By Jesse Prinz
Beyond Human Nature: How Culture and Experience Shape our Lives
Allen Lane, 416pp, £22
It is astonishing how quickly nature has gone into retreat. Until five or ten years ago, the dominant story was that our genes were our fate. Our fixed endowments in the shape of unlearned capacities, innate modules, biologically hard-wired dispositions and evolutionary inheritances from the savannah dominated the scene, with culture and history relegated to mere bit players.
The first cracks in the consensus appeared with the realisation that genes work differently in different environments. For example, it was discovered that if rats were separated into two groups, one of which received maternal care and love while the other did not, parts of the brain grew better in the former group and they were less likely to flood themselves with stress hormones such as cortisol. So, if you want a laid-back rat, mother it properly. Epigenetic factors began to muscle in on the DNA monopoly.
Of course, in human beings we already knew - didn't we? - that such environmental factors affected children's characters. And it didn't take much guessing to suppose that it did this by making some difference to their brains. But somehow it took the addition of brain scans and neurophysiological and endocrinal data from rats to make such beliefs respectable again, so that anthropology could begin to claw back ground from biology.
Jesse Prinz, a philosopher at the City University of New York, has written an excellent guide to the current state of play. Prinz is admirably cautious about the nature-nurture dispute, which always has to come down to matters of detail and degree. His interest is in human flexibility, although he freely admits that "we need very sophisticated biological resources to be as flexible as we are". Nevertheless, it is clear where his sympathies lie. Early in the book he tells us that only "a tiny fraction of articles in psychology journals take culture into consideration". So it is time to redress the balance, and Prinz does it with insight, learning and above all a wonderful eye for the weaknesses in biological reductionist arguments.
Prinz lays out his case by first considering the difference between colour vision, which is a natural capacity with a well-understood biological underpinning, and the capacity to play baseball, which requires putting together a number of general capacities in a way that takes a great deal of nurture to develop. The question, then, is the size of the innate inventory of capacities, rules, dispositions and tendencies, shaped over time by evolution, and themselves constituting adaptations to older environments. Are they large, computationally fixed and relatively inflexible, like colour vision? Or is it more a matter of general-purpose abilities (running, balancing, throwing, remembering) exquisitely tuned by culture and learning into one form or another, like baseball?
In the former camp we have evolutionary psychologists, nativists and those who like a picture of the mind as a kind of Swiss Army knife: an aggregation of dedicated modules rigidly shaped by evolution. In the latter camp, we have those who stress general purpose learning capacities, which in one environment might enable you to become a cricketer, but in another a baseball player. At the dawn of the scientific revolution, the philosophical ancestors of the first group were rationalists such as Descartes and Leibniz, who saw the mind as ready-furnished by God with a nice array of innate capacities. The ancestors of the second group were the empiricists, who thought that we needed no such interior designer. Experience could do the furnishing all by itself.
Ever since the work of Noam Chomsky in the middle of the 20th century, our capacities with language have been one of the major battlegrounds. The trump card of Chomsky and his followers is the "poverty of stimulus" argument. This alleges that empiricism cannot account for language learning. We learn too much, too quickly, making too few mistakes, extrapolating what we learn too accurately, for this to be the result of any general empirical learning process. Out of all the myriad possible patterns linguistic systems might implement, the infant almost miraculously picks up the right one, with far too little experience or correction to explain the unfolding capacities. Only a few theorists have dared to challenge this Chomskyan consensus. And Chomskyans are certainly right that the infant cannot be doing it by consciously formulating rules, since even expert linguists often cannot do as much.
Prinz makes a strong, detailed case that statistical learning, the poster child of empiricism, can account for everything we know about language learning. Children do not just imitate, they extrapolate. They try things out. They take patterns they hear and extend them experimentally. They are unconsciously nudged into shape by the regularities in the data sets to which they are exposed. And this makes sense: the brain is designed to pick up on patterns in the environment, whether they indicate edibility in food, change in the weather, the passage of a predator, the way to cook a squirrel, or the acceptability of a new sentence. Instead of arriving packed with innate universal grammars, we come ready to pick up whatever the world is going to throw at us. The quicker we learn its ins and outs, the better.
The example may sound dry, but there is a vital humanistic lesson in the book. It has been all to easy to cite "innate" differences as justifications of the social status quo, when too often it is the social status quo that generates the illusion of the innate differences. For example, the belief that girls are naturally girlish and boys naturally boyish ignores the ubiquitous pressures to conform to the acceptable pattern, starting well before birth and reinforced throughout life. Prinz writes well about this, too. Similar remarks apply, of course, to those who, themselves belonging to the supposedly superior group, put different IQ scores or arithmetical or musical ability down to differences of race, before reflecting on the social and cultural environments of those who are being compared.
Prinz's final chapter is about sex, but I shall not spoil the plot. Suffice it to say that we are not naturally polygamous, or monogamous, or anything else, except perhaps naturally inclined to bend the truth on questionnaires. "Those who want to understand our preferences will learn more from history books than from chimpanzee troops in the Gombe," Prinz tells us. "[B]iology can help explain why we are more likely to flirt with a person than a potato, but that's just where the story begins."
From start to finish this book is a fine, balanced, enormously learned and informative blast on the trumpet of common sense and humane understanding. The story is largely optimistic but also reminds us that when things go wrong around us, we are all capable of going wrong with them.
Simon Blackburn is Bertrand Russell professor of Philosophy at Cambridge. His most recent book is "Practical Tortoise Raising and Other Philosophical Essays" (Oxford University Press, £25)