of an organism is adaptive. The ultra-Darwinian is a mythical creature; there aren't any. I believe that SOME aspects of what we think and feel are adaptive; I don't believe that ALL aspects of what we think and feel are adaptive. In particular, in the book I argue that such momentous human activities as dreams, religion, art, music, written language, school math, and school science are not adaptations, but instead are by-products of adaptations.

Why do I think that this is a valuable approach? In the book I show that it has led to new understanding of dozens of topics in psychology. It's spawned an enormous amount of new research in the psychology laboratory, in ethnographic research, and in many other areas, which I don't have time to review now. One such finding was alluded to in the newspaper ad for this forum: there's new evidence that many aspects of what parents do in bringing up their children have no long-term effects on the personality of the children. It's a finding that was predicted by evolutionary theory, and I think it's one of the most important findings in the history of psychology. I can't say any more about it now, but if there's curiosity I can address it in the question period.

Finally, I'd like to talk about the alternative approach suggested by Professor Rose. In Lifelines, Professor Rose suggests that 20th century biology is rotten at the core. It's determinist and reductionist, and is inspired by, and helps to prop up, capitalism and patriarchy. Most of the scientific content of the book itself is a lucid and fascinating overview of the spectacular discoveries of 20th century biology, and Professor Rose presents alternative interpretations of many of those discoveries.

However, as he points out, the discoveries themselves were all done under the standard determinist, reductionist paradigm of biology that he rejects. And many of the arguments in the book try to convince us that scientists such as James Watson, Francis Crick, and Louis Wolpert are not properly interpreting their own discoveries. I find it hard to escape the feeling that much of Professor Rose's approach just REDESCRIBES standard biology with new jargon: words like "autopoiesis" and "homeodynamics" and "self-construction."

I think that there's something conspicuously missing from Professor Rose's approach. It's the sense of AHA! The sense that there's a new insight into problems such asHow the Mind Works, a sense that something formerly mysterious is now comprehensible, a question that inspires research that turns up surprising new findings.

I think this is especially noticeable in the discussions in the book on the human mind and human behavior. The book contains many discussions of hypotheses about human psychology, but virtually all of them are negative: Richard Dawkins and E. O. Wilson are WRONG, WRONG, WRONG!! I scoured the book for anything positive: any new hypothesis about How the Mind Works. In the entire book, I only came up with two. One of them is the suggestion that racism is a cause of schizophrenia, on page 104. This hypothesis is not based, as far as I can tell, on any theory or research, but rather is a consequence of a certain political view. I think it's fair to say that there is no evidence whatsoever that it is true.

The other suggestion is from page 68, in which Professor Rose talks about the metaphors and analogies that we use in science, a point that I completely agree with. But then he says that "the metaphors and analogies that we find attractive are laden with cultural values and expectations that come from outside our science. They inevitably-inevitably!-reflect our experience as directors of companies, or as sacked workers, as men executives, or women child-carers, as white racists, or black footballers. That is they are not and cannot be free from ideology."

Now this raises three questions in my mind. One is: if the ideas that we find attractive are "inevitable," how can that be reconciled with his idea that "we play an active part in our own destiny?" That seems to be an area in our destiny where, according to Professor Rose, we DON'T play an active part. It seems to me to be a strikingly DETERMINISTIC thesis.

The second question is, what is the evidence that this is the case? I don't know of any, but I know of some evidence that it's NOT the case. One field that I'm familiar with, evolutionary psychology, has been attractive to all kinds of people, from members of the British aristocracy to sons of Marxist labor leaders, and it is attractive to men and women in equal numbers. Furthermore I do know of one quantitative study of whether one's social class and social background affect one's acceptance of scientific ideas, namely the data from Frank Sulloway on acceptance versus resistance to revolutionary ideas in science. Sulloway actually looked at scientific revolutions such as Darwinism, and found that there was no correlation between social class and one's willingness to accept new scientific ideas.

Finally there's a political dimension to Professor Rose's claim. Lifelines, from beginning to end, talks about the harmful political consequences that Professor Rose sees in the attempts to relate biology to psychology. The Holocaust is mentioned in the very first paragraph, and throughout the book we are reminded of the way in which these ideas have been distorted by the Nazis and other racists in the 19th and 20th centuries. And Professor Rose adds, "this history cannot be transcended."

