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|October 23, 2009, 6:37 pm |
Letters: Scientists Respond to Our Review of Richard Dawkins’s ‘Greatest Show on Earth’
By Elsa Dixler
The review by Nicholas Wade, a science reporter for The Times, of Richard Dawkins’s “Greatest Show on Earth: The Evidence for Evolution” (Oct. 11) drew an unusually large number of letters to the editor. And an unusually large number of those came from readers who identified themselves as scientists or philosophers. Because we had room for just two responses on the letters page of the issue of Oct. 25, we thought it only fair to our credentialed correspondents to present their comments here. —Elsa Dixler
The offending article:
|By NICHOLAS WADE|
Published: October 8, 2009
The theory of evolution really does explain everything in biology. The phenomena that Darwin understood in broad brush strokes can now be accounted for in the precise language of DNA. And though biological systems have attained extraordinary levels of complexity over the passage of time, no serious biologist doubts that evolutionary explanations exist or will be found for every jot and tittle in the grand script.
THE GREATEST SHOW ON EARTH
The Evidence for Evolution
By Richard Dawkins
470 pp. Free Press. $30
Richard Dawkins’s Web SiteTo biologists and others, it is a source of amazement and embarrassment that many Americans repudiate Darwin’s theory and that some even espouse countertheories like creationism or intelligent design. How can such willful ignorance thrive in today’s seas of knowledge? In the hope of diminishing such obscurantism, the prolific English biology writer Richard Dawkins has devoted his latest book to demonstrating the explanatory power of evolutionary ideas while hammering the creationists at every turn.
Dawkins invites the reader to share the frustration of an imaginary history teacher, some of whose students refuse to accept that the Roman Empire ever existed, or that Latin is the mother tongue from which the Romance languages evolved. Instead of concentrating on how Western culture emerged from the institutions of the Roman state, the teacher must spend time combating a school board that insists he give equal time to their alternative view that French has been spoken from time immemorial and that Caesar never came or saw or conquered. This is exactly analogous to the plight of the biology teacher trying to acquaint students with the richness of modern biology in states where fundamentalist opponents of evolution hold sway.
Dawkins has a nice sense of irony, deployed without mercy on the opponents of evolution. If the creationists think the earth is less than 10,000 years old, rather than 4.6 billion, he asks, shouldn’t they assume, by the same measure, that North America is less than 10 yards wide? The book is even more enjoyable when Dawkins forgets the creationists and launches into evolutionary explanations, whether of the hippopotamus’s long-lost cousin the whale, or of the long-tongued moth that Darwin predicted must exist to pollinate a Madagascan orchid with a nectary 11 inches in length. He gives striking examples of “unintelligent design,” forced on evolution because it cannot ever start from scratch but must develop new structures from older ones.
He describes a beautiful thought experiment to demonstrate a rabbit’s cousinship to a leopard. Imagine a chain of rabbit generations, daughter-mother-grandmother, stretching back into evolutionary time. The creatures become less and less rabbitlike until one reaches the early mammalian species from which both rabbits and leopards evolved. Now do a hairpin bend and follow the generations forward in time down the lineage that leads to leopards. The trunk and branches are long gone, but all living species are the twigs of a single tree.
There is one point on which I believe Dawkins gets tripped up by his zeal. To refute the creationists, who like to dismiss evolution as “just a theory,” he keeps insisting that evolution is an undeniable fact. A moment’s reflection reveals the problem: We don’t speak of Darwin’s fact of evolution. So is evolution a fact or a theory? On this question Dawkins, to use an English expression, gets his knickers in a twist.
Evolutionary theory is a mansion that has been under vigorous construction for the last 150 years and is still far from complete. A ballroom-size controversy is whether natural selection can operate at the level of groups as well as that of individuals. The evolutionary theory of aging, which predicts that many genes must be involved in determining life span, recently collapsed when researchers found that the lifetimes of laboratory organisms can be tripled or better by changing a single gene. If the theory of evolution is still in full flux — as befits any scientific theory at the forefront of research — how can evolution be said to be a fact?
Dawkins is aware that evolution is commonly called a theory but deems “theory” too wishy-washy a term because it connotes the idea of hypothesis. Evolution, in Dawkins’s view, is a concept as bulletproof as a mathematical theorem, even though it can’t be proved by rigorous logical proofs. He seems to have little appreciation for the cognitive structure of science. Philosophers of science, who are the arbiters of such issues, say science consists largely of facts, laws and theories. The facts are the facts, the laws summarize the regularities in the facts, and the theories explain the laws. Evolution can fall into only one of these categories, and it’s a theory.
Other systems of thought, like religion, are founded on immutable dogma, whereas science changes to accommodate new knowledge. So what part of science is it that changes during intellectual revolutions? Not the facts, one hopes, or the laws. It’s the highest-level elements in the cognitive structure — the theories — that are sacrificed when fundamental change is needed. Ptolemaic theory yielded when astronomers found that Copernicus’s better explained the observations; Newton’s theory of gravitation turned out to be a special case of Einstein’s.
Richard Dawkins’s Web SiteIf a theory by nature is liable to change, it cannot be considered absolutely true. A theory, however strongly you believe in it, inherently holds a small question mark. The minute you erase the question mark, you’ve got yourself a dogma.
Since the theory of evolution explains and is in turn supported by all the known facts of biology, it can be regarded as seriously robust. There’s no present reason to think it has any flaws. But when we learn how life evolved on other planets, evolution could turn out to be a special case of some more general theory.
When Dawkins asserts that evolution “is a fact in the same sense as it is a fact that Paris is in the Northern Hemisphere,” it seems he doesn’t know what a theory is. Yet he is justified in his passion to demonstrate how beautifully the theory of evolution explains the biological world. How can his knickers be untwisted?
The best way, in my view, is to distinguish between evolution as history and evolution as science. Evolution is indeed a historical fact. Every living thing and every fossil-bearing rock bears evidence that evolution occurred. But evolution is not a scientific fact as philosophers of science see it. In science it plays a far grander role: it is the theory without which nothing in biology makes sense. The condition of this high status is that it cannot be the final and absolute truth that Dawkins imagines it to be; it is liable to future modification and change like any other scientific theory.
This brings me to the intellectual flaw, or maybe it’s a fault just of tone, in Dawkins’s otherwise eloquent paean to evolution: he has let himself slip into being as dogmatic as his opponents. He has become the Savonarola of science, condemning the doubters of evolution as “history-deniers” who are “worse than ignorant” and “deluded to the point of perversity.” This is not the language of science, or civility. Creationists insist evolution is only a theory, Dawkins that it’s only a fact. Neither claim is correct