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.

The idea that we are a mix of nature and nurture would seem to be common sense by now. But as Pinker demonstrates, the nature deniers continue to argue that beyond the basic support systems–breathing, excreting–our personalities are the product of our social existence, arriving courtesy of our parents, teachers, peer groups, media, dominant ideologies and cultural norms: the product, in other words, of our history, both personal and public. This is what Pinker calls the hypothesis of the “blank slate.” It is a strange sort of human exceptionalism. Unlike all the other organisms on earth, which clearly arrive with a sophisticated set of instincts designed to exploit the parameters of their environment, human minds are merely abstract learning machines, born with no innate proclivities other than to soak up information along the way. The blank slate has turned out to be a way of drawing a line in the sand against the last 150 years of Darwinian encroachments. Sure, we share a basic body plan with all the vertebrates and a respiratory system with our fellow mammals, and perhaps even 98 percent of DNA with our chimpanzee cousins. But the human mind is another matter.

Unless you’re a creationist, that sort of exceptionalism should seem preposterous on the face of it: Both our brains and our bodies share a common ancestor with the apes–you can’t have one and not the other. But the more interesting question–and the one Pinker spends the most time unraveling in The Blank Slate–is why that exceptionalism should prove to be so appealing to liberals and leftists who otherwise count themselves as proud defenders of the Darwinian faith. The argument for the blank slate turns out to be a strange kind of Not in My Backyardism: We need to have Darwinian theory in those Kansas schools, but we don’t dare use it to understand what’s going on in our own heads.

Trained as a linguistic psychologist whose specialist work has focused on irregular verbs, Pinker has made a name for himself as one of evolutionary psychology’s most appealing ambassadors, with a series of bestselling books summarizing an astonishingly wide body of work: The Language Instinct (1994) looked at the mental module for language processing, first proposed several decades ago in Chomsky’s idea of a generative grammar underlying all human language, and refined by subsequent developments in neuroscience and evolutionary theory. How the Mind Works (1997) extended the argument to a broader toolbox of mental modules, explaining how the mind evolved to process complex visual information, treat family members different from nonrelatives, enjoy certain types of landscapes more than others and dozens of other distinct traits. Both books were laced with implicit and explicit critiques of the blank-slate hypothesis, and How the Mind Works occasionally hinted at the political implications of overturning it. But as the title of his latest book suggests, Pinker has now brought the politics of the blank slate to the foreground. It may not convince everyone of the merits of evolutionary psychology, but it should certainly undermine the default assumption that the Darwinian theory of the mind is implicitly a reactionary one.

The weakest argument against evolutionary psychology–and the one, in my experience at least, mostly likely to be offered up during a dinner-party conversation–has always been the Nazi-baiting one: The Final Solution was built on the back of social Darwinism, which was in turn built on the back of The Origin of Species itself. From that awful lineage, the argument goes, any attempt to apply Darwinian theory to human society should be stopped in its tracks, before the inquiry runs its inevitable course to the gas chambers. Of course, if you applied this logic everywhere, you’d be renouncing much more than the neo-Darwinians: Should we abandon the germ theory of disease because the Nazis used it to justify their anti-Semitism? Stalin was certainly quite attached to the idea of worker collectives; should we renounce all modern-day labor unions because of the Gulag and the Great Purge? And, as Pinker suggests at numerous points in the book, while the Darwinian tradition was invoked to justify some horrific political ends, the blank-slate hypothesis has its own sordid past: the totalitarian regimes that believed the worker could be remade into a new kind of man, precisely because human nature was thought to be nonexistent, a malleable fiction shaped purely by historical circumstance. When people evoke the Nazis when talking about evolutionary psychology, it is the logical equivalent of responding to someone talking about the importance of culture in shaping our identity by saying: “I suppose then that you support the State separating children from their parents and forcibly re-educating them.” Carry Darwinian logic to absurd extremes and you get Auschwitz. Carry the blank slate to absurd extremes and you get the Cultural Revolution. But neither history is relevant if we stay away from the extremes, if we accept that we possess a kind of dual citizenship in the worlds of nature and nurture, with both forces contributing to who we are.

The irony is that once you get past the Nazi-baiting, there is much for progressives to embrace in the sciences of human nature. Perhaps the most important is its unifying tendency, its insistence on a kind of mental toolbox shared by the most “enlightened” Westerners and the most “primitive” hunter-gatherers of Papua New Guinea.

Natural selection works to homogenize a species into a standard overall design by concentrating the effective genes–the ones that build well-functioning organs–and winnowing out the ineffective ones. When it comes to an explanation of what makes us tick, we are thus birds of a feather. Just as we all have the same physical organs (two eyes, a liver, a four-chambered heart), we have the same mental organs. This is most obvious in the case of language, where every neurologically intact child is equipped to acquire any human language; but it is true of other parts of the mind as well. Discarding the blank slate has thrown far more light on the psychological unity of humankind than on any differences.