But there have, unfortunately, been several holocausts in this century. Some of them have taken place in the Soviet Union, China, and Cambodia, and many of them can be clearly related to the idea that opinions are a product of one's social class, and therefore, rather than being debated, the proponents of them should be "reeducated" or worse. I don't think this necessarily taints the particular opinions, but it is only fair to bring into a discussion that tries to criticize the ideas of the other side for their supposed political implications.

So if these two hypotheses about the mind are the best that Professor Rose's "dialectical biology" can do, I would like to suggest that it is not a particularly promising way to understand How the Mind Works. Thank you.

STEVEN ROSE: There are I suppose a number of possible ways you can interpret what it is we're doing here this evening. One, which would be apparent to anyone who's looked at Lifelines and How the Mind Works is that Steve and I share a literary agent, a publisher, and you could make a straight-forwardly economically determinist argument that we're here to sell our books. An alternative argument would be that we write books rather as peacocks extend their tails, and that is that it's a way of demonstrating-rather than flashing our genitals at you-that we have actually rather good genes. This would in a sense be a version of the ultra-Darwinist argument.

There is another way of looking at it which explains I suspect more seriously why we're all here, and that is that the issues that we have to discuss this evening run far deeper than modern science, they go right the way back through centuries of debate, beyond Darwin, back through, certainly, a good chunk of the Judeo-Christian tradition; they are, as Susan said at the beginning, about determinism and free will, and how one understands the living world that there is around us, and it's those issues I want to discuss. But I do want to say one other thing as well-just as Steve began his talk by trying to ask why someone got on a bus. All three of the possible alternative explanations that I've given you could be right. They are not necessarily mutually incompatible. That is, as Mary Midgley puts it, we live in one world, but a big one, and we live in a world in which there are multiple possible legitimate explanations of things that we're trying to study. There are also false explanations of the things that we're trying to study, and in trying to argue for plurality, as I will do this evening, I don't want to depart for one moment from my claim about the errors of some of those views that I disagree with.

I've got two tasks here this evening: showing where I disagree with Steve Pinker, and proposing in more detail the alternative viewpoints that I take in Lifelines and The Making of Memory. Steve said there wasn't much aboutHow the Mind Works in Lifelines, and that's perfectly true-I did write about it in The Making of Memory, andLifelines has a different task. I'm going to try and interweave these two. And again, let me pause for a moment also to say what I'm doing. Steve makes in his book, and he made at the end of what he had to say there, what I can only describe as a personal political attack concerning the implications of some of the things that I've written about.

I do feel very strongly about issues of what I've called neuro-genetic determinism, and the political and social implications of some of the ideas that are floating around within genetics at the moment. It wasn't intention to discuss them this evening. I'm going to try not to be riled by what he said, but to put it slightly to one side. I am here essentially as a practicing biologist. I'm here for the same reasons I wrote Lifelines. I've spent my research life studying real living animals, and the workings of their brains, and worrying about the relevance of what I've observed to my own lived human experience. And like other biologists, I find the rather abstract theorizing of those who spend more time with their computers than with living organisms a bit distressing.

So my case is rooted in understanding how real brains and living processes in general work. I'm going to focus on Steve's main theses and show how Lifeline's approach gives us a very different understanding of them. Steve defines mind-he did it now and he did it before, as the information-processing property of the brain. The mind he talks about isn't a coherent unity; it's an interacting community of distinct modules, each specialized for a particular function. It's evolved, as he explained to us, as a device for enhancing human survival, and reproductive success, according to ultra-Darwinian principles. Now as Susan said at the beginning, no biologist is going to have any problems with the claims that we humans-all of our attributes, behavioral as well as physical have evolved, and they've been honed to their present form, at least in good part, by the workings of natural selection. The devil as usual is in the details. Steve, like me, quotes the evolutionary biologist, Theodesius Dobzhansky - "Nothing in biology makes sense except in the light of evolution".

I have a crucial emendation: "Nothing in biology makes sense except in the light of history." That is, evolutionary history, developmental history, social history, the history of our science itself. It was the last clause there that he took particular exception to; I'm not going to try and defend it this evening, I've got other tasks in mind. If he wishes to discount the evidence of philosophers, sociologists and economists who've studied scientific processes over the last 20 or 30 years he's at liberty to do so, but I suspect he's talking outside his terrain of knowledge.

