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The Edge of Evolution: The Search for the Limits of Darwinism
By Michael Behe
Free Press, 2007 (also available in audio, paperback available in June)

Would an infinite number of Darwinians, working at for an indefinite period of time, eventually prove a single instance of evolution producing a new species?

Philip Kitcher, a philosopher of science and committed Darwinian, confesses in his book, Living with Darwin, that if Darwinians "were to try experimenting on the natural selection of organisms with relatively long generation times it would take the lives of thousands of successive investigators to provide even the slightest chance of even the first steps toward experimental success." Living with Darwin, it turns out, takes a lot more commitment than most people realize.

Materialists do not accept an afterlife, of course, but they do believe in an infinite amount of time, and they surmise that given enough time, anything — including life as we know it — can happen. (Thus, it is famously postulated, infinite monkeys at infinite keyboards could produce the complete works of Shakespeare.) This argument runs into an empirical wall with the big bang, which limits the amount of time for life to develop to about 15 billion years. It also has the theoretical problem that long stretches of time do not make impossibilities more possible. A lot of time does make improbabilities more probable, but multiplying time does not guarantee that long sequences of improbabilities will actually occur.

Biology certainly has a lot to say about the role of luck in the evolution of life, but the question of how much luck evolution needs and how much luck nature provides to get the ball of life rolling has been as much a matter of philosophical and mathematical speculation as empirical observation. Only in the past few decades has the state of genetic research reached the point where an informed judgment about the probabilities presupposed by Darwinism can be made. Michael Behe's latest book, The Edge of Evolution, should establish the precedent for future debates. Darwinists will appeal Behe's verdict, no doubt, but for readers with an open mind, it will be hard to overturn.

Darwinists are imaginative when it comes to speculating about the possible pathways that connect the stages of evolutionary development. Behe demonstrates how these theoretical constructions run into too many roadblocks in the real world of genetics. Rather than demolish Darwinism, however, Behe wants to explore its limits. He acknowledges that scientists can follow the lineage of all creatures back to a common ancestor. He also acknowledges that Darwinian theory can account for some aspects of the development of new species. He just doesn't think that random mutation and natural selection are an exhaustively complete description of the path life has taken.

Behe's previous book, Darwin's Black Box, argued that some cases of design in nature are too elegant to have been produced by chance. His critics attacked him on two fronts. First, they suspected that his talk of intelligent design was merely a ruse for getting God back into public education. In other words, they impugned his motives, which is always a sign of rhetorical desperation. Even if his motives are suspect, his arguments should be examined on their own terms. Moreover, Behe is not afraid to offend all parties of the evolution debate. He accepts the common ancestry of chimps and humans, and he thinks there is no theological problem in imagining God working through the secondary causes posited by Darwin. Behe's position is hardly designed for easy use in the culture wars.

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March (Web-only) 2008, Vol. 52

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