Steven Pinker has a new book out, The Blank Slate. We have been closely observing and reporting on the reception of this particular volume of science for the public, because that reception and the probable reasons for it are closely related to the subject matter of Butterflies and Wheels. Evolutionary explanations of human nature and behavior and ways of thinking make many people very suspicious and afraid, and hence willing to make some highly dubious arguments.

But as many people have noticed and pointed out in the last few years (e.g. E.O. Wilson in The Philosophers’ Magazine), the tide does seem to be turning. Pinker’s book has been getting a largely favorable or at least attentively respectful hearing, including even a favorable review in the US magazine The Nation. Steven Pinker generously took some time from his busy schedule complete with book tour, to answer some questions for us.

Butterflies and Wheels: You wrote The Blank Slate to address the fears people have about evolutionary psychology. Although the days of emptying pitchers of water over peaceable entomologists may be over, I’ve noticed that many opponents of the field still resort to highly questionable tactics, including guilt by association, confusion of terms, loaded questions. Are there any critics of evolutionary psychology you respect? Any who have doubts about the evidence, the methods, the interpretations, but pose the questions without resorting to rhetoric or consequentialist arguments?

Pinker: If “evolutionary psychology” just means bringing evolutionary biology to bear on the human mind, frankly I don’t think there could be honest criticism of evolutionary psychology, because it would simply be obscurantism or disciplinary parochialism. It would be in effect declaring that the insights of one discipline must never be brought to bear on another, as if one were attacking neuroscience, or sociolinguistics, or the history of science. This is especially true given that evolutionary thinking is already pervasive in the less politically sensitive areas of psychology, like perception and motivation. It would be perverse to insist that researchers in stereo vision not be allowed to take into consideration the evolutionary function of being able to see in depth, or if scientists who study thirst were condemned for analyzing how thirst works to keep the body’s fluids and electrolytes in balance. Ultimately that is what evolutionary psychology is about, but applied to more contentious domains cognition and the social emotions.

Now, “evolutionary psychology” has also come to refer to a particular way of applying evolutionary theory to the mind, with an emphasis on adaptation, gene-level selection, and modularity. Obviously that can be criticized, just like any other empirical theory; some of the sharper critics include David Sloan Wilson, Elliot Sober, Robert Boyd, and Sarah Blaffer Hrdy.

But ultimately “evolutionary psychology” is not a single theory but a large set of hypotheses about particular topics, and any one of them can be, indeed, should be, criticized, just like any scientific hypothesis. Indeed, just about every concrete hypothesis in evolutionary psychology has come under criticism in the technical literature (and been defended in turn), just like the rest of empirical psychology. Did a preference for symmetrical faces evolve because symmetrical organisms are fitter and hence better mates, or does the visual system like symmetrical patterns even in artifacts, where mating is irrelevant? Are people especially good at detecting logical violations when they pertain to social contracts, or can they detect them more generally, whenever such a violation is relevant to our current interests? Can the nongenetic variation in personality be explained in terms of sibling competition over parental investment, in terms of carving out a niche in a peer group, or in terms of sheer chance? The researchers who raise these objections to hypotheses emerging from evolutionary psychology are, of course, doing their job as scientists. Many of these issues can take decades to resolve, again, just like the rest of psychology. It is conceivable that when the dust settles not a single hypothesis motivated by evolutionary biology will survive (but I doubt it).

B and W: One reservation that I hear from rational people is the “just-so stories” aspect. That evolutionary explanations of human nature can operate the way Freud’s did: simply twist and turn to meet objections, interpret the evidence so that it fits the theory rather than adjusting the theory. Is there any merit to this idea, or is evolutionary psychology just as falsifiable as any other science?