Let me deal however with the little matter of mind. Steve's mind is a machine, a sort of abstraction that computer engineers program when exploring artificial intelligence. The megaphone diplomacy of the dust jacket of his book proclaims, "this is the best book ever written on the human mind." This is, I think, the vulgar dismissal of several thousand years of human science and philosophy. His mind, like a computer, deals with information. By contrast-and this is what I want to emphasize-real brains transform dead information into living meaning-the making sense of the world around us. It's a meaning which is given to sensory inputs by the working of the brain. It's based on experience, and it's provided through its evolutionary and developmental history. Let me give you an example, from Steve's own book. A footprint, he says, carries information. But the information, without an observer to give that information meaning, is strictly dead. Think for example of Robinson Crusoe on his island; finding a footprint on the sandy shore, the multiple meanings he gives that particular footprint- fear, anxiety, excitement, interpretation based on human history, and so on. Culture, history, personal experience-they all feed into that meaning.

Which brings me to another crucial point, that I emphasize again and again in Lifelines-that is finding the right level of explanation for any phenomenon, the fundamental point of scientific method-and here I mean not just natural science, but all science. Steve's agenda is grandiose, taking on in his last chapter the meaning of life, but his answer is I think slightly less relevant than 42. Take human love, for example-Steven explains love, and he did so again on Start the Week-as resulting from the shared interest of partners in the genes of their offspring. No possibility here for homosexual, same-sex love, no possibility here for the love which goes between-for people who are not-and infants who are not one's own genetic offspring, and so on. It's just this impoverishment of thought, which occurs again and again in the ways in which these terms are used, by people of Steve's persuasion in this context, that I find, both as a human and as a biologist, distinctly troublesome. Sure, as a neuro-scientist I can talk about the firing of cells in the hypothalamus; hormone surges, cortical representations, all the things that go on in the brain when one's in love. Neither those, nor the genes, tell us anything about the feeling of what it's like to be in love-what it means to be a person in love, two people in love, and their interactions.

The fact is that Steve's mind isn't a unified, coherent center of conscious thought, or emotion, or action-it's not a product of the inextricable interplay of biology and culture. It's a sort of Swiss army knife-it's modular. It's his analogy, not mine-it's a compressed miracle of pull-out devices-if not for taking stones from horses' hooves, then for seeing stereoscopically, or speaking grammatically. As Jerry Fodor points out, in the current issue of the London Review of Books-and it's surprising, because Jerry ought to have been one of Steve's heroes-nothing in this assemblage of independent modules enables us to understand what it means to be a person, with a conscious RIS. Neither cognitive neuroscience, Steve's area, or mine, neurobiology, can yet begin to approach that sort of problem. Each module, he argues, is evolved separately, and operates autonomously, although in the interests of the genes that created it. The modules spring fully formed, and unmediated from their genes, each presumably containing a miniature blueprint for a particular implement within the Swiss army knife. And here we come to the core of the argument, which Steve takes over holus-bolus from Richard Dawkins. For all the various complex aspects of being an organism, being a person, are merely ways in which our selfish genes program the lumbering robots which constitute us, to serve their, that is the genes', interest. This is precisely the view which Lifeline opposes. Just as Steve's mind has little to do with real brains, his genes have little to do with real strands of DNA, this is what I work with in the lab-they're theoretical entities. Real humans, like all other living organisms, grow and develop. They create themselves through the dynamic interplay of DNA and the cellular orchestra in which it's embedded, and the cells, with their external environment. Modularity, if it exists, emerges dynamically. Now I want to insist, despite what he said, that living organisms exist in four dimensions-three of space and one of time-and they can't be read off from the single dimension of DNA. Organisms and minds aren't empty phenotypes related one to one, with particular patterns of genes. Our lives form a developmental trajectory, or lifeline, and are stabilized by the operation of what I call homeodynamics-they're principles I discuss in the book. This trajectory isn't determined by our genes, nor is it partitioned into neatly dichotomous categories called nature and nurture. Rather, it's what I call an autopoetic process-he doesn't like the term- it's shaped, I say, by the interplay of specificity and plasticity. Insofar as any aspect of life can be said to be in the genes, our genes provide the capacity for specificity, a lifeline relatively impervious to developmental and environmental buffering; and also plasticity, the ability to respond appropriately to unpredictable environmental contingencies; that is, to experience. The crucial thing is this. All living organisms have simultaneously both to be and to become. Take a newborn baby, for example. The baby is born with a sucking reflex. A little while later, the baby develops into a child which doesn't suckle, it chews its food. Chewing involves a totally different set of muscles and operations than suckling. To develop, the newborn baby has both to be competent as a suckler, and to transform itself into a chewer. And it's that dynamic, that self-construction, which is completely lost in the abstract understanding of genes and the behaviors they control. And what I fear is that the reductionist and simplistic approach which Steve has offered us freezes life. In attempting to capture its being it loses becoming. It turns process into reified objects. Organisms are open systems-they're far from dynamic equilibrium. Continuity is provided by a constant flow of energy through them. Every molecule, every organelle, every cell, is in a constant state of flux. Formation, transformation, renewal. Dynamic stability of form persists, though every constituent of that form, every molecule, has been replaced. And the stability depends on the capacity of complex interacting systems to self-organize. In this view of living systems, there are no master molecules, no naked replicators controlling cellular events within the screened-off tranquillity of a nuclear board room. Genes, lengths of DNA, are engaged in a continual metabolic interchange with other cellular components. A molecular democracy constrained by cellular organization, and the needs of the organism.

