'The Bell Curve', Explained: Part 1, the Emergence of a Cognitive Elite (2024)

In April, I recorded an interview of almost two and a half hours with Sam Harris for his Waking Up podcastwhich, 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 summariesin the coming days. For the Introduction, follow this link. To view all four parts together, please visit our The Bell Curve, explainedspotlight page.

Part I

The Emergence of a Cognitive Elite

The twentieth century dawned on a world segregated into social classes defined in terms of money, power, and status. The ancient lines of separation based on hereditary rank were being erased, replaced by a more complicated set of overlapping lines. Social standing still played a major role, if less often accompanied by a sword or tiara, but so did out-and-out wealth, educational credentials, and, increasingly, talent.

Our thesis is that the twentieth century has continued the transformation, so that the twenty-first will open on a world in which cognitive ability is the decisive dividing force. The shift is more subtle than the previous one but more momentous. Social class remains the vehicle of social life, but intelligence now pulls the train.
Our thesis is that the twentieth century has continued the transformation, so that the twenty-first will open on a world in which cognitive ability is the decisive dividing force. The shift is more subtle than the previous one but more momentous. Social class remains the vehicle of social life, but intelligence now pulls the train.

Cognitive stratification takes different forms at the top and the bottom of the scale of intelligence. Part II will look at the bottom. In Part I, we look at the top. Its story line is that modern societies identify the brightest youths with ever increasing efficiency and then guide them into fairly narrow educational and occupational channels. These channels are increasingly lucrative and influential, leading to the development of a distinct stratum in the social hierarchy, which we hereby dub the Cognitive Elite. The isolation of the brightest from the rest of society is already extreme; the forces driving it are growing stronger rather than weaker. Governments can influence these forces but cannot neutralize them.

This does not mean that a member of the cognitive elite never crosses paths with a person with a low IQ, but the encounters that matter tend to be limited. The more intimate or more enduring the human relationship is, the more likely it is to be among people similar in intellectual level. That the brightest are identified has its benefits. That they become so isolated and inbred has its costs. Some of these costs are already visible in American society, while others lie over the horizon.

Chapter 1. Cognitive Class and Education, 1900–1990

In the course of the twentieth century, America opened the doors of its colleges wider than any previous generation of Americans, or other society in history, could have imagined possible. This democratization of higher education has raised new barriers between people that may prove to be more divisive and intractable than the old ones.

The growth in the proportion of people getting college degrees is the most obvious result, with a fifteen-fold increase from 1900 to 1990. Even more important, the students going to college were being selected ever more efficiently for their high 1Q. The crucial decade was the 1950s, when the percentage of top students who went to college rose by more than it had in the preceding three decades. By the beginning of the 1990s, about 80 percent of all students in the top quartile of ability continued to college after high school. Among the high school graduates in the top few percentiles of cognitive ability, the chances of going to college already exceeded 90 percent.

Perhaps the most important of all the changes was the transformation of America’s elite colleges. As more bright youngsters went off to college, the colleges themselves began to sort themselves out. Starting in the 1950s, a handful of institutions became magnets for the very brightest of each year’s new class. In these schools, the cognitive level of the students rose far above the rest of the college population.

Taken together, these trends have stratified America according to cognitive ability.

Chapter 2. Cognitive Partitioning by Occupation

People in different jobs have different average IQs. Lawyers, for example, have higher IQs on the average than bus drivers. Whether they must have higher IQs than bus drivers is a topic we take up in detail in the next chapter. Here we start by noting simply that people from different ranges on the IQ scale end up in different jobs.

Whatever the reason for the link between IQ and occupation, it goes deep. If you want to guess an adult male’s job status, the results of his childhood IQ test help you as much as knowing how many years he went to school. IQ becomes more important as the job gets intellectually tougher. To be able to dig a ditch, you need a strong back but not necessarily a high IQ score. To be a master carpenter, you need some higher degree of intelligence along with skill with your hands. To be a first-rate lawyer, you had better come from the upper end of the cognitive ability distribution. The same may be said of a handful of other occupations, such as accountants, engineers and architects, college teachers, dentists and physicians, mathematicians, and scientists. The mean IQ of people entering those fields is in the neighborhood of 120. In 1900, only one out of twenty people in the top 10 percent in intelligence were in any of these occupations, a figure that did not change much through 1940. But after 1940, more and more people with high IQs flowed into those jobs, and by 1990 the same handful of occupations employed about 25 percent of all the people in the top tenth of intelligence.

During the same period, IQ became more important for business executives. In 1900, the CEO of a large company was likely to be a WASP born into affluence. He may have been bright, but that was not mainly how he was chosen. Much was still the same as late as 1950. The next three decades saw a great social leveling, as the executive suites filled with bright people who could maximize corporate profits, and never mind if they came from the wrong side of the tracks or worshipped at a temple instead of a church. Meanwhile, the college degree became a requirement for many business positions, and graduate education went from a rarity to a commonplace among senior executives.

