Last year, on the 150th anniversary of the publication of Origin of Species, Darwin's stock soared higher than Apple's. It's 2010—time for a market adjustment.

The philosopher Daniel Dennett once called the theory of evolution by natural selection "the single best idea anyone has ever had." I'm inclined to agree. But Darwinism sticks in the craw of some really smart people. I don't mean intelligent-designers (aka IDiots) and other religious ignorami but knowledgeable scientists and scholars.

Take, for example, the philosopher Jerry Fodor of Rutgers University and the cognitive scientist Massimo Piattelli-Palmarini of the University of Arizona in Tucson. In What Darwin Got Wrong (Farrar, Straus and Giroux, 2010), these self-described atheists argue that the theory of natural selection is "fatally flawed." Their book, which I reviewed for The Philadelphia Inquirer, is, well, fatally flawed. For example, they air familiar debates over how large a role contingency plays in evolution; whether natural selection operates primarily at the level of genes; why certain clusters of genes persist unchanged for eons. Fodor and Piattelli-Palmarini wrap up the discussion of each debate with the same kicker: natural selection must be wrong.

But saying debates over contingency, levels of selection and gene conservation disprove evolutionary theory is like saying debates over the formation of Saturn's rings disprove heliocentrism. If you're going to shoot the king, the old saying goes, you had better kill him. Fodor and Piattelli-Palmarini don't even wound Darwin. What Darwin Got Wrong nonetheless serves as a useful reminder of more coherent complaints about natural selection.

I lump Darwin's secular critics into two camps: Some, such as the left-leaning biologists Stephen Jay Gould and Richard Lewontin (who are cited by Fodor and Piattelli-Palmarini), fear the political implications of Darwinian theory. If we accept evolutionary explanations of human nature, they suggest, we may come to believe that many insidious modern "-isms"—unbridled capitalism, racism, sexism and militarism—were highly probable outcomes of evolution and thus not easily subject to change. Given how genetic theories have been employed in the past, these concerns have merit.

Other critics object to Darwinism for precisely the opposite reason. They fear that evolutionary theory, even when buttressed by modern genetics and molecular biology, does not make reality probable enough. Reality seems too precarious, too much a product of blind luck. No one has worked harder to solve the improbability problem than the biologist Richard Dawkins. Ironically, Dawkins has also revealed how deep and possibly intractable the problem is.

In Climbing Mount Improbable (W. W. Norton, 1997) Dawkins emphasizes that the vast majority of variants of a given species fail to propagate; there are many more ways to be a loser in the game of life than to be a success. Surely that is true of life as a whole. Of all the imaginable possible histories of life, what is the likelihood that it would persist for billions of years, long enough to produce toads, baboons and Glenn Beck?

Dawkins also notes that "nature, unlike humans with brains, has no foresight." Each individual organism pursues its short-term interests regardless of the long-term consequences for life as a whole or even for other members of the species. Given this fact, it is all too easy to imagine scenarios in which one species—a bacterium or virus, perhaps—runs amok and destroys all life on Earth.

If our past was improbable, our future might be as well. Recognizing this implication of evolutionary theory, some scientists have proposed alternative mechanisms to make life more robust. For example, biochemists such as Ilya Prigogine and Stuart Kauffman (cited by Fodor and Piattelli-Palmarini) have postulated "self-organization" forces that made the origin of life and its subsequent history highly probable.

Other theorists have proposed that natural selection may favor not just genes or individuals but populations, species, even entire ecosystems. The most extreme version of this group-selection concept is Gaia theory, which holds that all of life somehow conspires to ensure its continued survival. Self-organization and Gaia are flawed theories that have won few adherents, but that doesn't mean that the problem they address doesn't exist.

Early in his career, the philosopher Karl Popper (yes, cited by F and P-P) called evolution via natural selection "almost a tautology" and "not a testable scientific theory but a metaphysical research program." Attacked for these criticisms, Popper took them back. But when I interviewed him in 1992, he blurted out that he still found Darwin's theory dissatisfying. "One ought to look for alternatives!" Popper exclaimed, banging his kitchen table.

Is it possible that some future genius will discover an alternative that supplants Darwinism as our framework for understanding life? Will we ever look back on Darwin as brilliant but wrong?

Postscript: I'd like to thank my buddy Robert Hutchinson—author, editor, polymath, punster, triathlete—for suggesting that I call this blog "Cross-check". A cross-check is an illegal hit in hockey. I don't cross-check on the ice, but on this blog anything goes.

Image: John Collier portrait of Darwin from Wikimedia Commons