And now finally I come to the question of evolution, and above all evolutionary psychology, and Steve's famous simplistic reverse engineering, by which we're to understand How the Mind Works. The trouble with reverse engineering the mind, is that by contrast with human artifacts, when we're told the story about how it might have arisen, we've simply no way of testing it out. Evolutionary stories, almost by definition just-so stories of the sort Rudyard Kipling provided when he explained how the elephant got its trunk-I'm quite sure that we could find an evolutionary explanation why so many of the men writing in this area are called either Steve or Richard. It doesn't actually, however, help us forward at all. Now although Steve Pinker is aware of the fallacy of assuming that every biological feature is adaptively designed, through infinitely flexible and all-wise natural selection, he frequently ignores his own caveats. Thus at one point he discusses the tortuous route that the human seminal ducts take from the testes up through the body and across the ureter to the penis, and explains this on the well-known but Kiplingesque grounds that "the testes of our reptilian ancestors were inside their bodies. The bodies of mammals are too hot for the production of sperm, so the testes gradually descended into a scrotum." If Superman is so clever, why does he wear his underpants outside his trousers? Natural selection, if so clever, why don't they evolve sperm which can survive at higher temperatures, rather than the ungainly and hazardous physical control system that was adopted? Almost certainly it's either because of contingency, the chance events that another Steve, Steve Gould, evoked in his rich account of evolutionary process in his book Wonderful Life, or because there are other design constraints on what can or cannot be achieved by natural selection. That is, natural selection doesn't work unrestrictedly, a la carte, but is limited to a table d'hote choice of only a limited range of options. We don't have to find adaptations for everything. Again, the alternative viewpoints in Lifelines: organisms are in constant interaction with their environments. Organisms actively select and transform their environments, just as environments select and transform organisms. I don't just mean humans, I mean any living system. Even a single-celled organism chooses, changes, transforms its environment in particular ways. Evolutionary change occurs as a result of the continued interception of lifeline trajectories with changing environments. Such change occurs at multiple-levels, from the molecular to the species. That is, the individual gene, selfish or not, is not the only site of evolutionary change. Natural selection is the prime, but not the only mechanism of this change. There are constraints on selective processes. Not all change is adaptive, as Steve has agreed. Some may be contingent, accidental, accidents of history and essentially neutral in its effect. And because of the extent to which organisms select and modify environments, they're not simply the passive victims of selective processes, but play an active part in their-in our-own destiny.

Third, evolution isn't indefinitely flexible. Not all that's possible is achievable. This is partly because living processes are in their essence only comprehensible in historical context, and there are no such things in life as de novo engineering solutions to problems. The material for evolutionary change is restricted to what's currently present. Opening certain pathways closes others. Further, there are physical and chemical constraints on the structural possibilities available through evolution, >from the rates of diffusion of dissolved gases, to the mechanical properties of the calcium phosphate of bones, or the cellulose walls of plant cells. These limit cell size, body volumes, rates of movements, patterns of behavior, and they can't be bypassed by any amount of genetic tinkering. Let's be clear: humans can't be turned into angels by grafting onto us a genetic program for wings; it's nothing to do with virtue, but because no wing bone and muscle structure could achieve the lift to enable us to fly. What we do possess, courtesy of our evolutionary history, is the cerebral, social and technical facilities for every single one of us to construct societies and machines, enabling all of us to fly, without the need for genetic change at all. Is this dynamic which is so lacking from what used to be called sociobiology and is now called evolutionary psychology, to which Steve has become such an enthusiastic convert. He argues his mind modules evolved to suit humanity's Stone Age existence, to help our ancestors survive as social animals, by lying, swindling convincingly, but by being able to detect lying and swindling in our neighbors, by murdering our step-children but protecting our genetic kin. The Stone Age they portray has I always feel something of the Flintstone quality about it; that is current U.S. suburban mores transported into the dim past. Further, for reasons that are completely unclear to me, evolution of brains and behavior apparently stopped in the Stone Age, though elsewhere Steve points out quite rightly the time that's elapsed since then would be quite adequate for quite dramatic brain changes. The point is that once we accept that the key to understanding living processes isn't just evolution but history, and abandon the extraordinarily static world-view of ultra-Darwinism, then all this romanticized Stone Age nonsense falls into proper perspective. It's surely precisely the unique properties of human biology that have enabled us to evolve the minds and societies that we inhabit today. But in evolving these societies our minds and brains too have been profoundly changed.

