The Bell Curve

The Bell Curve
The Bell Curve  
Author(s) Richard J. Herrnstein, Charles Murray
Publisher Free Press
Publication date September 1994
Media type Hardcover
Pages 845
ISBN ISBN 0-02-914673-9
OCLC Number 30913157
Dewey Decimal 305.9/082 20
LC Classification BF431 .H398 1994

The Bell Curve is a best-selling and controversial 1994 book by the Harvard psychologist Richard J. Herrnstein (deceased before the book was released) and political scientist Charles Murray. Its central argument is that intelligence is substantially influenced by both inherited and environmental factors and is a better predictor of many personal dynamics, including financial income, job performance, chance of unwanted pregnancy, and involvement in crime than are an individual's parental socioeconomic status, or education level. The book also argues that those with high intelligence, the "cognitive elite", are becoming separated from those of average and below-average intelligence, and that this is a dangerous social trend with the United States moving toward a more divided society similar to that in Latin America.

Much of the controversy concerned the parts of the book in which the authors wrote about racial differences in intelligence and discuss the implications of those differences. The authors were reported throughout the popular press as arguing that these IQ differences are genetic, and they did indeed write in chapter 13: "It seems highly likely to us that both genes and the environment have something to do with racial differences." The introduction to the chapter more cautiously states, "The debate about whether and how much genes and environment have to do with ethnic differences remains unresolved."

The book's title comes from the bell-shaped normal distribution of intelligence quotient (IQ) scores in a population.

Shortly after publication, many people rallied both in criticism and defense of the book. A number of critical texts were written in response to the book.



The Bell Curve, published in 1994, was written by Richard Herrnstein and Charles Murray as a work designed to explain, using empirical statistical analysis, the variations in intelligence in American Society, raise some warnings regarding the consequences of this intelligence gap, and propose national social policy with the goal of mitigating the worst of the consequences attributed to this intelligence gap. Many of the assertions put forth and conclusions reached by the authors are very controversial, ranging from the relationships between low measured intelligence and anti-social behavior, to the observed relationship between low African-American test scores (compared to whites and Asians) and genetic factors in intelligence abilities. The book was released and received with a large public response. In the first several months of its release, 400,000 copies of the book were sold around the world. Several thousand reviews and commentaries have been written in the short time since the book's publication. Herrnstein and Murray in many ways follow in the footsteps of UC Berkeley researcher Arthur Jensen, whose controversial article on the subject appeared in 1969 in the Harvard Educational Review. The Bell Curve argues that:

  1. Intelligence exists and is accurately measurable across racial, language, and national boundaries.
  2. Intelligence is one of, if not the most, important factors correlated to economic, social, and overall success in the United States, and its importance is increasing.
  3. Intelligence is largely (40% to 80%) heritable.
  4. No one has so far been able to manipulate IQ to a significant degree through changes in environmental factors—except for child adoption and that they conclude is not large in the long term—and in light of these failures, such approaches are becoming less promising.
  5. The USA has been in denial of these facts. A better public understanding of the nature of intelligence and its social correlates is necessary to guide future policy decisions.

Their evidence comes from an analysis of data compiled in the National Longitudinal Study of Youth (NLSY), a study conducted by the United States Department of Labor's Bureau of Labor Statistics tracking thousands of Americans starting in the 1980s. All participants in the NLSY took the Armed Services Vocational Aptitude Battery (ASVAB), a battery of ten tests taken by all who apply for entry into the armed services. (Some had taken an IQ test in high school, and the median correlation of the AFQT and those tests was .81.) Participants were later evaluated for social and economic outcomes. In general, IQ/AFQT scores were a better predictor of life outcomes than social class background. Similarly, after statistically controlling for differences in IQ, many outcome differences between racial-ethnic groups disappeared.

Economic and social correlates of IQ
IQ <75 75-90 90-110 110-125 >125
US population distribution 5 20 50 20 5
Married by age 30 72 81 81 72 67
Out of labor force more than 1 month out of year (men) 22 19 15 14 10
Unemployed more than 1 month out of year (men) 12 10 7 7 2
Divorced in 5 years 21 22 23 15 9
 % of children w/ IQ in bottom decile (mothers) 39 17 6 7 -
Had an illegitimate baby (mothers) 32 17 8 4 2
Lives in poverty 30 16 6 3 2
Ever incarcerated (men) 7 7 3 1 0
Chronic welfare recipient (mothers) 31 17 8 2 0
High school dropout 55 35 6 0.4 0
Values are the percentage of each IQ sub-population, among non-Hispanic whites only, fitting each descriptor. Herrnstein & Murray (1994) pp. 171, 158, 163, 174, 230, 180, 132, 194, 247-248, 194, 146 respectively.

