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.

The reason, which is, admittedly, a difficult one to grasp, is that the contribution of nature is a function of nurture and of nurture a function of nature, the one varying in dependence on the other, so that a statement that might be true in one context of environment and upbringing would not necessarily be true in another. To choose an extreme example: the low-grade mental deficiency known to be associated with a constitutional inability to handle the dietary ingredient phenylalanine is a departure from normality that might be judged simply hereditary in children brought up on a normal diet abundant in the dietary constituent they cannot handle; for phenylketonuria is certainly due to a conjunction of genes that are inherited according to straightforward Mendelian rules.

If however a newborn child with the makeup that would otherwise have made it a victim of phenylketonuria is brought up in a microcosm free from phenylalanine—a difficult and expensive feat—then phenylketonuria would not make itself apparent. In this extreme case therefore a situation can be envisaged in which the disability is wholly environmental in origin. It will manifest itself in the presence of phenylalanine but not in its absence, and will thus present itself as a disease caused by phenylalanine. Alternatively, in a real world abundant in phenylalanine we can confidently describe the departure from normality as genetic in origin.

This example perhaps is too extreme to be informative, so I shall use instead an example which may help to make the point more clearly. The little brackish water shrimp Gammarus chevreuxi is extruded from the brood pouch with red eyes, but usually ends up with black eyes—because of the deposition in them of the black coloring matter melanin. The capacity for forming melanin and the rate at which it is formed and deposited are between them under the control of a number of genetic factors. Coloration of the eye is also affected by a number of other environmental factors: certainly the temperature and probably (though I don’t know for sure) the dietary availability of such substances as tyrosine and phenylalanine or their precursors.

Among these various factors temperature is perhaps the most instructive, for it is possible to choose a genetic makeup such that coloration of the eye will appear to be wholly under environmental control: black at relatively high temperatures of development and reddish or dusky at lower temperatures. It is also possible to choose an ambient temperature at which red eyes or black eyes are inherited as straightforward alternatives according to Mendel’s laws of heredity. Thus to make any pronouncement about the determination of eye color it is necessary to specify both the genetic makeup and the conditions of upbringing: neither alone will do, for the effect of one is a function of the effect of the other. It would therefore make no kind of sense to ask what percentage the coloration of the eye was due to heredity and what percentage was due to environment.

In an earlier paragraph I referred to the extreme likelihood of heredity’s playing some part in the determination of differences of intellectual performance, adding, however, for form’s sake, the qualification “unless intellectual capabilities are unlike all others and human heredity is unlike heredity in all other animals in respect to them.” This possibility I should now like to consider in the light of modern ethological research and our newer philosophic understanding of the character of cultural inheritance in mankind.

Human beings owe their biological supremacy to the possession of a form of inheritance quite unlike that of other animals: exogenetic or exosomatic heredity. In this form of heredity information is transmitted from one generation to the next through non-genetic channels—by word of mouth, by example, and by other forms of indoctrination; in general, by the entire apparatus of culture. I have illustrated this idea3 by pointing out that it was not the making of a wheel that represented a characteristically human activity, but rather the communication from one person to another and therefore from one generation to the next of the knowhow to make a wheel. In this view, Man is not so much a tool-making as a communicating animal. Exogenetic or cultural heredity is that which has made possible the inauguration and retention of the cultural and institutional elements of our current civilization.

Apart from being mediated through nongenetic channels, cultural inheritance is categorically distinguished from biological inheritance by being Lamarckian in character; that is to say, by the fact that what is learned in one generation may become part of the inheritance of the next. This differentiates our characteristically human heredity absolutely from ordinary biological heredity, in which no specific instruction can be imprinted upon the genome in such a way as to become part of the package of inheritance: in ordinary evolution genetic processes are selective and not instructive in character: genetic changes do not arise in response to an organism’s needs and do not, except by accident, gratify them. There is no great mystery about what has made this new pattern of heredity and evolution possible: it has been made possible by the evolution of an organ, the brain, of which the main function is to receive information from the environment to propagate it. In such a system of heredity, indoctrination on the one hand and on the other hand imitation (“aping”) and teachability play crucially important parts—as they are already known to do in the behavior of cats and of apes.

