The Science and Politics of IQ
The IQ Controversy
If a broad line of demarcation is drawn between the natural sciences and what can only be described as the unnatural sciences, it will at once be recognized as a distinguishing mark of the latter that their practitioners try most painstakingly to imitate what they believe—quite wrongly, alas for them—to be the distinctive manners and observances of the natural sciences. Among these are:
(a) the belief that measurement and numeration are intrinsically praiseworthy activities (the worship, indeed, of what Ernst Gombrich calls idola quantitatis);
(b) the whole discredited farrago of inductivism—especially the belief that facts are prior to ideas and that a sufficiently voluminous compilation of facts can be processed by a calculus of discovery in such a way as to yield general principles and natural-seeming laws;
(c) another distinguishing mark of unnatural scientists is their faith in the efficacy of statistical formulas, particularly when processed by a computer—the use of which is in itself interpreted as a mark of scientific manhood. There is no need to cause offense by specifying the unnatural sciences, for their practitioners will recognize themselves easily: the shoe belongs where it fits.
The objections of the educated to IQ psychology arise from several sets of causes: first, misgivings about whether it is indeed possible to attach a single-number valuation to an endowment as complex and as various as intelligence; second, a biologically well-founded feeling of repugnance to the notion that differences of intelligence are to so high a degree under genetic control that all the apparatus of pedagogy and special training is necessarily relegated to an altogether minor role. To these have recently been added a third, some grave doubts about the probity of Cyril Burt’s investigations of intelligence quotients in twins—researches which led him to conclusions which have had a profound and by no means wholly beneficent effect on educational theory and practice. Burt’s work has been the subject of extensive correspondence and annotation in both the London Times and the Sunday Times.
We must consider first the illusion embodied in the ambition to attach a single number valuation to complex quantities—a problem that has vexed demographers in the past, and also soil physicists—as Dr. J.R. Philip, FRS, has pointed out.1 It bothers economists, too.
Although the more disputative IQ psychologists give the impression of being incapable of learning anything from anybody, it seems only fair to give them a chance not to persist in the errors of judgment that have been avoided in so many other areas of learning. Let us discuss the single number valuation of complex variables in a number of different contexts.
First, demography. In the days when it was believed that the people of the Western world were dying out through infertility, it was thought an obligation upon demographers to devise a single value measure of a nation’s reproductive prowess and future population prospects. Kuczynski accordingly offered up his “net reproduction rate” and R.A. Fisher and A.J. Lotka the “Malthusian parameter” or “true rate of natural increase.” Both had their adherents and confident predictions were based on both, but the predictions were mistaken and today no serious demographer believes that a single number valuation of reproductive vitality is feasible: reproductive vitality depends on altogether too many variables, not all of which are “scalar” in character. Among them are the proportions of married and of unmarried mothers, the prevailing fashions relating to marriage ages, family numbers, and the pattern of family building, the prevailing economic and fiscal incentives or disincentives to procreation, and the availability and social acceptability of methods of birth control. It is no wonder that the single number valuations of reproductive vitality have fallen out of use. Modern demographers now go about their population projections in a biologically much more realistic way, basing them essentially upon the sizes of completed families and the analysis of “cohorts”—groups of people born or married in one specific year.
Somewhat similar considerations apply to the attempt to epitomize in a single figure the field behavior of a soil. The physical properties and field behavior of soil depend upon particle size and shape, porosity, hydrogen iron concentration, material flora, and water content and hygroscopy. No single figure can embody itself in a constellation of values of all these variables in any single real instance.
Rather similar considerations apply to the way some economists use the notion of GNP (“the tribal God of the Western world”). GNP as such may be an unexceptionable idea, but there has been an increasing tendency to use the growth rate of GNP, positive or negative, as a measure of national welfare, well-being, and almost of moral stature. Any such use is, of course, totally inadmissible: how can a single figure embody in itself a valuation of a nation’s confidence in itself, its practical concern for the welfare of its citizens, the stability of its institutions, the safety of its streets, and other such non-scalar and therefore presumably unscientific variables.
IQ psychologists would nevertheless like us to believe that such considerations as these do not apply to them; they like to think that intelligence can be measured as if it were indeed a simple scalar quantity. I recall in particular the barefaced impudence with which a notorious IQ psychologist has proposed that a person’s IQ is his intelligence as much as his height might be five feet and five inches. Unhappily for them, this is not so. If IQ psychologists were merely playing an academic game that did not affect the rest of us for good or ill, they would of course be entitled to define intelligence in any way they wished, but for the educated, “strength of understanding,” as Jane Austen described it, is a complicated and manysided business. Among its elements are speed and span of grasp, the ability to see implications and conversely to discern non sequiturs and other fallacies, the ability to discern analogies and formal parallels between outwardly dissimilar phenomena or thought structures, and much else besides. One number will not do for all these, even if—to take what must surely be one of the most abject of arguments put forward by IQ psychologists in favor of single value mensuration—a child’s IQ score is positively correlated with his income in later years.
