"The new sciences of human nature." Well, why not? The old sciences of human nature didn't have such a fabulous track record. They gave us segregated drinking fountains, "invented spelling," and the glass ceiling—all consequences of scientific theories about the way human beings really are. Possibly, there is a lesson there, which is that the sciences of human nature tend to validate the practices and preferences of whatever regime happens to be sponsoring them. In totalitarian regimes, dissidence is treated as a mental illness. In apartheid regimes, interracial contact is treated as unnatural. In free-market regimes, self-interest is treated as hardwired. Maybe this is unfair to the new sciences of human nature, though. It could be that the problem with the old sciences was simply that they weren't scientific enough—that they were mostly wishful thinking projected onto dubious data about skull size and the effects of estrogen on the ability to balance a checkbook. Today's scientists might have the capacity to get right down there among the chromosomes and the neurotransmitters, and to send back reports, undistorted by fear, favor, or the prospect of funding, about what's going on. Maybe the new sciences of human nature are really scientific. It's worth a look. View more Steven Pinker is a psychology professor at M.I.T. and the author of an entertaining and popular book on language (his specialty), called "The Language Instinct," and a more wide-ranging volume, also popular, called "How the Mind Works." His new book, "The Blank Slate: The Modern Denial of Human Nature" (Viking; $27.95), recycles some of the material published in "How the Mind Works" but puts it to a more prescriptive use. Pinker has a robust faith in "the new sciences of human nature" (his phrase)—he was formerly the director of M.I.T.'s Center for Cognitive Neuroscience—but his views in "The Blank Slate" are based almost entirely on two branches of the new sciences: evolutionary psychology and behavioral genetics. These are both efforts to explain mind and behavior biologically, as products of natural selection and genetic endowment. Unless you are a creationist, there is nothing exceptionable about the approach. If opposable thumbs are the result of natural selection, there is no reason not to assume that the design of the brain is as well. And if we inherit our eye color and degree of hairiness from our ancestors we probably inherit our talents and temperaments from them, too. The question isn't whether there is a biological basis for human nature. We're organisms through and through; biology goes, as they say, all the way down. The question is how much biology explains about life out here on the twenty-first-century street. Pinker's idea is that it explains much more than some people—he calls these people "intellectuals"—think it does, and that the failure, or refusal, to acknowledge this has led to many regrettable things, including the French Revolution, modern architecture, and the crimes of Josef Stalin. Intellectuals deny biology, according to Pinker, because it interferes with their pet theories of mind and behavior. These are the Blank Slate (the belief that the mind is wholly shaped by the environment), the Noble Savage (the notion that people are born good but are corrupted by society), and the Ghost in the Machine (the idea that there is a nonbiological agent in our heads with the power to change our nature at will). The "intellectuals" in Pinker's book are social scientists, progressive educators, radical feminists, academic Marxists, liberal columnists, avant-garde arts types, government planners, and postmodernist relativists. The good guys are the cognitive scientists and ordinary folks, whose common sense, except when it has been damaged by listening to intellectuals, generally correlates with what cognitive science has discovered. I wish I could say that Pinker's view of the world of ideas is more nuanced than this. Many pages of "The Blank Slate" are devoted to bashing away at the Lockean-Rousseauian-Cartesian scarecrow that Pinker has created. What the new sciences show, he says, is that, contrary to "the romanticism of intellectuals," nurture is usually no match for nature. Rehabilitation often fails to cure violent criminals; identical twins raised separately exhibit uncanny similarities; reading bedtime stories has little effect on I.Q. Findings like these suggest that there are limits to what we can expect from efforts to make people happier, smarter, and better citizens by manipulating their environment. When revolutionaries remake society from the ground up, on the theory that a new kind of human being will emerge, or when feminists argue that if little boys played with dolls and teacups the world would be a less violent place, they are, in Pinker's view, breaking eggs with no hope of an omelette. They are simply frustrating drives and instincts that will find an outlet sooner or later. It's not nice to fool human nature.

