Moral Minds, by Marc Hauser

Which side are you on? Genes or environment? Nature or nurture? Biology or culture? If you picked the first answer to all these questions, then you are probably in a minority among readers of this newspaper. As a rule, enthusiasm for genetic influences is restricted to the extreme right. A long tradition of reactionary thinkers have appealed to genetic differences to justify economic inequality, racial discrimination and eugenics.

Still, perhaps this association of genes with right-wing views is not inevitable. Over the last couple of decades, an influential group of American academics have been arguing that you don't need to be nasty to be interested in genes. Their thought is that genes are just as important for human similarities as differences. Suppose the liberals are right that most human differences are due to environments rather than genes. We might still want to ask why humans are everywhere so similar. Why do people all over the world tell jokes, gossip, and talk to babies? These are pretty odd things to do, if you think about it. One plausible answer is that humans everywhere are driven to these peculiarities by their common genetic endowment.

This new movement marches under the banner of evolutionary psychology, and its inspiration is Noam Chomsky. Since the 1960s, he has been arguing that all humans must have innate knowledge of universal principles of grammar, otherwise young children wouldn't learn to speak so easily. As he sees it, the human brain comes ready-made with a mini-computer, or "module", that enables us to make sense of language. Evolutionary psychologists have posited modules for choosing mates, detecting cheats, understanding motives and much more. The public face of evolutionary psychology is Steven Pinker, and the movement is steadily growing in influence.

Mark Hauser is the director of the Cognitive Evolution laboratory at Harvard University and a fully paid-up evolutionary psychologist. In his new book he aims to add morality to the list of computational modules. He thinks that we all share an "innate moral grammar" that generates our intuitive moral judgements, as with the innate grammar posited by Chomsky.

Hauser has no doubts about the importance of his message. In his prologue he assures us that his "radical rethinking of our ideas on morality... supported by an explosion of recent scientific evidence" will lead to "a richly detailed explanation of how an unconscious moral grammar underlies our judgements of right and wrong".

Not everybody is bowled over by evolutionary psychology. As a discipline, psychology has long been susceptible to technological fads. John Searle, the American philosopher, likes to poke fun at the computer model of the mind by reminding us that in the middle of the last century it was common to compare the mind to a telephone exchange. Plenty of other contemporary experts have similar doubts. This isn't a matter of denying materialism or evolution. Even head-banging Darwinians like Richard Dawkins and Daniel Dennett are careful to distance themselves from the more doctrinaire precepts of evolutionary psychology.

Still, as Hauser would no doubt say, it's an empirical question. This book describes many fascinating findings from a wide range of psychological experiments. But I couldn't see that Hauser came up with anything to vindicate his faith.

Take the "ultimatum game" which Hauser discusses in detail. This experiment involves two subjects who have never met and will never meet again. Subject A is given $10, and told to split it with subject B. Subject B can either accept the split or reject it, in which case neither A or nor B gets anything. Hard-headed economists would expect A to take $9 and offer B just $1. (Why give B more? Only an idiot would prefer nothing to $1.) But the economists would be wrong. Most As offer their Bs about $4. What is more, they are quite right to do so, because most Bs will reject an offer of less, happy to forego real money to chastise A.

This is interesting. It is genuinely surprising that people behave this way. If the result held up across all societies, we might well wonder whether we have genes that force us to expect fairness. But, as Hauser explains, not everybody does it like the American college students used in most versions of the experiment. The Machiguenga people of Peru seem to think that a 9:1 split is perfectly fine, while the gift-giving cultures of Papua New Guinea reject offers of half or more, lest the recipients place themselves under an obligation.

Hauser's real expertise is infants and animals, and the book describes many ingenious studies into the ways they think. But when it comes to adult moral agents he keeps running into the same problem. He has plenty of data on the moral reactions of North American subjects, but not much to show that people are the same the world over. In the face of this difficulty, his solution is to backtrack. He explains that his universal moral grammar isn't meant to specify the details of local moral codes, only the general structure of morality. But this makes his thesis very thin.

It is only in his final two paragraphs that Hauser seems to notice that his science allows for moral divergence, and adds: "I favour a pluralistic position, one that recognises different moral systems, and see adherence to a single system as oppressive". This makes little sense. In a perfect world, sufficient doses of reason, empathy and information may be enough to resolve all moral disputes. Or so we can hope. In any case, it is clear that Hauser's promised genetic science isn't the panacea he claims.

David Papineau is professor of philosophy at King's College London; his book, 'Thinking About Consciousness' is published by OUP