Saturday, June 30, 2007

Dawkins and Miller Review Behe's Book

The latest reviews of Michael Behe's new book, The Edge of Evolution, are by Kenneth Miller, in Nature (June 28), and Richard Dawkins, in The New York Times Book Review (July 1). Although both Miller and Dawkins make some good points, neither one is intellectually rigorous, because their animosity towards Behe leads them to make evasive or even dishonest claims.

Like many critics of "intelligent design theory" (myself included), Dawkins criticizes ID for relying on negative rather than positive arguments. ID proponents challenge Darwinian scientists to present step-by-step evolutionary explanations for complex living mechanisms. Then, whenever there is some difficulty in laying out such precise explanations, the ID proponents declare that this confirms the truth of intelligent design, even though they have not themselves offered any positive explanation of the step-by-step process by which the Intelligent Designer created these living mechanisms.

But then the rest of Dawkins' review is weak. For example, he quotes the statement from Behe's biology department at Lehigh University declaring that "it is our collective position that intelligent design has no basis in science, has not been tested experimentally and should not be regarded as scientific." It's an interesting point that Behe has failed to persuade anyone in his own department to accept his claims. But I don't see how this allows us to dismiss his position without looking at his arguments and evidence for ourselves.

Dawkins goes on to ridicule Behe's argument that random mutation puts severe limits on Darwinian evolution, and Dawkins does this by using the example of how powerful artificial selection has been in breeding hundreds of different breeds of dogs, working upon the random mutational variety present in wolves. But Dawkins fails to acknowledge that Behe concedes that the evolution of species and varieties can be explained by Darwinian means--selection working on random mutation.

Miller, a biologist at Brown University, has been Behe's most persistent opponent. They have debated one another on many occasions. Miller's new review repeats his most common argument against Behe's claim that "irreducible complexity" cannot be explained by Darwinian means. Behe argues that in principle any irreducibly complex mechanism cannot by explained as a result of gradual Darwinian evolution, because any gradual process of assembly would fail since the absence of any one part would prevent the mechanism from functioning, and thus it would not be favored by natural selection. Miller--like most Darwinian biologists--responds to this by insisting that complex biological mechanisms can be assembled by natural selection working indirectly by combining simpler mechanisms that originally served some other function. This might apply, for example, to bacterial flagella--the little rotating tails that propel bacteria--because if we find certain structures within bacteria that have parts resembling the parts of the flagellar system, then we might consider the possibility that natural selection used parts originally adapted for one function to serve a new function within the flagellar system. But Miller and others fail to acknowledge that Behe explicitly recognizes this possibility of an indirect route of evolution through cooptation, so that older mechanisms serving one function might be put to use in newer mechanisms serving a different function. The problem, however, as Behe says, is that the Darwinians must explain step-by-step how such an indirect route could be likely. Behe's complaint is that Darwinians are good at spinning out speculative stories about how this might have occurred without exactly proving that this is really how it did occur. The research that Miller cites in his review suffers from this weakness--we have imaginative scenarios about how complex mechanisms might have evolved through a long, indirect route from simpler mechanisms, but there is no clear evidence that it really did happen this way.

Now, again, the problem is that as long as the Darwinians are put on the defensive and have to provide full step-by-step evolutionary pathways to complex structures, their explanations will often appear highly speculative and thus subject to doubt. But if the proponents of ID are put on the defensive and have to provide full step-by-step explanations of exactly when, where, and how the Intelligent Designer created these complex structures, then the ID position is exposed as resting on negative arguments with almost no positive content.

Miller is dishonest about one point in his review. He writes: "Apparently he has not followed recent studies exploring the evolution of hormone-receptor complexes by sequential mutations (Science 312, 97-101; 2006)." The article to which he refers offers an explanation of how the interaction between a hormone and its receptor could have evolved. When it was published last year, it was widely discussed as a possible refutation of Behe's argument about "irreducible complexity." Miller implies ("apparently he has not followed . . .") that Behe has not read this paper or has not responded to it. But as Miller must know, Behe and others responded to the paper last year on the Discovery Institute website. Behe's response can be found here. First of all, Behe suggests that this simple hormone-receptor interaction is not an example of an "irreducibly complex" system, and so he would see this as probably explainable in Darwinian terms. But he also raises some questions about the plausibility of the evolutionary scenario offered in the article. In any case, Miller leaves his reader with the assumption that Behe is completely ignorant of a widely discussed and publicized article refuting his theory.

Dawkins and Miller acknowledge only in passing what to me is the big story coming out of Behe's book--the extent to which he accepts Darwinian science and rejects Biblical creationism. Dawkins asks, "Do his creationist fans know that Behe accepts as 'trivial' the fact that we are African apes, cousins of monkeys, descended from fish?" Miller comments: "No doubt creationists who long for a scientific champion will overlook the parts of this deeply flawed book that might trouble them, including Behe's admission that 'common descent is true,' and that our species shares a common ancestor with the chimpanzee."

It's not so surprising, then, that one of the customer reviews of Behe's book on the website is entitled "Michael Behe Sells Out to Darwinism!"

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