It is very likely therefore that selective forces acting on mankind will have promoted the power of the brain to receive and communicate information, and will have made teachability an endowment of premier importance, so that, while there are likely to be inherited differences of teachability, it is extremely unlikely that teaching and training cannot improve intellectual performances. Indeed, if an intellectual performance were to be totally unaffected by training and practice I should be inclined to think that the wrong performance was being measured. It is because of the embarrassingly foolish belief that an IQ performance measures a person’s “innate intelligence” that extreme hereditarians take the view that IQ is invariant under educative procedures—a claim that reminds one of Francis Galton’s exultant contempt for those who try to raise themselves beyond whatever station in life it may have pleased their genes to call them. 4 If it were indeed true that IQ is variant with age then the only conclusion we could legitimately come to is that the tests upon which its measurement is based are tests of the wrong capacities.

In short, although the possibility of its being so was introduced more as a formal disclaimer than with any other serious purpose, we can conclude that the pattern of inheritance of intellectual differences in human beings is indeed different from the inheritance of other character differences in other animals.

Kamin is “concerned with a single major question: are scores on intelligence tests (IQ’s) heritable?” The answer, he says,

in the consensus view of most intelligence testers, is that about eighty percent of individual variation in IQ scores is genetically determined. This is not a new conclusion. Pearson, writing in 1906, before the widespread use of the IQ test, observed that “the influence of environment is nowhere more than one-fifth that of heredity, and quite possibly not one-tenth of it.” Herrnstein, reviewing the history of intelligence testing to 1971, concluded “We may therefore say that 80 to 85 percent of the variation in IQ amongst whites is due to the genes.”

Kamin goes on to state it as a principal conclusion of his book that: “There exist no data which should lead a prudent man to accept the hypothesis that IQ test scores are in any degree heritable” and then asks how it is that a contrary opinion has so long prevailed among psychologists. Kamin himself believes that socio-political motives underlie the willing assent of IQ psychologists to the notion of inherited differences in intellectual capacities. Indeed, he carries this conspiracy theory of heritability to the point of suggesting that the entire project of IQ psychology is implicitly a great salve for the public conscience and incidentally a great relief to the public purse: if the poor are unsuccessful and inferior because they have been born that way and not because of the way they have been treated, then there is not much we can do about it.

Thus the extreme hereditarian viewpoint is seen as part of that great conspiracy referred to above “to make Nature herself an accomplice in the crime of political inequality.” The conspiracy is not, of course, declared and open, but is rather the subconscious consequence of those economic and class-competitive forces that are thought to shape history. Thus Kamin’s interpretation of the origins of hereditarian theory has about it the kind of Olympian glibness more often found in psychoanalytic theory and it is equally difficult to refute. For just as any criticism of psychoanalysis is construed as an infirmity of the psyche which itself requires psychoanalytic treatment, so criticism of an essentially Marxist theory is thought to reveal its author as yet another victim and dupe of the very socio-economic forces whose efficacy he has presumed to question.

In writing of the pioneers of IQ testing, Kamin makes the useful point, quite new to me, that when Alfred Binet pioneered intelligence testing he described as “brutal pessimism” the belief that the intellectual performance of an individual could not be augmented by special training, and indeed prescribed a therapeutic course in “mental orthopaedics” for those with lowly test scores.

Binet was an agent of the state schooling system in France, and the purpose of his intelligence tests was to identify children in need of special schooling. It was far otherwise with Binet’s American heirs, particularly Lewis M. Terman, who came to regard an intelligence test score as a measure of a fixed quality thought of as “innate intelligence”—an expression still in use and as clearly indicative today as it ever was of a deep-seated misunderstanding of genetics. Moreover, a political, racist, and—in the worst sense of the word—eugenic motivation is made painfully clear by some of Kamin’s quotations from the pioneers of IQ testing. They may not have been the worst offenders: they were writing at a time when it was widely believed that the riotous proliferation of the feeble-minded would repopulate the world with imbeciles, and that affections such as “Mongolism” (Down’s syndrome) represented an atavistic degeneration to a primitive and lowly human type (hence the name).

Nevertheless, the alleged malevolence, racial bias, or even downright dishonesty (see below) of hereditarian psychologists cannot answer the material question whether or not heredity contributes anything to differences of intellectual performance. In denying any such influence, Kamin goes too far—just as H.J. Eysenck went too far in a passage the mere contemplation of which probably now causes him acute embarrassment: “the whole course of development of a child’s intellectual capabilities is largely laid down genetically.”

