Intelligence and the social scientist

Public Interest, Summer, 1995 by Leon R. Kass

In contrast, at the bottom, a cognitive underclass is mired in poverty and especially subject to all the social ills that clamor for public attention. In the most impressive part (II) of the book, the authors analyze the relation between cognitive class and social behavior and show that low IQ, even more than low socioeconomic status of one's family of origin, is highly correlated with comparatively high risks of trouble: poverty, dropping out of school, being unemployed or falling altogether out of the labor force, divorce, illegitimate births, welfare dependence, criminal activity, "malparenting," and having children who are also intellectually handicapped. These findings have nothing at all to do with race; the evidence comes from data collected only for non-Hispanic whites.

Later, viewing the American population as a whole, the authors also show that low IQ is especially prevalent among people who have these problems: people from the lowest 20 percent in intelligence (IQ less than 87) account for much or most of the poor (48 percent), the high school dropouts (67 percent), the jailed and imprisoned (62 percent), chronic welfare recipients (57 percent), mothers of illegitimate children (52 percent), mothers of children living in poverty (63 percent), and mothers of children with IQs under 81, the lowest decile (72 percent). The disintegrating American family, often blamed for many of these ills, has crumbled most for people in the lowest cognitive strata.

The data are sobering, the conclusions disquieting, but, to this point, no one could have reason to object. Most people know that intelligence goes a long way in today's world; most readers of this magazine are probably where they are because they were dealt good intellectual equipment, which was then esteemed and cultivated. Most people, if they thought about it, would suspect what Herrnstein and Murray have convincingly shown: very low cognitive ability is a severe handicap in a high-tech world, especially when mores are loosened and when the collapse of families and neighborhoods compel people increasingly to fend for themselves. The Bell Curve also provides evidence to support clearly what any savvy employer already knows: on the job, there is no known substitute for intelligence. A high IQ predicts proficiency of job performance better than any other tested variable, including level of education, interview results, or college grades.

The fuss begins because Herrnstein and Murray also discuss genetics and IQ, the chances of making children smarter by social intervention, and the explosive subject of intellectual differences among racial (they call them "ethnic") groups. They argue, against prevailing public orthodoxy but in accord with most scientific opinion, that general intelligence ("g") is, for individuals, highly heritable - somewhere between 40 percent and 80 percent; they opt for an estimate of 60 percent. (This means, of course, that a sizable portion of cognitive ability depends also on environment and education - who could think otherwise?) They disappoint those who hope to raise cognitive ability in the very dull by arguing that, short of adoption at birth, there is - at least for now - no evidence that altering environment can significantly raise a child's general intellectual ability. And they summarize findings regarding "ethnic groups" that show Asian Americans to be somewhat more intelligent and African Americans significantly less intelligent than non-Hispanic whites.