They also stated that the average IQ of African Americans is 85; Latinos 89; Whites 103; Asians 106; and Jews 113.

Policy recommendations

The book argued the average genetic IQ of the United States is declining due to the tendency of the more intelligent to have fewer children than the less intelligent, for the generation length to be shorter for the less intelligent, and through the large scale immigration to the United States of those with low intelligence. The United States will become increasingly like Latin America, with high IQ whites and Asians living in fortified enclaves protected by high fences and armed guards from "the menace of the slums" below.

In a discussion of the future political outcomes of an intellectually stratified society, they stated that they "fear that a new kind of conservatism is becoming the dominant ideology of the affluent - not in the social tradition of an Edmund Burke or in the economic tradition of an Adam Smith but 'conservatism' along Latin American lines, where to be conservative has often meant doing whatever is necessary to preserve the mansions on the hills from the menace of the slums below".[1] Moreover, they fear that increasing welfare will create a "custodial state" in "a high-tech and more lavish version of the Indian reservation for some substantial minority of the nation's population." They also predict increasing totalitarianism: "It is difficult to imagine the United States preserving its heritage of individualism, equal rights before the law, free people running their own lives, once it is accepted that a significant part of the population must be made permanent wards of the states".[2]

Herrnstein and Murray recommended the elimination of welfare policies that encourage poor women to have babies:

We can imagine no recommendation for using the government to manipulate fertility that does not have dangers. But this highlights the problem: The United States already has policies that inadvertently social-engineer who has babies, and it is encouraging the wrong women. "If the United States did as much to encourage high-IQ women to have babies as it now does to encourage low-IQ women, it would rightly be described as engaging in aggressive manipulation of fertility." The technically precise description of America's fertility policy is that it subsidizes births among poor women, who are also disproportionately at the low end of the intelligence distribution. We urge generally that these policies, represented by the extensive network of cash and services for low-income women who have babies, be ended. The government should stop subsidizing births to anyone rich or poor. The other generic recommendation, as close to harmless as any government program we can imagine, is to make it easy for women to make good on their prior decision not to get pregnant by making available birth control mechanisms that are increasingly flexible, foolproof, inexpensive, and safe.[3]

This claim spurred later research in economics and sexology, which considered that welfare programs for women had a doubly negative effect on aggregate IQ within the transfer group, by allowing the female partner to forgo a full consideration of the male's ability to serve as a provider of familial resources, instead placing greater emphasis on desirable physical or social characteristics (presumed to be not as positively correlated with IQ). Neither of these claims, as originally embodied in text and the follow-on research, dealt with race as such, but rather demonstrated concern that large numbers of minorities were positioned as recipients, leading to a continual worsening of the measured divergence in intelligence. However, two years later, the 1996 U.S. welfare reform substantially cut these programs..

The book also argued for reducing immigration into the US which was argued to lower the average national IQ. It also recommended against policies of affirmative action.

g factor

Knowledge of the general intelligence factor (g) is important to evaluate the debates on testing. The g factor is an almost universally supported, and very important, construct in psychometry.[4] In a battery of mental ability tests given to a group of people, all the tests are positively correlated with each other; those who are above average in one will, on average, be above average on the others.

Factor analysis can extract a smaller number of factors to account for the variation in the scores; this is possible because the more two tests measure the same thing, the greater their correlations will be. One factor, g can then be extracted (sometimes after another layer of specific factors are removed). The correlation of the test scores with g is its g-loading; a high one is desirable in a test.

g is correlated with a wide range of social outcomes; some are such as income, academic achievement, job performance, and career prestige, poverty, dropping out, and out-of-marriage childbirth. g correlates with both speed and consistency of performance on elementary cognitive tasks (simple ones that can be done by everybody without failure). All of this was mentioned in The Bell Curve, and many biological and neurological correlates have been discovered since, in addition to the long known ones such as brain size. These include the frequency of alpha brain waves, latency and amplitude of evoked brain potentials, rate of brain glucose metabolism, and general health as some of the best established ones. Almost all of a test's predictive validity lies in g, as opposed to the more specific factors. The AFQT and IQ tests are very highly g-loaded.