Let me give one last biological example. The human cerebral cortex has evolved from structures which in our reptilian ancestors were used for odor detection. On the Pinker model of the world, this would mean that we think by smelling. We don't. Old structures develop new functions as part of the lifeline trajectories of individuals, societies, and species.

Now finally, what I find very odd about all this macho evolutionary talk, with its wild speculative finale on the meaning of life, is the extent to which in the last analysis it wants to have its cake and eat it. We are, evolutionary psychology argues, mainly the deterministically driven products of our selfish genes and their sole interest, that of replication. All our deepest desires and emotions, our abject selfish failures, as well as our most selfless ambitions to create a more beautiful world, these are all simply shadow-play. Yet at times Steve, quite rightly, like Richard Dawkins and others, recoils from this bleak vision. He is in some unexplained way free; as he puts it, very clearly, in the book, if his genes don't like what he does, they can go jump in the lake. Now, what I find very puzzling is to understand where this freedom comes from. Does it fall from the sky? Are we suddenly to invoke some new deity to enable him to escape from the deterministic trap into which he's painted himself? I simply can't go with this Cartesian split. This is why I want to claim that I'm talking a deeper and a richer materialism than Steve is in his account. It's a materialism that takes account of dynamism, and isn't statically frozen into the past. And it's this richer understanding of biology, the mechanistically driven approach, which helps us to understand that for us, like all living creatures, the future is radically unpredictable. And this is the take-home message, not any of the political overtones or undertones which Steve has chosen to read into it, which is inLifelines. I have written political books, or books which have attempted to discuss politics; Lifelines doesn't. It's an attempt to discuss biological processes. An attempt to help us understand how we need to take on board the reductionist triumphs of biology of the last century, which he has so eloquently described; but also recognize that in order to understand living processes in their depth and richness, these triumphs of genetics, of biochemistry, of the study of human behavior of the last decades, need to be set into a much richer and deeper context. It's that context which I insist the new biology ought to be about. And what it implies above all, so far as humans are concerned, is that we have the ability to construct our own futures, though in circumstances not of our own choosing. This ability is provided by our genes as part of the living dynamic processes in which they are embedded. And in the final words of Lifelines, it is therefore our biology which makes us free. Thank you.

PINKER: Many points that Professor Rose has made puzzle me, because I don't understand what they have to do with any of the theses of evolutionary psychology orHow the Mind Works. The claims that "we're not infinitely flexible," that there are no "empty organisms," that organisms are "open systems organized in four dimensions," "self-organizing," "are not just naked replicators," "actively select their options," "interact with their environment," "should be understood at multiple levels," "are dynamic," are "not passive victims," "are not indefinitely flexible," and so on-all these are points that I completely agree with, and I don't understand what the point of Professor Rose's argument is.

Let me concentrate, then, on more substantive points. Number One: Our own ability to defeat the metaphorical designs of our genes, such as choosing to remain childless, has nothing to do with Cartesian dualism, and I explain in How the Mind Works where they do come from. The mind is composed of many parts. One part is sexual desire; another part is an ability to apply cause and effect reasoning to the world. In the world we live in now, we have available to us contraception, which was not available in the world in which we evolved. One part of the mind, the part that figures out that one can have the pleasures of sex without necessarily having children, can be applied today in a way that would not have been possible as we evolved. That's a purely mechanistic, non-Cartesian explanation.

