Discussion: (0 comments)
There are no comments available.
A public policy blog from AEI
The Bell Curve
View related content: Society and Culture
In April, I recorded an interview of almost two and a half hours with Sam Harris for his Waking Up podcast which, I learned only after I had done it, regularly attracts a few million listeners. We spent more than half of the interview discussing what is actually in “The Bell Curve” as opposed to what people think is in it. Both of us expected our Twitter feeds to light up with nasty reactions after the interview was posted. But the opposite happened. The nasty reactions were far outnumbered by people who said they had always assumed that “The Bell Curve” was the hateful pseudoscientific mess that the critics had claimed, but had now decided they wanted to give the book a chance. It has been a heartening experience.
However, there is a difficulty with giving “The Bell Curve” a chance. The paperback edition has 26 pages of front material, 552 pages of main text, a 23-page response to the critics, 111 pages of appendixes, another 111 pages of endnotes, and a 58-page bibliography. It’s a lot to get through. But there’s a shorter way to get a good idea of what’s in the book: Dick Herrnstein and I began each chapter with a summary that was usually about a page long. With the publisher’s permission, I have stitched all of those summaries together, along with selections from the Introduction and the openings to each of the four parts of the book. If these tidbits arouse enough interest that you buy the book, I will be delighted. But at this point in my life, my main objective is that a labor of love, written with a friend who I still miss twenty-three years after his death, be seen for what it is.
No alterations have been made in the published text. I have interspersed a few bits of explanatory text that are italicized and enclosed by brackets. Look for more chapter summaries in the coming days. For the Introduction, follow this link. For Part I, follow this one, Part II, this one. To view all four parts together, please visit our The Bell Curve, explained spotlight page.
The National Context
Part II was circumscribed, taking on social behaviors one at a time, focusing on causal roles, with the analysis restricted to whites wherever the data permitted. We now turn to the national scene. This means considering all races and ethnic groups, which leads to the most controversial issues we will discuss: ethnic differences in cognitive ability and social behavior, the effects of fertility patterns on the distribution of intelligence, and the overall relationship of low cognitive ability to what has become known as the underclass. As we begin, perhaps a pact is appropriate. The facts about these topics are not only controversial but exceedingly complex. For our part, we will undertake to confront all the tough questions squarely. We ask that you read carefully.
Chapter 13. Ethnic Differences in Cognitive Ability
Despite the forbidding air that envelops the topic, ethnic differences in cognitive ability are neither surprising nor in doubt. Large human populations differ in many ways, both cultural and biological. It is not surprising that they might differ at least slightly in their cognitive characteristics. That they do is confirmed by the data on ethnic differences in cognitive ability from around the world. One message of this chapter is that such differences are real and have consequences. Another is that the facts are not as alarming as many people seem to fear.
East Asians (e.g., Chinese, Japanese), whether in America or in Asia, typically earn higher scores on intelligence and achievement tests than white Americans. The precise size of their advantage is unclear; estimates range from just a few to ten points. A more certain difference between the races is that East Asians have higher nonverbal intelligence than whites while being equal, or perhaps slightly lower, in verbal intelligence.
One message of this chapter is that such differences are real and have consequences. Another is that the facts are not as alarming as many people seem to fear.
The difference in test scores between African-Americans and European-Americans as measured in dozens of reputable studies has converged on approximately a one standard deviation difference for several decades. Translated into centiles, this means that the average white person tests higher than about 84 percent of the population of blacks and that the average black person tests higher than about 16 percent of the population of whites.
The average black and white differ in IQ at every level of socioeconomic status (SES), but they differ more at high levels of SES than at low levels. Attempts to explain the difference in terms of test bias have failed. The tests have approximately equal predictive force for whites and blacks. In the past few decades, the gap between blacks and whites narrowed by perhaps three IQ points. The narrowing appears to have been mainly caused by a shrinking number of very low scores in the black population rather than an increasing number of high scores. Improvements in the economic circumstances of blacks, in the quality of the schools they attend, in better public health, and perhaps also diminishing racism may be narrowing the gap.
The debate about whether and how much genes and environment have to do with ethnic differences remains unresolved. The universality of the contrast in nonverbal and verbal skills between East Asians and European whites suggests, without quite proving, genetic roots. Another line of evidence pointing toward a genetic factor in cognitive ethnic differences is that blacks and whites differ most on the tests that are the best measures of g, or general intelligence. On the other hand, the scores on even highly g-loaded tests can be influenced to some extent by changing environmental factors over the course of a decade or less. Beyond that, some social scientists have challenged the premise that intelligence tests have the same meaning for people who live in different cultural settings or whose forebears had very different histories.