But where does this leave us? There are limits, after all, to the idea of limits. We manipulate the environment constantly in order to shape attitudes and behavior. We employ police to intimidate people into obeying traffic signs and anti-littering ordinances; we require kids to go to school; we air-condition workplaces and provide them with coffee stations. Peer pressure constrains the expression of sexual desire. Happy hours relieve feelings of stress. Religious services inspire people to do good works. Most of life is conducted in an environment of man-made stimulants and inhibitors, incentives and deterrents. Many impulses are channelled or suppressed, and many talents and feelings are acquired, and have no specific genetic basis or evolutionary logic at all. Music appreciation, for instance, seems to be wired in at about the level of "Hot Cross Buns." But people learn to enjoy Wagner. They even learn to sing Wagner. One suspects that enjoying Wagner, singing Wagner, anything to do with Wagner, is in gross excess of the requirements of natural selection. To say that music is the product of a gene for "art-making," naturally selected to impress potential mates—which is one of the things Pinker believes—is to say absolutely nothing about what makes any particular piece of music significant to human beings. No doubt Wagner wished to impress potential mates; who does not? It is a long way from there to "Parsifal." Pinker doesn't care much for art, though. When he does care for something—cognitive science, for example—he is all in favor of training people to do it, even though, as he admits, many of the methods and assumptions of modern science are counter-intuitive. The fact that innate mathematical ability is still in the Stone Age distresses him; he has fewer problems with Stone Age sex drives. He objects to using education "to instill desirable attitudes toward the environment, gender, sexuality, and ethnic diversity"; but he insists that "the obvious cure for the tragic shortcomings of human intuition in a high-tech world is education." He thinks that we should be teaching economics, evolutionary biology, and probability and statistics, even if we have to stop teaching literature and the classics. It's O.K. to rewire people's "natural" sense of a just price or the movement of a subatomic particle, in other words, but it's a waste of time to tinker with their untutored notions of gender difference. Having it both ways is an irritating feature of "The Blank Slate." Pinker can write, in refutation of the scarecrow theory of violent behavior, "The sad fact is that despite the repeated assurances that 'we know the conditions that breed violence,' we barely have a clue," and then, a few pages later, "It is not surprising, then, that when African American teenagers are taken out of underclass neighborhoods they are no more violent or delinquent than white teenagers." Well, that should give us one clue. He sums the matter up: "With violence, as with so many other concerns, human nature is the problem, but human nature is also the solution." This is just another way of saying that it is in human nature to socialize and to be socialized, which is, pragmatically, exactly the view of the "intellectuals." The insistence on deprecating the efficacy of socialization leads Pinker into absurdities that he handles with a blitheness that would be charming if his self-assurance were not so overdeveloped. He argues, for example, that democracy, the rule of law, and women's reproductive freedom are all products of evolution. The Founding Fathers understood that the ideas of power sharing and individual rights are grounded in human nature. And he quotes, with approval, the claim of two evolutionary psychologists that the "evolutionary calculus" explains why women evolved "to exert control over their own sexuality, over the terms of their relationships, and over the choice of which men are to be the fathers of their children." Now, democracy, individual rights, and women's sexual autonomy are concepts almost nowhere to be found, even in the West, before the eighteenth century. Either human beings spent ten thousand years denying their own nature by slavishly obeying the whims of the rich and powerful, cheerfully burning heretics at the stake, and arranging their daughters' marriages (which would imply a pretty effective system of socialization), or modern liberal society is largely a social construction. Which hypothesis seems more plausible?