The most compelling attempt to date to build a thorough inventory of humanity’s basic toolbox comes from the anthropologist Donald Brown. Inspired by Chomsky’s idea of a “universal grammar”–the deep syntax shared by all human languages–Brown set out to document the basic social patterns, beliefs and categories shared by all known human societies, without exception. Pinker devotes an entire appendix to Brown’s list, which has a strangely moving, abbreviated style: “cooking; cooperation; cooperative labor; copulation normally conducted in privacy; corporate (perpetual) statuses; coyness display; crying; cultural variability; culture; culture/nature distinction; customary greetings; daily routines; dance; death rituals…”

There is much for the left (and the right) to both condemn and admire in this litany; for every “cooperative labor” there is a “females do more direct childcare.” But the first thing that should be noted about Brown’s list is its inclusiveness: We may in fact possess an innate tendency to divide the world into “in groups” and “out groups,” but the first instinct of evolutionary psychology is to group us all together in the shared family of human universals. Even if we don’t always like the traits we find there, that unifying impulse should be at the heart of any progressive politics, not an outcast from it. Pinker quotes Chomsky on this very point:

A vision of a future social order is…based on a concept of human nature. If, in fact, man is an indefinitely malleable, completely plastic being, with no innate structures of mind and no intrinsic needs of a cultural or social character, then he is a fit subject for the “shaping of behavior” by the State authority, the corporate manager, the technocrat, or the central committee. Those with some confidence in the human species will hope this is not so and will try to determine the intrinsic characteristics that provide the framework for intellectual development, the growth of moral consciousness, cultural achievement, and participation in a free community.

Of course, the one place in which the neo-Darwinians have in fact emphasized differences over commonalities is the fraught world of the sexes. Because so much of natural selection is predicated on reproductive success or failure, and because men and women have such differing biological stakes in the act of reproduction, it is inevitable that natural selection would craft slightly different toolboxes for each sex. This is no problem for the many schools of feminism that embrace the “different but equal” assessment of the sexes, but it is a major irritant for those on the left who imagine all gender differences to be the product of cultural biases. I suspect, though, that the sexual blank slate isn’t long for this world, for several reasons.

For one, the science is increasingly making its advocates into Flat Earthers. Viewed with modern imaging technologies, men’s and women’s brains are nearly as distinct from each other as their bodies are. As Pinker writes: “Men have larger brains with more neurons (even correcting for body size), though women have a higher percentage of gray matter. (Since men and women are equally intelligent overall, the significance of these differences is unknown.) The interstitial nuclei in the anterior hypothalamus, and a nucleus of the stria terminalis, also in the hypothalamus, are larger in men; they have been implicated in sexual behavior and aggression. Portions of the cerebral commissures, which link the left and right hemispheres, appear to be larger in women, and their brains may function in a less lopsided manner than men’s.” And of course, those brains–and the bodies they are attached to–are partially shaped by two totally different kinds of hormones, the androgens and the estrogens, which play a key role both in development and adult life experiences. Men and women are most certainly not from Mars and Venus, but it is entirely fair to say that they are on different drugs. A world in which the sexes were entirely mentally alike might be a better world, though it might also be a little duller. But the truth is, that is not the world we inhabit, so we might as well build a feminist politics around this fact, rather than building on the illusory sands of the sexual blank slate.

Besides, the news for feminists isn’t necessarily bad, as writers and scholars like Barbara Ehrenreich and Sarah Blaffer Hrdy have argued in recent years. Women may turn out to be more collaborative, on average, and the stronger connection between their left and right hemispheres may make them more adept at integrating emotional, intuitive understanding with logical decision-making. Most of the crude gender stereotypes that emerged with the first round of sociobiology in the 1970s have been replaced with much more nuanced accounts. Darwinian logic predicts that women will be more discriminating about their partners, and more attentive to their children, than men, but Hrdy has convincingly shown that strategic adultery makes Darwinian sense too, an insight corroborated by famous studies showing that where paternity was in question, up to 25 percent of American and Canadian children were not in fact conceived by the man claiming to be their father. Darwinian anthropologists have argued that the most alienating environment possible for a mother–the one furthest removed from the ancestral hunter-gatherer lifestyle our brains evolved in–is the stay-at-home suburban mom, disconnected from extended family, cooperative work and the social bonds of tribal life. As Matt Ridley argues, during a discussion of labor divisions in hunter-gatherer communities: “None [of this material] says anything about the woman’s place being in the home. After all, the argument goes that men and women both went out to work in the Pleistocene, one to hunt, the other to gather. Neither activity was remotely like trooping off to an office and answering telephones all day. Both sexes are equally unsuited to that.”