Media response

A 1995 article by Fairness and Accuracy in Reporting writer Jim Naureckas analyzed the media response. The Bell Curve received a great deal of media attention. He wrote "While many of these discussions included sharp criticisms of the book, media accounts showed a disturbing tendency to accept Murray and Herrnstein's premises and evidence even while debating their conclusions" and "their critics were sometimes identified with censorious political correctness". Naureckas criticized these assumptions. He also argued that the book was part of a campaign to justify racism and against welfare and immigration.[5]

Peer review

An early criticism was that Herrnstein and Murray did not submit their work to peer review before publication.[6] Many scholarly reviews of the book arrived later as discussed below. Richard Lynn (1999) wrote that "The book has been the subject of several hundred critical reviews, a number of which have been collected in edited volumes".[7]

"Mainstream Science on Intelligence"

Fifty-two professors, most of them psychologists including researchers in the study of intelligence and related fields, signed an opinion statement titled "Mainstream Science on Intelligence"[8] endorsing the views presented in The Bell Curve. The statement was written by psychologist Linda Gottfredson and published in The Wall Street Journal in 1994 and reprinted in the Intelligence.[9] Of the 131 who were invited by mail to sign the document, 100 responded, with 52 agreeing to sign and 48 declining. Eleven of the 48 dissenters claimed that the statement did not represent the mainstream view of intelligence. Some of the signatories had been cited as sources for Murray and Herrnstein's book.

APA task force report

In response to the growing controversy surrounding The Bell Curve, the American Psychological Association's Board of Scientific Affairs established a special task force to publish an investigative report on the research presented in the book.[10] The final report, titled Intelligence: Knowns and Unknowns, is available at an academic website.[11] Some of the task force's findings supported or were consistent with statements from The Bell Curve. They agreed that:

  • IQ scores have high predictive validity for individual differences in school achievement.
  • IQ scores have predictive validity for adult occupational status, even when variables such as education and family background have been statistically controlled.
  • IQ scores predict future achievement equally well for blacks and whites.
  • Individual differences in intelligence are substantially influenced by both genetics and environment.[dubious ]
  • There is little evidence to show that childhood diet influences intelligence except in cases of severe malnutrition.
  • There are no statistically significant differences between the IQ scores of males and females.

Regarding Murray and Herrnstein's claims about racial differences and genetics, the APA task force stated:

There is certainly no such support for a genetic interpretation... . It is sometimes suggested that the Black/ White differential in psychometric intelligence is partly due to genetic differences (Jensen, 1972). There is not much direct evidence on this point, but what little there is fails to support the genetic hypothesis.

Regarding statements about other explanations for racial differences, the APA task force stated:

The differential between the mean intelligence test scores of Blacks and Whites (about one standard deviation, although it may be diminishing) does not result from any obvious biases in test construction and administration, nor does it simply reflect differences in socio-economic status. Explanations based on factors of caste and culture may be appropriate, but so far have little direct empirical support.

Regarding statements about any explanations for racial differences, the APA task force stated: "At present, no one knows what causes this differential." The APA journal that published the statement, American Psychologist, subsequently published eleven critical responses in January 1997.


The validity of IQ and g

One part of the criticism of The Bell Curve focused on the validity of IQ and g. William J. Matthews and Stephen Jay Gould (1994) listed four basic assumptions of The Bell Curve. According to Gould, if any of these premises are false, then their entire argument disintegrates (Gould, 1994).[12]

  1. Intelligence must be reducible to a single number.
  2. Intelligence must be capable of rank ordering people in a linear order.
  3. Intelligence must be primarily genetically based.
  4. Intelligence must be essentially immutable.

Similarly, in anthropologist C. Loring Brace in a review wrote that The Bell Curve made six basic assumptions at the beginning of the book. He argued that there are faults in every one of these assumptions.[13]

  1. Human Cognitive ability is a single general entity, depictable as a single number.
  2. Cognitive ability has a heritability of between 40 and 80 percent and is therefore primarily genetically based.
  3. IQ is essentially immutable, fixed over the course of a life span.
  4. IQ tests measure how "smart" or "intelligent" people are and are capable of rank ordering people in a linear order.
  5. IQ tests can measure this accurately.
  6. IQ tests are not biased with regard to race ethnic group or socioeconomic status.

