Saturday, November 05, 2005

Stabbing repeatedly, with a purpose.

Is science driven by inspired guesswork?

(Filed: 01/11/2005)

History abounds with examples of how instinct, not data, led to discoveries. Even Einstein's theory of relativity had to wait decades for verification, says Ian McEwan

Proof, whether in science or daily life, is an elastic concept, interestingly beset with all kinds of human weakness, as well as ingenuity.

For centuries, brilliant Christian scholars demonstrated by rational argument the existence of a sky-god, even while they knew they could permit themselves no other conclusion.

When Penelope is uncertain whether the shaggy stranger who turns up in Ithaca really is her husband Ulysses, she devises a proof invoking the construction of their nuptial bed, which would satisfy most of us, but not many logicians.

The mother wrongly jailed for the murder of her children, on the expert evidence of a pediatrician, reasonably questions the faith of the courts in scientific proof concerning sudden infant death syndrome.

And the precocious 10-year-old mathematician who exults in the proof that the angles of a triangle always add up to 180 degrees will discover before his first shave that in other mathematical schemes this is not always so.

Very few of us know how to demonstrate that two plus two equals four in all circumstances. But we hold it to be true, unless we are unlucky enough to live under a political dispensation that requires us to believe the impossible; George Orwell in fiction, as well as Stalin, Mao, Pol Pot and various others in fact, have shown us how the answer can be five.

It has been surprisingly difficult to establish definitively what the truth is about any matter, however simple. It is always hard to get a grasp of one's own innate assumptions, and it was once perilous to challenge the wisdom of the elders, or the traditions that had survived the centuries, and dangerous to incur the anger of the gods, or at least, of their earthly representatives.

Perhaps it was the greatest invention of all, greater than that of the wheel or agriculture, this slow elaboration of a thought system, science, that has disproof at its heart and self correction as its essential procedure.

Only recently, over this past half millennium, has some significant part of humankind begun to dispense with the kinds of insights supposedly revealed by supernatural entities, and to support instead a vast and disparate mental enterprise that works by accretion, dispute, refinement and occasional radical challenges.

There are no sacred texts - in fact, a form of blasphemy has turned out to be useful. Empirical observation and proof are, of course, vitally important, but some science is little more than accurate description and classification; some ideas take hold, not because they are proved, but because they are consonant with what is known already across different fields of study, or because they turn out to predict or retrodict phenomena efficiently, or because persuasive persons with powers of patronage hold them - naturally, human frailty is well represented in science.

But the ambition of juniors and an adversarial method, as well as mortality itself are mighty enforcers. As one commentator has noted, science proceeds by funerals.

And again, some science appears true because it is elegant - it is economically formulated, while seeming to explain a great deal. Despite fulmination against it from the pulpit, Darwin's theory of natural selection gained rapid acceptance, at least by the standards of Victorian intellectual life.

His proof was really an overwhelming set of examples, laid out with exacting care. A relatively simple idea made sense across a huge variety of cases and circumstances, a fact not lost on an army of Anglican vicars in country livings, who devoted their copious free time to natural history.

Einstein's novel description, in his theory of general relativity, of gravitation as a consequence, not of the attraction between bodies according to their mass, but of the curvature of space-time generated by matter and energy, was enshrined in text books within a few years of its formulation.

Steven Weinberg describes how, from 1919 onwards, various expeditions by astronomers set out to test the theory by measuring the deflection of starlight by the sun during an eclipse. Not until the availability of radio telescopy in the early Fifties were the measurements accurate enough to provide verification.

For 40 years, despite a paucity of evidence, the theory was generally accepted because, in Weinberg's phrase, it was "compellingly beautiful".

Much has been written about the imagination in science, of wild hunches born out, of sudden intuitive connections, and benign promptings from mundane events (let no one forget the structure of benzene and Kekulé's dream of a snake eating its tail) and of the occasional triumph of beauty over truth.

In James Watson's account, when Rosalind Franklin stood before the final model of the DNA molecule, she "accepted the fact that the structure was too pretty not to be true".