To turn now to the vexed problem of the heritability of intellectual differences, it may be said with some confidence that unless intellectual abilities are unlike all others and unless human beings are unlike all other animals in respect to possessing them—two suppositions that are by no means as farfetched as we may at first incline to think them (see below)—then intellectual differences are indeed genetically influenced. This applies even if upbringing and indoctrination are of preponderant importance: for here we should certainly expect inherited differences in teachability and the ability to profit by experience.
The subject is bedeviled more than any other by the tendency of disputants to spring into political postures which allow them no freedom of movement. Thus it is a canon of high tory philosophy that a man’s breeding—his genetic makeup—determines absolutely his abilities, his destiny, and his deserts; and it is no less characteristic of Marxism that, men being born equal, a man is what his environment and his upbringing make of him. The former belief lies at the root of racism, fascism, and all other attempts to “make nature herself an accomplice in the crime of political inequality” (Condorcet) and the latter founders on the fallacy of human genetic equality (“A strange belief,” said J.B.S. Haldane—a longtime member of the CP).
Confronted with this dilemma, modern liberals are keenly aware that, not so very long ago, there were countries in which those who questioned the dogma of genetic elitism would have been trampled down by big boots; but they have been slow—as liberals sometimes are—to realize that today it is the other way about: those whose views conflict with the dogma of equality are vilified, shouted down, and rebutted by calumnies. Human geneticists are particularly vulnerable to the vilification of doctrinaire Marxists because, as scientists, they are in thrall to such bourgeois superstitions as the desirability of telling the truth. Among the latest victims of such vilification are the human geneticists engaged in human karyotype screening, which entails the investigation of the human chromosome makeup at birth or earlier, to identify in good time such abnormalities as are now known to be associated with Down’s syndrome (“Mongolism”), a number of disorders of sexual development (e.g., Turner’s syndrome, Klinefelter’s syndrome), and sometimes grave personality disorders, particularly that which is associated with the human sex chromosome makeup symbolized as 47XYY. The president of the American Society of Human Genetics, Dr. John L. Hamerton, delivered a wise and temperate address on the problems raised by karyotype screening at the annual meeting of the society in Baltimore in 1975.2
Chromosomal abnormalities are unfortunately irremediable, but this is not to say that, with advance warning, their physical and behavioral consequences cannot be the subject of meliorative or preventive intervention. Nevertheless, malevolent intentions are taken for granted by disputants claiming to speak—as they all do—for “the people,” so that over and above the usual braying noises of protest that invariably accompany any attempt to conduct a census, karyotypers are exposed to shrill accusations of “genetic McCarthyism” while the rest of us are warned of “much more serious eugenic implications” to create the impression that human geneticists are busily planning to refuel the gas chambers.
It is characteristic of the reasoning that human geneticists have to contend with that their opponents, with no apparent awareness of inconsistency, simultaneously deny the association of behavioral defects with the XYY makeup and suggest an alternative explanation of it. The alternative explanation is that, so far from being a cause of behavioral abnormalities, the XYY chromosome defect is itself a marker of upbringing in a deprived or underprivileged environment—a misfortune of which abnormal behavior is a collateral manifestation. No feat of reasoning can however conceal from us the realization that the real crime of human geneticists, in the opinion of self-appointed spokesmen for “the people,” is to have provided evidence of inborn human inequality.
In voluminous correspondence in the London Times about Cyril Burt’s methods, several distinct arguments were going on simultaneously. The professionals were talking about whether or not it is possible to attach an exact figure to the contribution of heredity to differences of human intelligence, and the laymen were asking themselves whether there is any heritable element or not. In the latter discussion the pedigrees of the Bach and the Bernoulli families were brandished against familiar evidence of gifted children being born of very ordinary parents. The really important question however is whether or not it is possible to attach exact percentage figures to the contributions of nature and nurture (Shakespeare’s terminology) to differences of intellectual capacity. In my opinion it is not possible to do so, for reasons that seem to be beyond the comprehension of IQ psychologists, though they were made clear enough by J.B.S. Haldane and Lancelot Hogben on more than one occasion, and have been made clear since by a number of the world’s foremost geneticists.
"Fifty Years' Progression in Soil Physics," Geoderma, 12, pp. 265-280, 1974.↩
American Journal of Human Genetics 28, pp. 107-122, 1976.↩