intelligence

intelligence, intelligence testing A well-trampled arena of combat between the advocates of the supremacy of nature and nurture, intelligence is commonly thought of as synonymous with the Intelligence Quotient (IQ), devised originally by Alfred Binet in early twentieth-century France, for the purpose of identifying schoolchildren in need of remedial attention. IQ tests were subsequently developed in the United States into a measure designed to provide a unitary indicator of an individual's innate intelligence. They are standardized around an average of 100 and are calculated separately for men and women.

Many advocates of IQ testing assume that the usual battery of IQ tests combine to produce a measure of intelligence which is genetically transmitted and consequently immutable. Critics argue that the tests were not originally intended to provide a fixed measure of intelligence, unamenable to improvement, and that the assumption that a unitary measure can be provided at all is an unjustifiable reification of a culture-bound concept. Much effort and energy has been invested in this debate, but no convincing conclusions have been evinced in either direction, and estimates of the heritability of IQ still range between zero and 80 per cent. The majority of such estimates are based upon studies of individuals brought up in different environments, whose genetic characteristics are similar or the same (particularly siblings, most often twins). In these circumstances, it is claimed, the factors of inheritance and environment can be separated out, allowing estimates to be made of their respective effects. In reality, It is often very much harder to achieve this, and much criticism of these studies has been directed at the difficulties of ensuring that environments are sufficiently independent to allow such estimates to be made.

There have also been well-publicized accusations that one of the most influential contributors to the debate in the middle years of the century. Sir Cyril Burt, fabricated his results to make it appear that the heritable component accounted for the vast majority (around 80 per cent) of variability in IQ scores. Protagonists include Hans Eysenck, a psychologist who maintains a belief in a high heritable component for IQ, and Leon Kamin, a human geneticist who argues that the debate is unlikely ever to be conclusive, and in any case is misconceived for the reasons given above (see Eysenck and and Kamin , Intelligence: The Battle for the Mind, 1981
). In one analysis which provoked fierce controversy, Arthur R. Jensen (‘How Much Can We Boost IQ and Educational Achievement?’, Harvard Educational Review, 1969)
argued that intelligence is largely explained by genetic factors, and that the poverty of American Blacks was not sufficient to explain away the differences in their test performances in relation to Whites. Critics argued that Jensen's data were unsound and the implications of his study unwarranted.

More recently, the relationship between IQ and social class has also become a focus for renewed academic discussion, after being many years in abeyance. For example, in his critique of the class analysis tradition of research, Peter Saunders starts by pointing to Michael Young's classic definition of a meritocracy in terms of individual rewards for ‘intelligence and effort’, deduces that one might therefore expect research on social mobility to include evidence on these two characteristics, but observes that the question of ability has tended to be overlooked in many studies. For Saunders, measured intelligence is a good indicator of people's abilities, and many studies of class mobility arrive unwarrantably at conclusions about inequality of opportunity because researchers fail to take IQ into account. His own research findings (which are hotly disputed) lead him to conclude that class differentials in educational and occupational attainment might simply be ‘a function of differences in average levels of measured intelligence between the classes’. IQ tests purportedly measure these variations in genetic endowments between different individuals. (The exchanges between Saunders and his critics will be found mainly in the journal Sociology, 1995–7
.)

Similarly, Richard Herrnstein and Charles Murray's controversial account of the relationship between intelligence and both class and race in America (The Bell Curve, 1994) argues that IQ is a good indicator of natural ability, and appears to be a largely inherited trait. Here too, sceptics have replied by assembling no little evidence which casts doubt on both of these propositions, and have concluded that educational attainment and IQ scores are both products, not only of putatively natural or genetic origins, but also of socially determined influences. Most obviously, the results of intelligence tests are (at least in part) a reflection of attributes such as miscellaneous information picked up at home and on television, and of the inclination (mainly instilled by school teaching) to try harder at this particular task than at any other. In other words, test results are partly a function of socialization, substantial aspects of which are already influenced by existing inequalities in the distribution of resources between different classes and ethnic groups. The argument here is that, as John Miner (Intelligence in the United States, 1957) long ago observed, ‘no test item that has ever been devised taps native potential directly, independent of the past life and learning of the respondent’. The most sustained of the many critiques of Herrnstein and Murray's study will be found in Claude S. Fischer et al. , Inequality by Design (1996)
, which argues that social inequalities depend more on social circumstances and the structure of society than they do on IQ, which is itself a social product. In particular, social policies set the ‘rules of the game’ within which individual abilities and effort matter, and it is these that perpetuate the differences between rich and poor.

What is undeniable is that IQ tests have, over their history, been considerably misused in the attempt to prove the inferiority of particular ‘races’, using culturally specific criteria of assessment. It is still not entirely clear that modern tests escape such bias. For this reason it would be imprudent to regard the overall results of these tests as giving a reliable indication of a fixed or innate level of general intelligence. For a comprehensive survey of the literature and issues surrounding intelligence testing see N. Brody , Intelligence (1992
). See also DARWINISM; EUGENICS; HEREDITY.