If Steven Pinker's latest 500-page treatise on the brain, The Blank Slate, serves any wider purpose in the popular discussion of science issues, it will, one hopes, be the final demolition of that battle-worn slur, "biological determinism," still lugged out by the occasional critic when someone starts talking about

genes, evolution and human behavior in the same paragraph. Ever since E.O. Wilson first published the 1975 book Sociobiology--which argued that human behavior, like that of all creatures on the planet, was partially shaped by natural selection--certain factions of the left, sometimes led by creditable scientists like Richard Lewontin and Stephen Jay Gould, have lashed out at any attempt to connect human emotions and aptitudes to Darwinian explanations.

The critique has ranged from the notorious pitcher of ice water tossed in Wilson's face at a scholarly conference in the 1970s to the more erudite approach of Lewontin, Leon Kamin and Steven Rose's Not in Our Genes. But while the delivery mechanisms differed, the underlying message remained constant: Biological determinism was a rear-guard movement, the more sophisticated offspring of social Darwinism and eugenics. "Sociobiology is a reductionist, biological determinist explanation of human existence," the authors of Not in Our Genes write in a typical passage. "Its adherents claim...that the details of present and past social arrangements are the inevitable manifestations of the specific action of genes."

The trouble with a catchall phrase like "biological determinism" is that both words of the phrase are misleading or simply inaccurate. The word "biological" can refer to three different types of propositions, each with its own distinct set of implications. The first is increasingly categorized under the umbrella term "evolutionary psychology," replacing the original "sociobiology" partially because the term has become so controversial. Evolutionary psychologists, including Pinker himself, argue that our brains are not general learning machines shaped entirely by culture; instead, natural selection has endowed us with a set of "mental modules" that give us innate skills and predispositions. (We have modules for language acquisition, for face recognition, for building basic taxonomies of life forms and much else.) The second kind of "biology" at work in "biological determinism" focuses on the differences between large groups: between men and women, for instance, or between different races. The third kind addresses the question of individual genetic destiny: how much your intelligence, extroversion or phobias are heritable, and how much they are shaped by your life experience.

It should be clear from even this brief overview that the three kinds of biological determinism have utterly different social and political implications, and indeed draw upon different scientific disciplines. Evolutionary psychology addresses the shared characteristics of the human species: what unites us all, irrespective of race or culture--exactly the opposite of what a race-based inquiry into our biological roots would attempt to discover. By the same token, a researcher looking into an individual's genetic attributes would be focused on what makes us unique as individuals. So the "biological" in biological determinism can either be broadly unifying or atomizing, depending on what you're talking about.

The true straw man of biological determinism, however, is the latter term, which implies a fantasy of genetic programming in which we are all slaves to our DNA, with free will, education, culture, chance, life experience--all the nonbiological forces--relegated to the margins of who we are. Not one of the leading neo-Darwinians--Wilson, Pinker, Richard Dawkins, Robert Trivers, William Hamilton or the science writers who have helped popularize their work, like Richard Wright and Matt Ridley--has ever argued for a pure genetic determinism. You can't read more than a few pages into any of the major books written on the subject without encountering the obligatory disclaimer, making it clear that the author believes that we are greatly shaped by culture and experience, and the biological component is only a part of what makes us human. As Richard Dawkins wrote in a 1984 review of Not in Our Genes:

Rose et al. cannot substantiate their allegation about sociobiologists believing in inevitable genetic determination, because the allegation is a simple lie. The myth of the "inevitability" of genetic effects has nothing whatever to do with sociobiology.... Sociobiologists, such as myself (much as I have always disliked the name, this book finally provokes me to stand up and be counted), are in the business of trying to work out the conditions under which Darwinian theory might be applicable to behaviour. If we tried to do our Darwinian theorising without postulating genes affecting behaviour, we should get it wrong. That is why sociobiologists talk about genes so much, and that is all there is to it. The idea of "inevitability" never enters their heads.