Unnatural Science, cont’d.

To the Editors:

I should like to add a number of footnotes to my article “Unnatural Science” (February 3, 1977) which may go some way toward meeting criticisms in letters which have been sent directly to me or for which The Review has unfortunately been unable to find space.

1. The question of the single-number valuation of IQ. Several correspondents have spelled it out to me that both athletic prowess and a human being’s body temperature, for example, are influenced by a host of variables; yet an athlete’s performance in the hundred-yard dash and a patient’s temperature are both recorded in single values on one-dimensional scales. This is very true, but a patient’s temperature is not taken by any physician to measure his state of health, nor is an athlete’s speed in the hundred-yard dash used as a measure of athleticism or any other physical analogue of intelligence. The one measures a patient’s body temperature only, and the other how long a man takes to run a hundred yards in a hurry. In just the same way an IQ test measures a candidate’s prowess at the particular, kinds of intellections which are measured by such tests.

2. Although Burt’s twin studies are agreed to be flawed and in some ways suspicious, other such studies have borne out his general conclusions. But here I must sound a note of caution. In medical science generally, in spite of the fact that it deals with problems intrinsically simpler than those that confront the psychologist, the most elaborate precautions (“double-blind” trials and the like) are always taken to prevent even the most objective-seeming trials from being biased by the prejudices or inclinations of experimentalists. The most high-minded and incorruptible medical men fall in with the drill of these trials because they know how fatally easy it is to deceive themselves. Do psychologists know as much? Burt’s admitted peccadilloes cast a shadow of doubt over all similar investigations.

3. Some correspondents believe I was quite mistaken to say that an extreme hereditarian view relegates “the apparatus of pedagogy and special training” to a minor role. I refer those who take this view to Francis Galton’s exultantly contemptuous dismissal of those who aim higher in life than their hereditary endowment justifies, and also to pp. 144-151 of Eysenck’s The Inequality of Man in which I seem to detect something of the same spirit, especially with reference to the activities of the Office of Economic Opportunity.

4. I was accused of having unfairly depreciated the value of IQ scores in predicting scholastic performance and success in later life. Unfortunately, it seems not to be realized that there is a fundamental asymmetry in assessing the results of IQ tests or, indeed, of examinations of any other kind. We all know of children who, though they did badly in exams at school or got bad IQ test marks, went on to do very well, even in academic pursuits. But what about the children who did badly in exams, got low IQ scores, and then failed because they did so? These unfortunates have dropped from sight: die im Dunkeln sieht man nicht, Brecht says.

5. An anecdote about wicked old Sir Francis Galton will illustrate very clearly the difference between an IQ score and intelligence. Lewis Terman, God alone knows how, estimated Galton’s IQ as 200—a figure of which he said that it was not equaled by more than one child in 50,000 of the generality—but at the same time we know from Galton’s own memoirs that when at age eight he was issued with Caesar’s Commentaries for class use he was vastly surprised to find his copy so new-looking and shiny, considering that, having been written by Caesar, it must be getting on for 2,000 years old. Yet is it not absurd to ask oneself—as strictly speaking one should if one is to acquiesce in the illusion of single-value mensuration—how much must be deducted from an IQ score of 200 to make allowance for so egregious a mistake?

Peter Medawar

Harrow, England