We all have hunches, beliefs we can barely explain, or even simply hopes or dreams that some might think of as crazy, or scoff at as irrational, or unproven. But that's just the point of hunches, isn't it? Sometimes we're even right. Diderot called the gift of those who guess the truth before being able to prove it the "esprit de divination".
Which is why the latest "grand question" posed by the publisher of the scientific website edge.org, John Brockman, to 120 scientists and thinkers, is so wonderful: "What do you believe is true even though you cannot prove it?"
The answers, which spill to 60,000 words and were published this week, provide a fascinating insight into conjecture - and the power of imagination. Even the empirically driven, it seems, have their own leaps of faith.
Many scientists and researchers believe in the unseen and the unknown - in true love, the power of a child's mind, in the existence of aliens.
Joseph LeDoux, a New York neuroscientist, said the question was easy: "I believe that animals have feelings and other states of consciousness, but neither I nor anyone else has been able to prove it." Alison Gopnik, a Berkeley psychologist, wrote: "I believe, but cannot prove, that babies and young children are actually more conscious, more vividly aware of their external world and internal life, than adults are."
The unproven belief of the Sydney physicist Paul Davies was that the universe is "teeming with life": "I make this sweeping claim because life has produced mind, and through mind beings who do not merely observe the universe, but have come to understand it through science, mathematics and reasoning. This is hardly an insignificant embellishment on the cosmic drama, but a stunning and unexpected bonus. Somehow life is able to link up with the basic workings of the cosmos, resonating with the hidden mathematical order that makes it tick. And that's a quirk too far for me."
My favourite answer came from David Buss, a psychologist from the University of Texas, who has spent two decades studying human mating. He has documented "phenomena ranging from what men and women desire in a mate to the most diabolical forms of sexual treachery". He has studied "mate poachers, obsessed stalkers, sexual predators and spouse murderers". But, he wrote, "Throughout this exploration of the dark dimensions of human mating, I've remained unwavering in my belief in true love.
"While love is common, true love is rare, and I believe that few people are fortunate enough to experience it. The roads of regular love are well travelled and their markers are well understood by many - the mesmerising attraction, the ideational obsession, the sexual afterglow, profound self-sacrifice and the desire to combine DNA. But true love takes its own course through uncharted territory. ... It's difficult to define, eludes modern measurement and seems scientifically woolly. But I know true love exists."
Curious, isn't it, that the most important things in life can elude the abacus, the microscope, the hard drive, emboldening and frustrating the empirically driven. But we know they exist.
In his introduction, Brockman wrote that the answers were "a commentary on how we are dealing with the idea of certainty". We are in an age of "searchculture", he wrote, where Google and other search engines are leading us towards both correct answers and a naive sense of certainty: "In the future, we will be able to answer the question, but will we be bright enough to ask it? This is an alternative path. It may be that it's OK not to be certain, but to have a hunch, and to perceive on that basis."
I'm not sure why that is such a comforting thought in January 2005, when we are stomaching a planet not just of terrorism, war and a wilting environment, but a tsunami that swallowed villages, islands and hearts whole. The world, both natural and man-made, seems brutal and nonsensical. It's hard to sustain belief in much (except, paradoxically, in that which sustains us) and this week - particularly since the thoughtless and ill-timed comments of Phillip Jensen, the Anglican Dean of Sydney, that "disasters of this world are part of God's warning that judgement is coming" - there has been chest-beating worldwide about how God could allow such devastation to occur, and how the deaths of 155,000 people can possibly make sense.
What is curious is how the incomprehensibility and uncertainty push people not away from, but towards, faith. And how many more have shadowed church doors since September 11, 2001, and Bali, and now the tsunami.
G.K. Chesterton once wrote that the difference between the poet and the mathematician was that the poet merely tried to get his head into the clouds while the mathematician tried to get the clouds into his head - and it was his head that split. A theology of conflict, which assumes to know the the mind of God, at a time of immense suffering, seems to me to be a split head.
All we can continue to do is defiantly believe - whether it is that animals have feelings, infants have souls, love can last forever, miracles occur, God is love. That the true expression of the face of God in the midst of horror is to stubbornly, and consistently, care for each other.