IQ: the brilliant idea that failed, by Stephen Murdoch

Nobody observing recent debates about our children's schooling can have failed to be moved by the upwelling of Conservative compassion for those able and worthy working-class youngsters whose potential can only be fulfilled via places at grammar schools. No segment of the nation, evidently, is dearer to the Tory heart. As for the schools, Conservatives do not just hold them dear; they hold them in awe. The totemic power of the grammar school arises from its fundamentally conservative nature. Whatever today's grammars are like, in the conservative mind they are bastions of proper standards. They inculcate social, cultural and academic grammar. Pupils conform to the discipline of Latin declensions instead of degrading what's left of English into txt msgs.

Doing as the traditional grammar schools bid was more a matter of duty, like military service, than personal development. But when British educationalists began to promote the use of intelligence tests to assess potential, they were attempting to centre education upon the child. Many adults schooled in the era of the universal 11-plus examination remain profoundly grateful to that selection system, in which intelligence testing was embedded, for giving them the opportunity to pursue excellence. But many others still feel the stigma of being labelled as failures before their teens.

That era is brought vividly to life by Stephen Murdoch, an American writer, who interviewed people schooled in South Wales under the shadow of the 11-plus. On the day the results came out, adults would stop children and ask if they had passed. A child who answered "yes" would likely get a sixpence. Those who said "no" knew that as far as the adult world was concerned, they were factory fodder.

Murdoch's efforts to develop a transatlantic perspective on IQ come as a pleasant surprise in a field shaped by US concerns. So does his engaging and lively style. Perhaps uniquely among books about IQ, this one is a page-turner. His sympathy for students and teachers alike makes it easy for the reader to warm to him in turn. The trouble is that he makes it too easy for himself and the like-minded readers to whom this book is addressed.

His case is that IQ tests started out as a modest and commendable attempt to diagnose learning difficulties, but have been promoted far beyond their ability. They do not really measure intelligence, and have been exploited for dubious or pernicious ends. The argument is canonical, set out in the 1980s by Stephen Jay Gould in The Mismeasure of Man. The critics and the IQ psychologists have been talking past each other ever since. Critics point to individuals whose fortunes do not correspond to their IQ scores; IQ advocates look at the masses and judge that, statistically speaking, people end up as the tests predict. Critics contend that IQ tests are social constructs that measure social constructs; advocates maintain they are scientific instruments that measure substantially natural qualities. This book continues the anti-dialogue.

It does venture close to the world of "g", as the factor of general intelligence held to underlie the test scores is termed, but quickly shies away. Murdoch never really dares to confront the interminable correlations of what the biologist John Maynard Smith used to call the " g groupies". This keeps the narrative free of numbers, and safely within its comfort zone. It also fails to convey how the world looks to the cult of g, in which general intelligence explains everything.

In the early days of testing, as Murdoch recounts, intelligence was taken up as an explanation for morality. In particular, sexual activity on the part of unmarried young women was associated with "feeble-mindedness", a level of mental ability said to leave them incapable of reflecting upon their behaviour and exercising restraint. Where that led is illustrated in the story of Carrie Buck, a woman institutionalised and sterilised on the grounds of feeble-mindedness, having become pregnant by rape.

Hers was a political injustice, the bid to sterilise her turned into a test case that could establish a legal precedent. As Murdoch notes, her feeble-mindedness was more a matter of doctors' opinion than test scores. Like everybody, when it came to intelligence, they started with minds made up.

The history of coercive eugenics now serves as a moral anchor for scepticism about IQ and suspicion of its proponents. What the latter lack in coercive power, however, they make up for in certainty. The g factor sits at the heart of a hereditarian vision in which variations in all psychological traits are substantially influenced by variations in genes. IQ scores are seen as the best available indicators of how people will fare in life. Somebody with an IQ of 85 can drive a truck, whereas the entry IQ level for doctors is around 115 – though the smartest truck drivers are only just behind them.

To its enthusiasts, g is about much more than cleverness. It is about character. Low-IQ people are considered unable to set long-term benefits against instant gratification. High-IQ people are capable of thinking things through, choosing salad instead of chips, and moving next door to grammar schools before house prices go exponential. People reach their station in life through their efforts, but their capacity for effort is largely in their genes.

This identification of the brightest as the best connects today's hereditarianism with that earlier period, in which low intellect was first identified as the root of indigence and immorality. But in those days intelligence was a cause, the defence of civilisation from internal decay. Today IQ theory aspires to explain the structure of society, but not reshape it.

As a tool of class war, it lends itself to passive aggression. The danger it poses is that of an insidious plausibility. Instead of worrying over the tangle of deprivation, street culture, teachers' expectations, absent fathers and all the other factors proposed to explain educational failure, why not sit back and let g explain everything?

History informs that question but doesn't settle it. IQ theory considers itself to be science, and it is as science that it has to be evaluated. In this respect, the most telling strand of Murdoch's argument is the one which shows how much the tests themselves are an art rather than a science. Were it not for their history, it might be an art to appreciate. In a more innocent world, children might even enjoy those ingenious little puzzles.

Marek Kohn's 'A Reason for Everything: natural selection and English imagination' is published by Faber & Faber

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