Tuesday, January 22, 2013

Survivor's Guilt; or Nature Thinks She's So Smart

(Grammar obsessive digression: I can't quite make up my mind whether the apostrophe in the title should be before the final s or after it -- singular or plural?)

But anyway, here's another meme that's going around, like the flu but slightly less virulent:

"Faith is the reorganization of observations so that they fit neatly into a particular belief system." Well, no, that's science: the fitting of observations into a particular belief system, aka theory. This is on my mind today because I'm reading Walter Alvarez' T. Rex and the Crater of Doom (Princeton, 1997).  (Also, a more technical point: observations have no meaning except as they are framed within a theory or other organizing framework. Facts don't speak for themselves. This isn't exactly rocket science, though a lot of scientists talk as though they didn't know it.)

T. Rex and the Crater of Doom is Alvarez' account of how he and many other scientists filled out a speculation with facts that, they concluded, validated and confirmed the speculation.  The speculation, which has become fairly well-known by now, was that the mass extinction which killed off the dinosaurs and many other species of animals and plants 65 million years ago, was caused by a large object, probably an asteroid, hitting the earth.  The mass extinction, formerly known as the Cretaceous-Tertiary Extinction (also KT, as Alvarez refers to it throughout the book) has been renamed The Cretaceous-Paleogene Extinction Event by Politically Correct zealots at the International Commission on Stratigraphy.  (The same kind of people who decided Pluto isn't a planet.)  There have been numerous mass extinctions, but KT is one of the best-known because of the public fascination with dinosaurs, but no one knew why they happened.

It's a fascinating story, and undermines the faith-science dichotomy in the meme above.  At the beginning Alvarez didn't have any evidence for believing that KT was caused by something big hitting the earth, he had a hunch.  Then he had to think of what could constitute evidence, then he had to look for it.  Occasionally he found what looked like disconfirming evidence, but he didn't lose faith: he kept digging and thinking until he found new facts or a way to think about the facts he had.  In the end he came up with a lot of evidence that confirmed his hunch, and I'm not denying that it's good evidence or that the KT extinction happened, or happened that way.  What I'm saying is that it shows that a simple science/faith dichotomy doesn't work.

The general acceptance of Alvarez' theory struck a blow against the uniformitarianism that had dominated geology for a couple of centuries, which again had been a matter of faith: scientists simply asserted that no catastrophes had any important effects on the earth.  The doggedness with which they clung to this belief is interesting.  There was nothing either illogical, let alone supernatural, about the idea of an asteroid or comet striking the earth, but it was resisted fiercely for a long time.  Not only that, but some scientists continued to reject Alvarez' theory long after most of their colleagues accepted it, arguing that his evidence didn't prove what he thought it did.  That's a reminder that rejecting a scientific theory is not in itself anti-science, which many scientists forget in times of controversy.

T. Rex and the Crater of Doom also quietly rejects the heroic fantasy of the solitary scientist battering away at Nature until she surrenders her secrets: from the beginning Alvarez worked with other scientists, and a worldwide network of colleagues contributed data and suggestions to help.

Scientists have to have faith in their theories, or they would abandon them at the first disconfirming evidence, and science would fail.  They also have faith in science itself, since science has as many embarrassing failures in its history as it has successes.  It's an old joke among historians and philosophers of science.  The scientific method is like a besieging army: if it fails to capture one city, it moves on to another that looks more vulnerable, in hopes of better success. Where faith comes in is the belief that eventually, every problem will be conquered.  Declaring that science will never be able to solve its unsolved problems is analogous to declaring that gods definitely don't exist.  It's notoriously hard to prove a negative, but asserting the positive requires faith.

There's one thing about Alvarez' presentation that bothers me, though: his personification of Nature.  This might be partly the all-too-common scientists' assumption that you have to dumb down a popular account to snow the rubes.  Mary Midgley wrote that when she "complained of this sort of thing to scientists, I have sometimes met a surprising defence, namely, that these remarks appear in the opening or closing chapters of books, and that everybody knows that what is found there is not to be taken literally; it is just flannel for the buying public" (Evolution as a Religion, Methuen, 1985, 67).  Whatever the reason, Alvarez writes of Nature as a conscious agent, even an adversary, throughout his book.  Some examples (there are any more):
As we struggled to understand what had happened, it almost seemed as if Nature had cleverly constructed a maze of alibis, misleading clues, and false trails [82].

As scientists, we are engaged in a conversation with Nature. We ask questions – like “Where is the crater?” – by making observations or performing experiments. And Nature answers, with the results of the observation or the experiment [85].

… to understand the real meaning of Nature’s answers, or how many ways there are to make mistakes and get fooled [86].
This last one reminded me of the immortal beginning of Robert Treese's 1973 paper on homosexuality and the Bible: "What is God trying to tell us about homosexuality?"  You'd think science was engaged in a game of charades.
But we had all been fooled!… How did Nature fool us? Only years later, after the Yucat√°n crater was finally found, did we come to understand how we had been misled? [94]

Nature misled us by mixing sedimentary rocks rich in calcium and magnesium together with the underlying continental crust, which was rich in silicon [95].

At last, it seemed, Nature’s trick had been figured out … It was satisfying to have finally understood Nature’s ploy, but the satisfaction was premature. Nature was about to have another laugh at our expense [105].
And so on, and on.  I remember a passage in Norbert Wiener's Cybernetics (1948) to the effect that the physical scientist has an advantage over the social scientist in that Nature doesn't cheat.  That's because Nature is not a person: Nature is an abstraction, though it has long been personified as an alternative to God, a way of avoiding theological reference in books while still anthropomorphizing the inanimate, impersonal world.  It seems to be very difficult to avoid personifying the impersonal, even for scientists, but that's supposed to be a major part of what science is supposed to be about.  But how flattering to cast oneself as one who outsmarted crafty, dissimulating Nature.  It's like beating Death at a game of chess, almost as good as stealing fire from the gods.