James Q. Wilson, National Review, December 5, 1994.

Excerpt:

Serious readers will ask four main questions about The Bell Curve. Is it true that intelligence explains so much behavior? How can IQ produce this effect? If it does, is there anything we should do differently in public policy? And will this nexus affect race relations?

My answer to the first question is unequivocally yes. I first became aware of the significance of low IQ as a predictor of ordinary criminality when I collaborated with the late Richard Herrnstein in writing Crime and Human Nature. Since we published that book in 1985, evidence showing that delinquents and other offenders have a lower measured intelligence, especially on the verbal component of the tests, has continued to accumulate. Now Herrnstein and Murray have shown that there are strong correlations between IQ and occupation level, school attainment, worker productivity, and possibly even political participation. These correlations exist within a given racial group (say, whites) and after matching people on the basis of their social class. (Controlling for social class means that the IQ—outcome link is even stronger than many of The Bell Curve‘s graphs reveal, since IQ also partially determines a person’s social class.) Herrnstein and Murray present their evidence abundantly, cautiously, and in painstaking detail. Though quibbles are possible, I find it very unlikely that their answers to this question will be confuted.

The second question seems to present a tougher challenge. How can IQ affect things that don’t seem to involve much thinking, like stealing a radio, conceiving a child out of wedlock, or doing a poor job as a bricklayer? The answer, I think, is that even the simplest tasks require the mind to recall and process an enormous amount of information; even the most powerful temptations evoke from us very different degrees of vividness in imagining future consequences. We forget this when we adopt the language of “instinct,” “social forces,” “economic incentives.” Though all of these factors are important, all are mediated by the human mind in complex ways. On average, bright people are more likely than not-so-bright ones to recall past experiences and use them to shape present actions, to foresee vividly the future consequences of actions, and to internalize rules of thumb for everything from how to lay a straight line of bricks to how to prevent an unwanted pregnancy. There are many exceptions—bright people who give way to every temptation, not-so-bright people who follow the Ten Commandments scrupulously. But on average, IQ makes a difference across a wide range of human behaviors. How wide a range we have yet to learn.

My answer to the third question is, “It depends.” To be exact, the public-policy implications depend on two things. One is how much of the variance in unhappy conditions—criminality, poverty, low worker productivity, and the like—can be explained by differences in intelligence. We know with certainty that IQ cannot explain all of the variance, because rates of crime, poverty, and illegitimacy change dramatically without corresponding changes in intelligence. But even allowing for these changes, the statistical techniques that Herrnstein and Murray use do not, for technical reasons, permit a good estimate of how much of the difference between two groups (say, white women on welfare and white women not on welfare) can be attributed to IQ differences.

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