Open and informed discussion is the one certain way to protect society from the dangers of one extreme view or the other.
Nothing seems more fearsome to many commentators than the possibility that ethnic and race differences have any genetic component at all. This belief is a fundamental error. Even if the differences between races were entirely genetic (which they surely are not), it should make no practical difference in how individuals deal with each other. The real danger is that the elite wisdom on ethnic differences—that such differences cannot exist—will shift to opposite and equally unjustified extremes. Open and informed discussion is the one certain way to protect society from the dangers of one extreme view or the other.
Chapter 14. Ethnic Inequalities in Relation to IQ
Ethnic differences in education, occupations, poverty, unemployment, illegitimacy, crime, and other signs of inequality preoccupy scholars and thoughtful citizens. In this chapter, we examine these differences after cognitive ability is taken into account.
We find that Latinos and whites of similar cognitive ability have similar social behavior and economic outcomes. Some differences remain, and a few are substantial, but the overall pattern is similarity. For blacks and whites, the story is more complicated. On two vital indicators of success—educational attainment and entry into prestigious occupations—the black-white discrepancy reverses. After controlling for IQ, larger numbers of blacks than whites graduate from college and enter the professions. On a third important indicator of success, wages, the black-white difference for year-round workers shrinks from several thousand to a few hundred dollars.
In contrast, the B/W gap in annual family income or in persons below the poverty line narrows after controlling for IQ but still remains sizable. Similarly, differences in unemployment, labor force participation, marriage, and illegitimacy get smaller but remain significant after extracting the effect of IQ. These inequalities must be explained by other factors in American life. Scholars have advanced many such explanations; we will not try to adjudicate among them here, except to suggest that in trying to understand the cultural, social, and economic sources of these differences, understanding how cognitive ability plays into the mix of factors seems indispensable. The role of cognitive ability has seldom been considered in the past. Doing so in future research could clarify issues and focus attention on the factors that are actually producing the more troubling inequalities.
Chapter 15. The Demography of Intelligence
When people die, they are not replaced one for one by babies who will develop identical IQs. If the new babies grow up to have systematically higher or lower IQs than the people who die, the national distribution of intelligence changes. Mounting evidence indicates that demographic trends are exerting downward pressure on the distribution of cognitive ability in the United States and that the pressures are strong enough to have social consequences.
Throughout the West, modernization has brought falling birth rates. The rates fall faster for educated women than the uneducated. Because education is so closely linked with cognitive ability, this tends to produce a dysgenic effect, or a downward shift in the ability distribution. Furthermore, education leads women to have their babies later—which alone also produces additional dysgenic pressures.
Putting the pieces together, something worth worrying about is happening to the cognitive capital of the country. Improved health, education, and childhood interventions may hide the demographic effects, but that does not reduce their importance.
The professional consensus is that the United States has experienced dysgenic pressures throughout either most of the century (the optimists) or all of the century (the pessimists). Women of all races and ethnic groups follow this pattern in similar fashion. There is some evidence that blacks and Latinos are experiencing even more severe dysgenic pressures than whites, which could lead to further divergence between whites and other groups in future generations. The rules that currently govern immigration provide the other major source of dysgenic pressure. It appears that the mean IQ of immigrants in the 1980s works out to about 95. The low IQ may not be a problem; in the past, immigrants have sometimes shown large increases on such measures. But other evidence indicates that the self-selection process that used to attract the classic American immigrant—brave, hardworking, imaginative, self-starting, and often of high IQ—has been changing, and with it the nature of some of the immigrant population.
Putting the pieces together, something worth worrying about is happening to the cognitive capital of the country. Improved health, education, and childhood interventions may hide the demographic effects, but that does not reduce their importance. Whatever good things we can accomplish with changes in the environment would be that much more effective if they did not have to fight a demographic head wind.
Chapter 16. Social Behavior and the Prevalence of Low Cognitive Ability
In this chapter, the question is not whether low cognitive ability causes social problems but the prevalence of low cognitive ability among people who have those problems. It is an important distinction. Causal relationships are complex and hard to establish definitely. The measure of prevalence is more straightforward. For most of the worst social problems of our time, the people who have the problem are heavily concentrated in the lower portion of the cognitive ability distribution. Any practical solution must therefore be capable of succeeding with such people.
From THE BELL CURVE by Richard J. Herrnstein and Charles Murray. Copyright 1994 by Richard J. Herrnstein and Charles Murray. Reprinted by permission of Free Press, an imprint of Simon & Schuster, Inc. All rights reserved.
There are no comments available.
1789 Massachusetts Avenue, NW, Washington, DC 20036
© 2017 American Enterprise Institute