With thinkers such as Terman to guide them, we need not wonder at how nearly castration became a statutory requirement in a number of American states, nor at how confidently one state legislature or another resolved that heredity played a principal part in crime, idiocy, imbecility, epilepsy, and dependency on charity.

The first tests to reveal that blacks score less highly than whites emerged from the extensive screening undertaken in the First World War, tests of which Kamin dryly remarks that they “appear to have had little practical effect on the outcome of the war.” Such tests have, however, had a profound effect on the relationship between blacks and whites ever since. Another important part of the harvest of the routine screening of recruits was a vast heap of unreliable information on the intelligences of recruits classified by their countries of origin—evidence from which it became pretty clear that northern European countries scored highest, with Mediterraneans, Slavs, and other such lowly types a good way behind. These findings became known in Congress and had an important influence in shaping the US immigration laws.

Madison Grant, in his The Passing of the Great Race, lamented the likelihood that the American people would be irretrievably diminished by the influx of inferior foreigners. With his nice touch for allowing the subjects of his criticism to assassinate themselves, Kamin quotes passages from Grant and a Professor C.C. Brigham of Princeton that sound like a crash course in racism:

The Nordics are…rulers, organizers, and aristocrats…individualistic, self-reliant, and jealous of their personal freedom…as a result they are usually Protestants…. The Alpine race is always and everywhere a race of peasants…. The Alpine is the perfect slave, the ideal serf…the unstable temperament and the lack of coordinating and reasoning power so often found among the Irish…. We have no separate intelligence distributions for the Jews…. Our army sample of immigrants from Russia is at least one half Jewish…. Our figures, then, would rather tend to disprove the popular belief that the Jew is intelligent…he has the head form, stature, and color of his Slavic neighbors. He is an Alpine Slav.

It seems to me that many of the socially disruptive influences that have been drawn from the study of IQ performances are the consequence not so much of the malevolence of those who undertake them as of the inherent failings of IQ testing itself. The illusion that a single number valuation can be attached to anything that an educated man means by the word “intelligence” has already been exposed. But a still graver illusion is even more dangerous because it places foreigners, the poor, and the deprived at a special disadvantage—the illusion that intelligence tests can be devised which are “culture free,” i.e., which are quite uninfluenced by cultural background of the subject’s family, or by the linguistic or performative exercises which he may, or more likely may not, have taken before testing. These naïve beliefs are now passing out of favor, but not before they have done a very great deal of harm.

Where so many hereditarian writers are graceless, rancorous, and inept, Kamin writes with a winning skill that Jonathan Swift would have delighted in. He is merciless to the Californian sickness:

The meek might inherit the kingdom of Heaven, but, if the views of the mental testers predominated, the orphans and tramps and paupers were to inherit no part of California. The California law of 1918 provided that compulsory sterilizations must be approved by a board including “a clinical psychologist holding the degree of Ph.D.” This was eloquent testimony to Professor Terman’s influence in his home state.

These passages of fine polemical writing must not be allowed to distract attention from the most important part of Kamin’s book, his critique of observations purporting to demonstrate a very high degree of heritability of differences in IQ scores. Because it has been the subject of some searching investigative journalism by the Sunday Times in London, we shall pay particular attention to the testing of twins.

Kamin gives an admirably lucid account of the methodology of twin studies, of which the underlying principle is this: twins may be of the kind called identical, i.e., the product of a single fertilized egg, or they may be “fraternal,” i.e., litter mates—who resemble each other genetically no more closely than ordinary brothers and sisters. Identical twins can be assumed fairly confidently to have the same genetic makeup. Identical twins who have been separated and brought up in different environments are methodologically a godsend. The degree of correlation between their measured intellectual performances is an estimate of the degree to which heredity has contributed to them, provided the various environments are representative of the whole range of environments to which human beings are exposed, and twins themselves are representative of the entire population of which they are members.

However, as Kamin writes, “there is little reason to suppose that these assumptions hold in any of the studies that have been made of separated twins.” Kamin pays special attention to the studies made by Professor Cyril Burt, one of the great pioneers of educational psychology and professor of psychology at one of England’s three leading universities: University College, London. Burt’s direct influence was probably, largely, a harmful one; because of his advocacy and the tendency to regard his opinions as Holy Writ, eleven-year-olds in Great Britain were subjected to tests intended to divide the bright from the comparatively dull. Indirectly his teachings may be said to have invited the backlash which has led now to the re-institution of those comprehensive schools that are founded on the proposition that all children are fundamentally of equal ability—so making the usual confusion between the fact of biological inequality and the political right to equal treatment. Still, he can hardly be blamed if, for political reasons, his teachings have now had the effect of handicapping those very children whose interests they were designed to promote.