Pinker: “Evolutionary psychology” is an approach and a set of theories, not a single hypothesis, so no single experiment can falsify it, just as no single experiment can falsify the theory of evolution or the connectionist (neural network) approach to cognition. But particular hypotheses can be individually tested, such as the ones on the relation of symmetry to beauty or the relation of logical cognition to social contracts, and tests of these are the day-to-day activity of evolutionary psychology. Journals such as Evolution and Human Behavior are not filled with speculative articles; they contain experiments, survey data, meta-analyses, and so on, hashing out particular hypotheses. And as I mentioned above, over the long run the approach called evolutionary psychology could be found unhelpful if all of its specific hypotheses are individually falsified.

B and W: You discuss, in The Blank Slate, the way an excessively optimistic view of human plasticity can lead to social engineering, coercion, and genocide. But you also point out that though we have drives and instincts that served us well in the distant past but don’t serve us well now, we also have a cerebral cortex that can override those drives. Is there any tension between those two thoughts? Is there any way to distinguish between dangerous social engineering on the one hand, and necessary laws that seek to restrain such drives, laws against rape for example, on the other?

Pinker: I don’t think there is a contradiction because I don’t think the cerebral cortex is an infinitely malleable substance or an all-powerful problem solver. In language, a finite set of rules can generate an infinite set of sentences; not just any old set (million-word sentences, programs in Java, musical notation, humpback whale songs, etc.), but only sets conforming to “Universal Grammar.” Likewise there is an infinite space of possible thoughts and goals, but they are subject to the quirks and limitations of human nature.

Your question about a middle ground between coercive social engineering and necessary restraints on antisocial behavior is basically the age-old question (debated by Hobbes, Rousseau, Locke, and the framers of the American constitution, among others) of whether there can be a middle ground between anarchy and totalitarianism. Democratic government, the rule of law, and civil-libertarian restraint on the power of government and the police are, in my view, solutions that do make such distinctions. Ultimately the distinctions hinge on the promotion of human well-being and the reduction of human suffering – some medium-sized amount of government coercion (constitutionally limited, and operating with the consent of the governed) seems to maximize this function better than anarchy or totalitarianism.

B and W: It seemed to me that the audience was at least not hostile when I saw you on your book tour. Indeed, when one man tried the rhetorical move of wondering what use future tyrants might make of your books and you replied that you wouldn’t worry about it as long as they read them with understanding, the audience applauded. Has the reaction been generally favourable so far? And was there any difference between the responses in the UK and the US?

Pinker: People who come to my talks are not a random sample, of course, but you are correct that I have not received anything like the abuse that greeted E. O. Wilson or Richard Herrnstein in the 1970s. The only truly intemperate reaction was from a British psychoanalyst who (correctly) inferred that if people’s personalities and neuroses are not shaped by parental treatment in the first six years of life, he and his colleagues are guilty of malpractice. I also have received a small number of nasty – and I would say grossly unfair — reviews from academics and journalists who vaguely sensed that their 1960s-era leftism was not being affirmed by the book, who could not put their finger on anything wrong with the arguments, and who resorted to distortion and sweeping dismissal. But that has been true of a minority of the reviews and probably could be expected of any book that takes on controversial subjects. Indeed, with the exception of the man you noticed, I have not received any hostile reaction among the hundreds of audience questions and pieces of correspondence I have received so far.

One of the reasons is that the climate has changed – I first noticed this a few years ago when my the students in my classes at MIT were not outraged by hearing about research on, say, violence or sex differences that would have been inflammatory a few years ago. (They are a whole new generation – it was their parents, or even their grandparents, who were carrying placards in the 1960s and 1970s!) Also, whereas Wilson was blindsided by the attacks, not realizing that his proposals might have political implications, The Blank Slate is about the political implications (and non-implications) of human nature, and shows how an acknowledgment of human nature does not, in fact, justify racism, sexism, reactionary politics, or moral nihilism. Anyone who is morally incensed by the book cannot have read it.

Steven Pinker is Peter de Florez Professor of Psychology at Massachusetts Institute of Technology. He is the author of The Blank Slate, How the Mind Works, and The Language Instinct.