The belief that there is no such thing as human nature has come to be the core dogma of radical humanism. Marxists and feminists, left egalitarians and right-wing libertarians may disagree violently about a great many things, but they are at one in insisting that humans are categorically different from all other animals. The needs and capacities of tigers and gorillas are biologically given, their possibilities narrowly limited; but humans can transcend their animal origins and live as they choose. Marx gave a canonical formulation of this view when he declared that there is no human essence, only a changing ensemble of social relations; but it is by no means confined to Marx and his disciples. Jean-Paul Sartre in his existentialist days, Ortega y Gasset and the Tory philosopher Michael Oakeshott all shared this humanist creed, each of these (otherwise very different) thinkers writing that man has no nature, only a history.
The denial of human nature spans many philosophies and all political parties, but it is most adamant on the left. It is not hard to see why. Human nature is a stumbling block to believers in progress. If humans are like other animals, they cannot be expected suddenly to change their ways. Science may yield new forms of knowledge and new technologies, governments and economic systems may change, sometimes for the better, but the basic traits of human behaviour will remain the same. Even the most revolutionary transformation of society will leave human needs and motives much as they have always been.
For anyone who has inherited the grandiose hopes of Enlightenment thinkers such as Marx, this is an intolerably dispiriting prospect. It is only to be expected that they should seek to evade it. Accordingly, left-leaning social scientists and philosophers have waged an unending war of attrition against the idea of human nature. Many have argued that human behaviour is largely the product of cultural conditioning. Some - such as the American pragmatist philosopher Richard Rorty - have maintained that the very idea of human nature is a mere cultural construction, whose content changes along with shifting modes of power and discourse. What these thinkers have in common is the belief that when human beings come into the world, they are tabulae rasae, blank slates on which societies inscribe their differing beliefs and values.
That humanists should join forces in denying the existence of human nature is curious enough. What is even more curious is that they all proclaim themselves to be Darwinists. Darwin teaches that we are animals. Even so, humanists insist, we are not limited by our biological natures. Using our capacities for choice, inquiry and invention, we can alter our environment and thereby ourselves. Godlike, we can be our own makers. If there is a modern creed, this is it.
In practice, the denial of human nature has been disastrous. All the great political experiments of the 20th century - communism, the more radical varieties of fascism and the fleeting fantasy of "global democratic capitalism" - presumed that human behaviour can be fundamentally changed by an alteration in social arrangements. In each case, the experiment has ended in disappointment. Needless human suffering has flowed from the belief that there is no such thing as human nature.
It is still not enough, because an idea has harmful consequences, to show that it is mistaken. For that, we need rigorous and dispassionate analysis, which is precisely what Steven Pinker provides in his magisterial and indispensable new book.
There have been several statements of the case for human nature. Perhaps the most elegant is E O Wilson's On Human Nature (1978), a book that combines uncompromising intellectual objectivity with a tragic and poetic vision of what Darwinism implies for human hopes. Every intellectually literate person should read Wilson. For the most comprehensive and exhaustive argument for the reality of human nature, however, they should turn to Pinker.
The Blank Slate provides an invaluable survey of the evidence showing that what Pinker calls the "official theory" - that the human mind is in some deep way a social or cultural construction - is false. Both genetics and research in the advancing science of the brain show the human mind to be rooted firmly in the biology of the human animal. Contrary to Descartes, our minds are not mysterious entities directing our bodies from outside. They are an integral part of our animal equipment. Equally, contrary to Marx and to a long line of sociologists such as Durkheim, they are not primarily products of socialisation. Human responses vary somewhat from culture to culture; but the components of the human repertoire are universal. Among a host of other species-wide features are common facial expressions, a belief in superstition and an innate propensity to learn language as identified by Chomsky. Underneath the surface differences of physical appearance and local culture, the human species is one.
Pinker's book contains an overwhelming argument against the theory that the human mind is a social construct. But it is far from being a mere diatribe. It is also a wide-ranging and unfailingly sensible discussion of the ethical and political implications of accepting that we have a common nature. As Pinker points out, nothing of ethical importance follows logically from the truth that human mental capacities are largely hard-wired. Certainly, that humans are born with different talents and abilities does not mean they should be treated as being of unequal worth. Nevertheless, the scientific demonstration of the reality of human nature does have some political implications, and - as Pinker shows very clearly - these are consistently anti-utopian. To take only one of several examples that Pinker discusses, the human propensity to violence is built in to the human animal. It is not a response to media portrayals of violence, nor can it always be explained as a reaction against injustice. Humans are extremely violent animals. That does not mean violence cannot be controlled. Rather, it must be controlled. If we are skilful and determined in dealing with the causes of war, we can have a more peaceful world. We cannot have one in which the risk of violent conflict does not exist.
In an interesting aside, Pinker notes that the view of human nature which is emerging from science has more in common with that defended by Christian thinkers and by Freud than it does with theories such as Marx's. This is a point worth further elaboration, because it suggests another curious turn in the history of ideas. Enlightenment thinkers took up the scientific study of human behaviour in the hope of transforming the human condition. The result of scientific inquiry, however, is to vindicate a secular version of the idea of original sin.
John Gray's latest book is Straw Dogs: thoughts on humans and other animals (Granta)