In 1859, Charles Darwin announced his conclusion that all life forms are the result of processes that are natural, chance-generated, and blind. There is, he thought, no "meaning" to evolutionary development. Evolution is just a by-product of the fact that organisms have to compete with one another in order to survive. If there were no struggle, if some organisms didn't have to die so that others could live, there would be no development. That is all evolution amounts to. This recognition seems to have made Darwin literally sick. But, ever since "On the Origin of Species" and "The Descent of Man" (1871), people have used Darwin's theory to explain why one or another way of managing human affairs is "natural." The notion is that a particular arrangement must have been "selected for"—as though the struggles among individuals and groups and ideas were nature's way of making sure that we end up with the best. Evolutionary psychology is therefore a philosophy for winners: it can be used to justify every outcome. This is why Pinker has persuaded himself that liberal democracy and current opinion about women's sexual autonomy have biological foundations. It's a "scientific" validation of the way we live now. But every aspect of life has a biological foundation in exactly the same sense, which is that unless it was biologically possible it wouldn't exist. After that, it's up for grabs. The other trouble with evolutionary psychology is that it is not really psychology. In general, the views that Pinker derives from "the new sciences of human nature" are mainstream Clinton-era views: incarceration is regrettable but necessary; sexism is unacceptable, but men and women will always have different attitudes toward sex; dialogue is preferable to threats of force in defusing ethnic and nationalist conflicts; most group stereotypes are roughly correct, but we should never judge an individual by group stereotypes; rectitude is all very well, but "noble guys tend to finish last"; and so on. People who share these beliefs probably didn't need science to arrive at them, but the science is undoubtedly reassuring. On one subject, though, Pinker does take an unconventional position. This is the matter of child rearing. Here Pinker relies on a 1998 book called "The Nurture Assumption," by Judith Rich Harris, which has been the object of some controversy in the field of developmental psychology. Harris claimed that "shared family environments"—that is, parents—have little or no effect on a child's personality. (Strictly speaking, she claimed that parenting does not account for the variation in differences in personality, which is what genetic science measures.) Biological siblings reared together are no more alike, or less different, than biological siblings reared in separate families. Half of personality, Harris argued, is the product of genes, and half is the product of what she called the "unique environment"—that is, the particular experiences of the individual child. Harris suggested that children's peers might be the principal source of this environmental input. This is distinctly not Clinton-era thinking. It was Hillary Clinton, after all, who sent parents of older children into a depression by announcing that personality is shaped in the first three years of life. If you missed those bedtime stories, there was apparently no way to make it up. Harris's theory makes nonsense of this anxiety, as it does of virtually all expert child-rearing advice, which Pinker calls "flapdoodle." What is personality, though? The answer turns out to be quite specific. The new sciences of human nature have discovered that personality has exactly five dimensions: people are, in varying degrees, either open to experience or incurious, conscientious or undirected, extroverted or introverted, agreeable or antagonistic, and neurotic or stable. (This is known in the literature as the Five-Factor Model, or FFM. The five dimensions are referred to by the acronym OCEAN.) All five attributes are partly heritable, and they are what behavioral geneticists look to for a definition of personality. It seems that there is no need for finer tuning, because OCEAN accounts for everything. "Most of the 18,000 adjectives for personality traits in an unabridged dictionary can be tied to one of these five dimensions," as Pinker explains. When Pinker and Harris say that parents do not affect their children's personalities, therefore, they mean that parents cannot make a fretful child into a serene adult. It's irrelevant to them that parents can make their children into opera buffs, water-skiers, food connoisseurs, bilingual speakers, painters, trumpet players, and churchgoers—that parents have the power to introduce their children to the whole supra-biological realm—for the fundamental reason that science cannot comprehend what it cannot measure. Science can measure anxiety. This is not just because people will report themselves, in surveys, to be more or less anxious; it is also because a genetic basis for anxiety has been identified. People with a shorter version of a stretch of the DNA that inhibits the serotonin-transporter gene on chromosome 17 are more likely to be anxious. That chronic anxiety is biological—that it is not caused solely by circumstance—is shown by the fact that medication containing a selective serotonin reuptake inhibitor (that is, an anti-depressant) can relieve it. (Would medication count as nurture or as nature?) But that's just the biology. The psychology is everything that the organism does to cope with its biology. Innately anxious people develop all kinds of strategies for overcoming, disguising, avoiding, repressing, and, sometimes, exploiting their tendency to nervousness. These strategies are acquired—people aren't born with them—and they are constructed from elements that the environment provides. The mind can work only with what it knows, and one of the things it knows is parents, who often become major players in the psychic drama of anxiety maintenance. The mere fact of having "the gene for anxiety" determines nothing, which is why some anxious people become opera buffs, some become water-skiers, and some just sit and stare out the window, brooding on the fact that their parents did not read them enough bedtime stories. These people are unlikely to be relieved by learning that cognitive science has determined that bedtime stories are overrated.