Second, about reverse engineering. It is NOT the empty exercise that Professor Rose hinted at. As Ernst Mayr, someone that Professor Rose quotes approvingly, points out, if it were not for the adaptationist program, or reverse engineering, we would still be ignorant about what most of the parts of the body do, such as the spleen. The science of physiology was born when Harvey reverse-engineered the circulatory system by noticing that there are valves in the vein and that they must be there to help the blood circulate.

In the case of psychology, the reverse engineering can work if one does it in two steps. First, do the psychology that characterizes the properties of an aspect of the human mind. Second, have an INDEPENDENT optimality analysis of the domain in question that could characterize-completely independently of our study of the mind-what the optimal solution to an adaptive problem would be under the constraints available. That can come from optics in the case of vision; from dynamics and kinematics, in the case of motor control; from the theory of computational systems, in the case of memory, and so on. It's the degree of fit between the independent optimality analysis and the empirical facts of the mind that break the circle and make reverse-engineering something other than just-so story telling.

Number Three: Professor Rose ridicules my allusions to life in the Stone Age. In fact it is not a fantasy of a Flintstones way of life, but simply points out obvious historical facts-and Professor Rose rightly emphasizes the importance of history-such as that many of the features of life today that we take for granted had a recent historical origin and could not have been part of the environment in which we evolved, such as written language, contraception, police, court systems, formal education and, so on. One can come up with surprising hypotheses based on these minimal and noncontroversial assumptions about the difference between the world that we live in now and the world in which we evolved.

Fourth, it is not true that I suggested that the only form of love is love of spouses, which I suggested was a way of cherishing the other person who has as much at stake in one's children as one does oneself. I also talk about long-term companionate love, as would be found in a pair of close friends, and about the love of family. He refers to our ability to love non-biological offspring; well, there is an empirical prediction that the love of biological offspring is not the same as love of non-biological offspring, and Martin Daly and Margo Wilson have done an extensive set of studies showing that indeed those two forms of love are not the same. Their analysis of the different patterns of love and abuse of biological children versus step-children bears out the hypothesis that those are different kinds of love. But I have to stop now.

ROSE: Let me just pick up a couple of points in Steve's response. He says that our ability has nothing to do with Cartesian dualism. He it is who wrote that if the genes don't like what he does they can go jump in the lake. I didn't say that. He wrote it. Now where did these different parts of the mind that he's talking about and which conflict with one another come from if they're not generated as the result of interaction between genes, the cells and the environment during the wiring or development of the brain? Materialism has to insist that our genes have to do with everything; they have to do with both, if you like the genetic urge to reproduce that he described, and the desire to have sex without reproducing that he described as the advantage of contraception. That's where materialism comes in, and that's where my challenge to him of being a Cartesian endures, because it's precisely where he wants to let the mind, or these different bits of the mind float free, that I won't accept.

Now we come to the issue of reverse engineering. He's quite wrong when he says that physiology was studied by reverse engineering; when William Harvey likened the pumping-the workings of the heart-to the workings of a pump, this wasn't reverse engineering, he was drawing a metaphor as to how you could understand the mathematics of heart function. It was a tremendously revealing and important metaphor. The problem we have in science, particularly in biology, is to distinguish between metaphor, like that, which gives you mechanical properties; analogy, when we say that a brain is like a computer, which can be very misleading in a variety of ways on which both he and I would agree; and strict homology, when we say that a process is evolutionarily developed and depends on mechanisms that are identical in our reptilian ancestors and ourselves,. The mistake that evolutionary psychology makes in this reverse engineering discussion is constantly to mistake metaphor and analogy for homology, and draw what I regard as both horrendous scientific and horrendous political conclusions from it. Finally, love-oh dear, that really won't do, Steve, you were the person again on Start the Week who explained love in terms of shared the genetic interest that you and your partner had in the rearing of offspring. You were indeed challenged on Start the Week about why you yourself chose to remain childless, and I think you handled that perfectly appropriately. But what I'm trying to insist is that the term love cannot be reduced simply to that shared genetic interest. It cannot I think even be sensibly argued to have arisen homologously as a result of evolutionary processes which indeed produce a shared genetic interest in all of us in our offspring. Human life, human society, is much much richer than these travesties. And I do insist that what you offer is a Flintstone type travesty of life today. I really won't buy the Daly and Wilson argument about infanticide. I suspect that there is a wealth of criminological knowledge which sort of makes much better sense than this one study that you and your evolutionary psychology colleagues constantly quote in order to boost this particular argument.