Kamin’s criticisms of Burt make some of the most damaging accusations that can ever have been leveled against a scholar:

…the various papers published by Burt often contain mutually contradictory data, purportedly derived from the same study. These contradictions, however, are more than compensated for by some remarkable consistencies which occur repeatedly in his published works. The first examples that we shall cite do not involve his study of separated twins, but later examples will do so.

The papers of Professor Burt, it must be reported, are often remarkably lacking in precise descriptions of the procedures and methods that he employed in his IQ testing. The first major summary of his kinship studies, a 1943 paper, presents a large number of IQ correlations, but virtually nothing is said of when or to whom test were administered, or of what tests were employed. The reader is told, “Some of the inquiries have been published in LCC reports or elsewhere; but the majority remain buried in typed memoranda or degree theses.”

Toward the end of 1976 a furor was started by the publication in the London Sunday Times of an article by a team of investigative journalists led by Dr. Oliver J. Gillie, their medical correspondent and a gifted geneticist. The investigations questioned the probity of Burt’s entire work, raising a number of awkward questions to which no satisfactory answers had then been given. In addition, Professor Jack Tizard, the highly respected professor of child development in London University, delivered a lecture likening the revelations about Burt to those which disclosed the forgery of the Piltdown skull. Tizard said his suspicions had been aroused two and one half years beforehand by his complete failure to find two people at University College who were said to have worked very closely with Burt in his research—colleagues with whom he had, indeed, published a number of papers between 1952 and 1959—Miss Howard and Miss Conway.

The Sunday Times team fared no better; they could find no record that either had ever been on the staff of the Psychology Department at the University College, and could not even trace them in the files at Senate House, reputedly the central nervous system of the University of London, which holds duplicates of the documents of the University’s constituent colleges.

Direct inquiries to 18 people who knew Burt and his circle well from the 1920s, when he was at the National Institute of Industrial Psychology, until he died, has failed to find anyone who met Howard or Conway or knew of them, and no one with these names is listed in the files of the British Psychological Society.

The Sunday Times concluded its investigation by proposing the hypothesis that Misses Howard and Conway never existed.

However, in spite of these misgivings there seems no doubt that Margaret Howard anyway did “in some real sense” (as philosophers say) exist. Professor John Cohen of Manchester University is quoted by Dr. Gillie as saying that he knew Miss Howard well. In the follow-up article containing this revelation he also quotes a damaging accusation by Professor and Mrs. Clarke of Hull University that articles which they did not write were published in their name by Sir Cyril Burt, and they add, “It is extremely difficult to see how Burt arrived at some of his figures on inheritance of intelligence without cooking them.”

Kamin’s evidence and the Sunday Times investigations point to Burt’s having a fairly lofty attitude toward the provenance and probity of his empirical data. Indeed, the accusation that Burt’s findings were too good to be true—i.e., were too closely in line with theoretical anticipations—give us a clue to the most puzzling question of all about Burt: why, why did he act deviously?

The only explanation I can think of is that a belief in the predominant influence of heredity in relation to intellectual performances has the same kind of appeal for those who hold it as Lamarckism—the belief in an inherence of acquired characters—has had for unskilled biologists. It seems to them so right, so obviously and necessarily true, so clearly in keeping with their sense of the fitness of things that people who do not share their beliefs must somehow be persuaded in their own best interests to do so, if necessary by a slight adjustment of the figures here, an assumption based upon a lifetime of experience there, and judicious selection of data somewhere else. Fraudulent experiments have been used to uphold Larmarckian interpretations of heredity, and in Burt’s methodological malpractices we may have another case in point. Villainy is not explanation enough: Burt probably thought of himself as the evangel of a Great New Truth.