Even as recently as midcentury, America was still a society in which most bright people were scattered throughout awide range of jobs.

When one combines the people known to be in high IQ professions with estimates of the numbers of business executives who are drawn from the top tenth in cognitive ability, the results do not leave much room for maneuver. The specific proportions are open to argument, but the main point seems beyond dispute: Even as recently as midcentury, America was still a society in which most bright people were scattered throughout awide range of jobs. As the century draws to a close, a very high proportion of that same group is now concentrated within a few occupations that are highly screened for IQ.

Chapter 3. The Economic Pressure to Partition

What accounts for the way that people with different levels of IQ end up in different occupations? The fashionable explanation has been education. People with high SAT scores get into the best colleges; people with the high GRE, MCAT, or LSAT test scores get into professional and graduate schools; and the education defines the occupation. The SAT score becomes unimportant once the youngster has gotten into the right college or graduate school.

Without doubt, education is part of the explanation; physicians need a high IQ to get into medical school, but they also need to learn the material that medical school teaches before they can be physicians. Plenty of hollow credentialing goes on as well, if not in medicine then in other occupations, as the educational degree becomes a ticket for jobs that could be done just as well by people without the degree.

But the relationship of cognitive ability to job performance goes beyond that. A smarter employee is, on the average, a more proficient employee. This holds true within professions: Lawyers with higher IQs are, on the average, more productive than lawyers with lower IQs. It holds true for skilled blue-collar jobs: Carpenters with high IQs are also (on average) more productive than carpenters with lower IQs. The relationship holds, although weakly, even among people in unskilled manual jobs.

The magnitude of the relationship between cognitive ability and job performance is greater than once thought. A flood of new analyses during the 1980s established several points with large economic and policy implications: Test scores predict job performance because they measure g, Spearman’s general intelligence factor, not because they identify “aptitude” for a specific job. Any broad test of general intelligence predicts proficiency in most common occupations, and does so more accurately than tests that are narrowly constructed around the job’s specific tasks.

The advantage conferred by IQ is long-lasting. Much remains to be learned, but usually the smarter employee tends to remain more productive than the less smart employee even after years on the job.
Laws can make the economy less efficient by forbidding employers to use intelligence tests, but laws cannot make intelligence unimportant.

An IQ score is a better predictor of job productivity than a job interview, reference checks, or college transcript.

Most sweepingly important, an employer that is free to pick among applicants can realize large economic gains from hiring those with the highest IQs. An economy that lets employers pick applicants with the highest IQs is a significantly more efficient economy. Herein lies the policy problem: Since 1971, Congress and the Supreme Court have effectively forbidden American employers from hiring based on intelligence tests. How much does this policy cost the economy? Calculating the answer is complex, so estimates vary widely, from what one authority thinks was a lower-bound estimate of $80 billion in 1980 to what another authority called an upper-bound estimate of $13 billion for that year.

Our main point has nothing to do with deciding how large the loss is or how large the gain would be if intelligence tests could be freely used for hiring. Rather, it is simply that intelligence itself is importantly related to job performance. Laws can make the economy less efficient by forbidding employers to use intelligence tests, but laws cannot make intelligence unimportant.

Chapter 4. Steeper Ladders, Narrower Gates

Cognitive partitioning through education and occupations will continue, and there is not much that the government or anyone else can do about it. Economics will be the main reason. At the same time that elite colleges and professional schools are turning out brighter and brighter graduates, the value of intelligence in the marketplace is rising. Wages earned by people in high-IQ occupations have pulled away from the wages in low-IQ occupations, and differences in education cannot explain most of this change.

Another force for cognitive partitioning is the increasing physical segregation of the cognitive elite from the rest of society. Members of the cognitive elite work in jobs that usually keep them off the shop floor, away from the construction site, and close to others who also tend to be smart. Computers and electronic communication make it increasingly likely that people who work mainly with their minds collaborate only with other such people. The isolation of the cognitive elite is compounded by its choices of where to live, shop, play, worship, and send its children to school.

Its isolation is intensified by an irony of a mobile and democratic society like America’s. Cognitive ability is a function of both genes and environment, with implications for egalitarian social policies. The more we succeed in giving every youngster a chance to develop his or her latent cognitive ability, the more we equalize the environmental sources of differences in intelligence. The irony is that as America equalizes the circ*mstances of people’s lives, the remaining differences in intelligence are increasingly determined by differences in genes. Meanwhile, high cognitive ability means, more than ever before, that the chances of success in life are good and getting better all the time. Putting it all together, success and failure in the American economy, and all that goes with it, are increasingly a matter of the genes that people inherit.

Add to this the phenomenon known as assortative mating. Likes attract when it comes to marriage, and intelligence is one of the most important of those likes. When this propensity to mate by IQ is combined with increasingly efficient educational and occupational stratification, assortative mating by IQ has more powerful effects on the next generation than it had on the previous one. This process too seems to be getting stronger, part of the brew creating an American class system.

From THE BELL CURVE by Richard J. Hernstein 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.