Nevertheless, the idea still holds firm among us laypeople that scientists do not believe what they cannot prove. At the very least, we demand of them higher standards of evidence than we expect from literary critics, journalists or priests.

No wonder so much interest has been generated by the scientists who have responded to the question: "What do you believe is true even though you cannot prove it?" posed by John Brockman, a New Yorkbased literary agent and publisher of The Edge website.

There appears to be a paradox here: those who stake their intellectual credibility on rigorous proof are lining up to declare their various unfalsifiable beliefs. Should not scepticism be the kissing cousin of science?

Those very men and women who castigated us for our insistence on some cloudy notion that was not subject to the holy trinity of blind, controlled and randomised testing, are at last bending the knee to declare their faith.

The paradox, however, is false. As the Nobel laureate Leon Lederman writes in his reply: "To believe something while knowing it cannot be proved (yet) is the essence of physics."

This collection, mostly written by working scientists, does not represent the antithesis of science. These are not simply the unbuttoned musings of professionals on their day off. The contributions, ranging across many disparate fields, express the spirit of a scientific consciousness at its best - informed guesswork that is open-minded, free-ranging, intellectually playful.

Many replies offer versions of the future in various fields of study. Those readers educated in the humanities, accustomed to the pessimism that is generally supposed to be the mark of a true intellectual, will be struck by the optimistic tone. Some, like the psychologist Martin Seligman, believe we are not rotten to the core. Others even seem to think that the human lot could improve.

Generally evident is an unadorned pleasure in curiosity, a collective expression of wonder at the living and inanimate world which does not have an obvious equivalent in, say, cultural studies. In the arts, perhaps lyric poetry would be a kind of happy parallel.

Another interesting feature is the prevalence here of what E.O. Wilson calls "consilience". The boundaries between different specialised subjects begin to break down when scientists find they need to draw on insights or procedures in fields of study adjacent or useful to their own.

The old Enlightenment dream of a unified body of knowledge comes a little closer when biologists and economists draw on each other's concepts; neuro-scientists need mathematicians, molecular biologists stray into the poorly defended territories of chemists and physicists. Even cosmologists have drawn on evolutionary theory. And everyone, of course, needs sophisticated computing.

To address each other across their disciplines, scientists have had to abandon their specialised vocabularies and adopt a lingua franca - common English. The accidental beneficiary, of course, has been the layman who needs no acquaintance with arcane jargon to follow the exchanges. They are part of an ongoing and thrilling colloquium that is open to all.

©2005. Extracted from Ian McEwan's introduction to What We Believe But Cannot Prove: Today's Leading Thinkers on Science in the Age of Certainty, edited by John Brockman (Free Press), available for £9.99 plus 99p p&p. To order please call Telegraph Books on 0870 428 4112. Ian McEwan's latest novel, Saturday (Jonathan Cape), is also available for £15.99 (rrp £17.99) plus £1.25 p&p.

Thinkers' beliefs

Great minds can sometimes guess the truth, before they have marshalled the evidence or the arguments, using what Diderot called the "esprit de divination".

John Brockman asked scientists, futurists and other creative thinkers: "What do you believe is true even though you cannot prove it?"

Randolph Nesse, University of Michigan: "I'm pretty sure that people gain a selective advantage from believing in things they can't prove. Those who are occasionally consumed by false beliefs do better in life than those who insist on evidence before they believe and act."

Stanislas Dehaene, Institut National de la Santé, Paris: "We vastly underestimate the differences that set the human brain apart from the brains of other primates.''

Carlo Rovelli, Centre de Physique Théorique, Marseille: "Time does not exist."

Seth Lloyd, Massachusetts Institute of Technology: "I believe in science. Unlike mathematical theorems, scientific results can't be proved. They can only be tested again and again, until only a fool would refuse to believe in them."

Daniel Hillis, chairman, Applied Minds Inc: "I know that it sounds corny, but I believe that people are getting better. In other words, I believe in moral progress."

Craig Venter, president, J Craig Venter Science Foundation: "Life is ubiquitous in the universe."

Janna Levin, Columbia University: "I believe that there is an external reality, and you are not all figments of my imagination."

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