So much anyway for the case for the prosecution. The most significant utterance in the case for the defense is that of Professor Eysenck himself, a dedicated hereditarian. In a letter in the Sunday Times citing Burt’s data and calculations he concedes that some of his procedures were “of course inadmissible” to a degree “that makes it impossible to rely on these figures in the future.”5 On the other hand Professor A.R. Jensen, joining in the Times debate, did not share Eysenck’s view that any of Burt’s procedures were inadmissible: he dismisses the attack on Burt as so much calumny and concludes, with the “complete confidence” which natural scientists so seldom feel “…that, even if all of Burt’s findings were thrown out entirely, the picture regarding the heritability of IQ would not be materially changed.” I am quite sure Jensen is not intending to be ironical; but this judgment does seem to be a rather strange compliment to a man thought of as a founding father of psychometry.

There is, as a matter of fact, a well-established precedent for the selection or adjustment of figures to fit a preconceived hypothesis: R.A. Fisher, at that time the world’s foremost authority on small sample statistics, once pointed out that Mendel’s famous segregation ratios (3:1; 9:3:3:1;) were numerically much too good to be true. Given the size of his samples, no such degree of conformity to theoretical anticipation could be judged plausible. Whatever R.A. Fisher’s motives may have been in calling attention to this fact, we may be quite sure it was not his intention to show Mendel up as running dog of Fascism (as the faithful later came to call him). The most plausible explanation seems to be that the abbé’s gardeners and assistants had formed a pretty clear idea of what ratio Mendel was expecting and whether out of loyalty or affection supplied their reverend employer with results they thought he would like to hear.

There is, however, a profoundly important difference between the cases of Mendel and of Burt: Mendel was right.

Now that the IQ controversy has risen to a new height and shows no sign of abating, the publication of Block’s and Dworkin’s The IQ Controversy is particularly timely and valuable. It is in the genre known as a “reader,” that is to say it gives us a conspectus of prevailing opinions in the words of those who hold them. The danger of a reader in such a context as this is that the editor may, by judicious selection or omission, prejudice the conclusions that an impartial reader might come to. Block and Dworkin have not done this: their editorial matter provides only that minimum of connective tissue which a book such as this urgently needs. It is also fair to point out that the only way in which the hereditarians could be rescued completely from public obloquy would be by omitting their contributions altogether. Block and Dworkin have rightly decided against so partial a procedure: they play fair, though it might be thought cruel to republish the controversy between Walter Lippmann and Lewis Terman, published in the New Republic in 1922 and 1923. This gives one the sick feeling that people of sensibility have when they first witness a bullfight: the contest is so cruelly unequal when one contestant has nothing but a slow-footed and ponderous irony with which to defend himself against the highly intelligent, light-footed, and cruelly provocative Mr. Lippmann.

A special strength of their book—and one that enormously enhances its value for college reading—is their generous allocation of space to such real professionals as Richard Lewontin and John Thoday, with a passing quotation from Michael Lerner. In the course of a grave, learned, and witty investigation of what has come to be called “Jensenism,” Lewontin remarks:

There is no such thing as the heritability of IQ, since heritability of a trait is different in different populations at different times. Second, the data on which the estimate of 80% for Caucasian populations is based, are themselves of very doubtful status.

The citation from Michael Lerner includes this sentence:

…it is a fact that generations of discrimination have made direct comparisons of mental traits between Negroes and whites not biologically meaningful.

John Thoday expounds clearly and critically the methodology of intragroup and between-group comparisons, calling attention, as he does so, to blunders by IQ psychologists of a kind that disclose a truly deep-seated misunderstanding of genetic principles. He concludes that:

…there is no evidence which reveals whether the Negro-white IQ difference has any genetic component or any environmental component….

The reflection that might well be in the forefront of the minds of laymen as they put down the Block and Dworkin book is this: the question of the heritability of differences of IQ is one upon which everybody feels entitled to have an opinion. In recent years even a prominent electrician has felt authoritative enough to have his say; yet on matters to do with heritability it might be thought prudent to give most weight to the opinions of geneticists. Why, then, is it that some of the world’s most prominent geneticists—among them Michael Lerner, Richard Lewontin, Walter Bodmer, and John Thoday—remain so deeply unconvinced by the hereditarian arguments of such as Jensen and Eysenck? We need not resort to murky ideological explanations to find the reason. It is more likely, I suggest, that at a time of deeply troubled race relations, when the whole possibility of peaceful coexistence and mutual respect in multi-racial communities is in question in many parts of the world, these geneticists feel an imperatively urgent desire to put the scientific record straight.

This Issue

February 3, 1977