[Herrnstein and Murray] seem to conclude… that… biological inheritance of IQ… among members of the general society may also explain IQ differences between different racial and ethnic groups…. Such a conclusion goes… much beyond what the facts will support….
[T]he greatest black-white differences are not on the questions which presuppose middle-class vocabulary or experiences, but on abstract questions such as spatial perceptual ability…. [Herrnstein and Murray’s] conclusion that this “phenomenon seems peculiarly concentrated in comparisons of ethnic groups” is simply wrong. When European immigrant groups in the United States scored below the national average on mental tests, they scored lowest on the abstract parts of those tests. So did white mountaineer children in the United States tested back in the early 1930s. So did canal boat children in Britain, and so did rural British children compared to their urban counterparts, at a time before Britain had any significant non-white population. So did Gaelic-speaking children as compared to English-speaking children in the Hebrides Islands. This is neither a racial nor an ethnic peculiarity. It is a characteristic found among low-scoring groups of European as well as African ancestry.
In short, groups outside the cultural mainstream of contemporary Western society tend to do their worst on abstract questions, whatever their race might be….
Perhaps the strongest evidence against a genetic basis for intergroup differences in IQ is that the average level of mental test performance has changed very significantly for whole populations over time and, moreover, particular ethnic groups within the population have changed their relative positions during a period when there was very little intermarriage to change the genetic makeup of these groups….
Perhaps the most dramatic changes were those in the mental test performances of Jews in the United States. The results of World War I mental tests conducted among American soldiers born in Russia–the great majority of whom were Jews–showed such low scores as to cause Carl Brigham, creator of the Scholastic Aptitude Test, to declare that these results “disprove the popular belief that the Jew is highly intelligent.” Within a decade, however, Jews in the United States were scoring above the national average on mental tests, and the data in The Bell Curveindicate that they are now far above the national average in IQ.
Strangely, Herrnstein and Murray refer to “folklore” that “Jews and other immigrant groups were thought to be below average in intelligence. ” It was neither folklore nor anything as subjective as thoughts. It was based on hard data, as hard as any data in The Bell Curve. These groups repeatedly tested below average on the mental tests of the World War I era, both in the army and in civilian life. For Jews, it is clear that later tests showed radically different results–during an era when there was very little intermarriage to change the genetic makeup of American Jews….
Herrnstein and Murray openly acknowledge such rises in IQ….But they seem not to see how crucially it undermines the case for a genetic explanation of interracial IQ differences. They say:
“The national averages have in fact changed by amounts that are comparable to the fifteen or so IQ points separating blacks and whites in America. To put it another way, on the average, whites today differ from whites, say, two generations ago as much as whites today differ from blacks today. Given their size and speed, the shifts in time necessarily have been due more to changes in the environment than to changes in the genes.”
While this open presentation of evidence against the genetic basis of interracial IQ differences is admirable, the failure to draw the logical inference seems puzzling. Blacks today are just as racially different from whites of two generations ago as they are from whites today. Yet the data suggest that the number of questions that blacks answer correctly on IQ tests today is very similar to the number answered correctly by past generations of whites. If race A differs from race B in IQ, and two generations of race A differ from each other by the same amount, where is the logic in suggesting that the IQ differences are even partly racial?