This is not meant to sugarcoat the sexual lessons of evolutionary psychology. There are no doubt arguments that will offend people: At the very pinnacle of achievement, men might prove to be, on average, better mathematicians or theoretical physicists than women. (Though women might just as easily prove more accomplished at the social interactions and empathy so critical to modern politics.) But even if evolutionary psychology does unearth some unsavory data on the sexual divide, it’s essential to remember two key principles. First, we’re talking about averages here, not absolutes. Men on average are more prone to violence than women, but any given woman might well be more violent than any given man. Second, and perhaps more important, the tendencies that evolutionary psychologists describe are not set in stone; violence isn’t a software program that male brains are forced inexorably to run. In fact, most evolutionary psychologists shun the word “instinct” precisely because it implies something too fixed, too inescapable. Instead, they use the phrase “prepared learning.” Natural selection doesn’t hand down a strict playbook for action–it offers hints and clues instead. We find it easier to learn strategies that are part of our toolbox, while other strategies that weren’t adaptive in our ancestral environment don’t come so easily to us. You have to go to school to learn how to read, but no one goes to school to learn how to read facial expressions, although it is an incredibly sophisticated art. We’re quick to develop phobias about spiders and snakes–which posed a major threat in our ancestral environments–but we rarely develop phobias about much more common twentieth-century killers, like electricity or SUVs. You’re vastly more likely to be killed by a car than by a garter snake, but it’s the snake that sends chills down your spine, even if you know it’s harmless. Those chills are a kind of evolutionary trace memory, a message from the millions of ancestors who survived to pass down their genes partially because they had a useful fear of snakes.

But whatever we’re prepared to learn can be unlearned under the right circumstances. And the fact that we’re prepared to learn a certain type of behavior says nothing about the political merits of that behavior. Men may be prone to violence, but that doesn’t mean we have to accept violence as a society. We overcome our so-called instincts all the time with no political repercussions whatsoever. We fly in planes and work in skyscrapers despite a fear of heights that natural selection has reasonably endowed us with. That doesn’t make life at 30,000 feet immoral. It just makes it a little more difficult to pull off than life on the ground, where natural selection expected us to be.

The practical details of prepared learning–how it comes about, and how it differs from the traditional notion of instinct–is one of the most tantalizing elements of The Blank Slate. Pinker is devastating in the chapters devoted to bulldozing the blank-slate hypothesis, and he offers a fascinating, if brief, overview of the current debate among scientists researching the biology of human nature, dividing the field into “East” and “West” poles: “Cognitive scientists at the East Pole suspect that [mental] modules are differentiated largely by the genes; those at the West Pole suspect they begin as small innate biases in attention and then coagulate out of statistical patterns in the sensory input.” But the book quickly switches focus to the social and political implications of the Darwinian mind, and while Pinker outlines them with characteristic eloquence and humor, the material is more familiar than the other sections, overlapping with arguments presented in Robert Wright’s The Moral Animal, Matt Ridley’s The Origins of Virtue or even Pinker’s own How the Mind Works. I suspect the book would have been even stronger if Pinker had spent more time explaining not just the politics of human nature but how we think it actually influences our behavior. There’s a world of difference between telling people they’re slaves to their genetic instincts and telling them that their brains are slightly biased toward learning certain skills more readily than others. The latter is undoubtedly more reassuring, but it requires a new vocabulary, somewhere between the crude reductionism of “a gene for x” and the cultural relativism of the blank slate.

Contrary to what its critics say, evolutionary psychology does not threaten our ability to assess and transform our social and cultural landscapes. Quite the opposite–understanding the particular channels that we’re prepared to learn can throw into sharper relief the achievements of culture. Knowing something about our reproductive drives and our tendencies toward violence makes the extraordinary drop in murder and birthrates experienced by many Western countries over the past few centuries all the more impressive. And just because our mental modules are implicated in political issues, that’s no reason to hand over our societal reins to the evolutionary psychologists. To include biological explanations in a discussion of human society by no means eliminates the validity of other kinds of explanations. What Pinker and E.O. Wilson are proposing is not biological determinism but rather biological consilience: the connecting of different layers of experience, each with its own distinct vocabulary and expertise, but each also possessing links up and down the chain:

Good reductionism (also called hierarchical reductionism) consists not of replacing one field of knowledge with another but of connecting or unifying them. The building blocks used by one field are put under a microscope by another. The black boxes get opened; the promissory notes get cashed. A geographer might explain why the coastline of Africa fits into the coastline of the Americas by saying that the landmasses were once adjacent but sat on different plates, which drifted apart. The question of why the plates move gets passed on to the geologists, who appeal to an upwelling of magma that pushes them apart. As for how the magma got so hot, they call in the physicists to explain the reactions in the Earth’s core and mantle. None of the scientists is dispensable. An isolated geographer would have to invoke magic to move the continents, and an isolated physicist could not have predicted the shape of South America.

There is no good reason that progressive politics couldn’t be built on top of a comparable chain: Neuroscientists explain how the brain’s underlying electrochemical networks function; evolutionary psychologists explain how and why those networks create channels of “prepared learning”; sociologists explain what happens when those channels come together in large groups of individual minds; political theorists and ethicists explore the best way to structure society based on those patterns of group behavior, and the individual needs and drives contained within them. Including a few layers of biological knowledge in this chain doesn’t hijack the process; it doesn’t turn us into genetically programmed robots. In fact, it might well make our cultural systems more effective by showcasing useful avenues to explore and suggesting areas where our prepared learning may create too much resistance. The more we understand our nature, the better we’ll be at nurturing.