The book is stylishly presented, with a memorable dust jacket - the prettiest “bell curve” ever - over its pointedly black and white binding, and elegant print and paper. It is interestingly written, skilfully argued and learnedly “referenced” and annotated. And it deals with an important psychological and social problem which in some form or other touches every one of us.

What then is the substance of its argument? And why has it evoked so much discussion, derision, objection and downright fury?

The authors start with an apology: “We are not indifferent to the ways in which this book, wrongly construed, might do harm . . .” They also explain that their book “can be read at several levels”: the simple introductory, conveniently precied at the start of chapters; at the level of the main technically documented text; or one can go the whole hog and take in 5 appendices and 280 pages of notes and references.

The USA, and presumably the rest of the Western world, we are told, finds it difficult to use its human resources to best advantage, and to solve the consequent social and economic problems.

One factor basic to human achievement, which the authors, somewhat disingenuously, say has been consistently overlooked is intelligence - “smartness” as they like to call it. Intelligence largely determines education, and hence occupation, wealth and status. It can, they maintain, be measured accurately by IQ and related tests, and is probably the most reliable and valid predictor of worldly achievement so far devised. And intelligence is largely inherited. Despite many efforts to improve it by environmental enrichment and especially by remedial and compensatory education, little lasting gain, they argue, not quite accurately, has so far been demonstrated.

Because society is becoming increasingly democratic, high IQ measurements have been found in ever broader social strata. Competition for the best schools and universities has become fiercer and the old birth elite has been replaced by a socially mixed Ivy League population. At Harvard, quaintly designated “a parable for . . . the nation’s university system”, there were by 1960 more ex-public (in the American sense) than ex-private school students, the proportion of New England students had dropped by a third since 1952, and the number of applicants rejected had doubled from one third to two thirds. “Thus in eight years Harvard had been transformed from a school primarily for the northeastern socioeconomic elite into a school populated by the brightest of the bright,drawn from all over the country”.

This massively increased access to higher education, the authors report, was generally regarded as one of the great American success stories and an example to the rest of the world.

But education according to cognitive ability, they point out, is also divisive, and the widening gap between those with and without education extracts a heavy social price. In particular, the ever more accurate sifting by IQ has revealed significant differences between ethnic groups, with American blacks scoring consistently lower than American whites or East Asians. (Mean white IQ around 100, mean black around 85). Hernstein and Murray try to get round this by proposing that the fact that black people on average have a lower IQ is not relevant when one deals with an individual black person: you cannot predict what an individual can do from his IQ score. But elsewhere in the book they repeatedly appear to take it for granted that you can. It is here that one’s growing unease begins to turn into a parting of the ways.

Although the evidence for IQ improvement following environmental improvements is neither overwhelming nor consistent, it does exist, especially in adoption studies. Heritability is not the same as immutability. Diet can increase a person’s “inherited” physical height. Even in lowly rodents split litter studies have shown that enriched environments can increase the number of synapses in the brain and hence the individuals’ ability to learn - they become “smarter”. Herrnstein and Murray concede that better research, and more awareness of the complexity of the concept of the human environment, is conceivable. They could have made more of these hopeful possibilities had their gut feelings so dictated. Instead, they give the impression that the environmental evidence for IQ improvements can only get weaker, since anything that might make it stronger has already been tried.

The recipes for social policy become bleak. Don’t waste money educating those of low cognitive ability. Don’t provide state welfare; it merely encourages low ability women to bear low ability babies - a recommendation which readers familiar with early eugenics will recognise.

All this gets gloomier when the authors put the frighteners on their readers with their vision of the future - “The Way We are Headed”. They expect cognitive stratification to lead to an increasingly isolated cognitive elite, a merging of the cognitive elite with the affluent, and a deteriorating quality of life for people at the bottom end of the cognitive ability distribution. Unchecked, they say, these trends will lead the USA towards something resembling a caste society, with the “underclass mired ever more firmly at the bottom, and the cognitive elite ever more firmly anchored at the top”. In such a meritocracy racial tensions are bound to increase, hostilities become overt and a substantial part of the population reduced to living in versions of the Indian reservation. At the very least it will become harder than hitherto for people of low cognitive ability to live meaningful and dignified lives.

What is Herrnstein and Murray’s way forward? Having downgraded the intellectually weak, they seek ways of living with them. “A Place For Everyone” is their last chapter.

It ends rhetorically: “Inequality of endowments, including intelligence, is a reality. Trying to pretend that inequality does not really exist has led to disaster . . . It is time for America once again to try living with inequality . . . understanding that each human being has strengths and weaknesses . . . that the success of each human life is not measured externally but internally; that of all the rewards we can confer on each other, the most precious is a place as a valued fellow citizen”.

One’s verdict about this book can also be made at several levels, as indeed emerges from the copious reviews. One can welcome it as a readable and richly documented expose of naturenurture issues. Or, less favourably,one can regard it as a biased though painstaking update of long standing problems and controversies. Or one can chide it for what some have regarded as its hidden political agenda, stratifying society from the Olympian heights of Harvard more or less permanently into intellectual haves and have-nots. And so on. It is a pity that the first named author died shortly before the book came out. De mortuis nil nisi bonum.

Hannah Steinberg is Visiting Professor in Psychology, Middlesex University.