Steven Pinker -- How the Mind Works - Hampshire High Italian ...

Revenge of the Nerds 161terns, cells, organisms, brains, ecosystems, societies, and so on. Dozensof new books have applied these ideas to topics such as AIDS, urbandecay, the Bosnian war, and, of course, the stock market. Stuart Kauffman,one of the movement's leaders, suggested that feats like self-organization,order, stability, and coherence may be an "innate property of somecomplex systems." Evolution, he suggests, may be a "marriage of selectionand self-organization."Complexity theory raises interesting issues. Natural selection presupposesthat a replicator arose somehow, and complexity theory might helpexplain the "somehow." Complexity theory might also pitch in to explainother assumptions. Each body has to hang together long enough to functionrather than fly apart or melt into a puddle. And for evolution to happenat all, mutations have to change a body enough to make a differencein its functioning but not so much as to bring it to a chaotic crash. Ifthere are abstract principles that govern whether a web of interactingparts (molecules, genes, cells) has such properties, natural selectionwould have to work within those principles, just as it works within otherconstraints of physics and mathematics like the Pythagorean theoremand the law of gravitation.But many readers have gone much further and conclude that naturalselection is now trivial or obsolete, or at best of unknown importance.(Incidentally, the pioneers of complexity theory themselves, such asKauffman and Murray Gell-Mann, are appalled by that extrapolation.)This letter to the New York Times Book Review is a typical example:Thanks to recent advances in nonlinear dynamics, nonequilibrium thermodynamicsand other disciplines at the boundary between biology andphysics, there is every reason to believe that the origin and evolution oflife will eventually be placed on a firm scientific footing. As we approachthe 21st century, those other two great 19th century prophets—Marx andFreud—have finally been deposed from their pedestals. It is high timewe freed the evolutionary debate from the anachronistic and unscientificthrall of Darwin worship as well.The letter-writer must have reasoned as follows: complexity hasalways been treated as a fingerprint of natural selection, but now it canbe explained by complexity theory; therefore natural selection is obsolete.But the reasoning is based on a pun. The "complexity" that soimpresses biologists is not just any old order or stability. Organisms arenot just cohesive blobs or pretty spirals or orderly grids. They are