The importance of IQ for life outcomes

The Nobel Prize winning economist James Heckman writes that two assumptions made in the book are questionable: that g accounts for correlation across test scores and performance in society, and that g cannot be manipulated. Heckman writes that a reanalysis of the evidence used in The Bell Curve contradicts this story. The factors that explain wages receive different weights than the factors that explain test scores. More than g is required to explain either. Other factors besides g contribute to social performance, and they can be manipulated.[14] Murray argued that this was a straw man and that the book does not argue that g or IQ are totally immutable or the only factors affecting outcomes.[15]

Michael Hout of the University of California at Berkeley, along with five colleagues, recalculated the effect of socioeconomic status, using the same variables as The Bell Curve, but weighting them differently. They found that if IQ scores are corrected, as Herrnstein and Murray did, to eliminate the effect of education, the ability of IQ to predict poverty can be made to look dramatically overstated, by as much as 61 percent for whites and 74 percent for blacks. In other words, according to Hout et al., Herrnstein and Murray's finding, that IQ predicts poverty much better than socioeconomic status does, is substantially a result of the way they handled the statistics.[16]

In August 1995, at the National Bureau of Economic Research economist Sanders Korenman and Harvard University sociologist Christopher Winship found certain errors in Herrnstein's methodology. Korenman and Winship concluded:"... there is evidence of substantial bias due to measurement error in their estimates of the effects of parents' socioeconomic status. In addition, Herrnstein and Murray's measure of parental socioeconomic status (SES) fails to capture the effects of important elements of family background (such as single-parent family structure at age 14). As a result, their analysis gives an exaggerated impression of the importance of IQ relative to parents' SES, and relative to family background more generally. Estimates based on a variety of methods, including analyses of siblings, suggest that parental family background is at least as important, and may be more important than IQ in determining socioeconomic success in adulthood."[17]

One early critical book was The Bell Curve Debate.

In the book Intelligence, Genes, and Success: Scientists Respond to The Bell Curve, a group of social scientists and statisticians analyzes the genetics-intelligence link, the concept of intelligence, the malleability of intelligence and the effects of education, the relationship between cognitive ability, wages and meritocracy, pathways to racial and ethnic inequalities in health, and the question of public policy. This work argues that much of the public response was polemic, and failed to analyze the details of the science and validity of the statistical arguments underlying the book's conclusions.[18]

William J. Matthews writes that part of The Bell Curve's analysis is based on the AFQT "which is not an IQ test but designed to predict performance of certain criterion variables".[19] Heckman observed that the AFQT was designed only to predict success in military training schools and that most of these tests appear to be achievement tests rather than ability tests, measuring factual knowledge and not pure ability. He continues:

Ironically, the authors delete from their composite AFQT score a timed test of numerical operations because it is not highly correlated with the other tests. Yet it is well known that in the data they use, this subtest is the single best predictor of earnings of all the AFQT test components. The fact that many of the subtests are only weakly correlated with each other, and that the best predictor of earnings is only weakly correlated with their "g-loaded" score, only heightens doubts that a single-ability model is a satisfactory description of human intelligence. It also drives home the point that the "g-loading" so strongly emphasized by Murray and Herrnstein measures only agreement among tests—not predictive power for socioeconomic outcomes. By the same token, one could also argue that the authors have biased their empirical analysis against the conclusions they obtain by disregarding the test with the greatest predictive power.[14][20]

Janet Currie and Duncan Thomas presented evidence suggesting AFQT scores are likely better markers for family background than "intelligence" in a 1999 Study.

Herrnstein and Murray report that conditional on maternal "intelligence" (AFQT scores), child test scores are little affected by variations in socio-economic status. Using the same data, we demonstrate their finding is very fragile.[21]

Charles R. Tittle, Thomas Rotolo found that the more that written, IQ-like examinations are used as screening devices for occupational access, the stronger the relationship between IQ and income. Thus, rather than higher IQ leading to status attainment because it indicates skills needed in a modern society, IQ may reflect the same test-taking abilities used in artificial screening devices by which status groups protect their domains.[22]

Min-Hsiung Huang and Robert M. Hauser write that Herrnstein and Murray provide scant evidence of growth in cognitive sorting. Using data from the General Social Survey, they tested each of these hypotheses using a short verbal ability test which was administered to about 12,500 American adults between 1974 and 1994; the results provided no support for any of the trend hypotheses advanced by Herrnstein and Murray. One chart in The Bell Curve purports to show that people with IQs above 120 have become "rapidly more concentrated" in high-IQ occupations since 1940. But Robert Hauser and his colleague Min-Hsiung Huang retested the data and came up with estimates that fell “well below those of Herrnstein and Murray." They add that the data, properly used, "do not tell us anything except that selected, highly educated occupation groups have grown rapidly since 1940."[23]

In 1972, Noam Chomsky questioned Herrnstein's idea that society was developing towards a meritocracy. Chomsky criticized the assumptions that people only seek occupations based on material gain. He argued that Herrnstein would not want to become a baker or lumberjack even if he could earn more money that way. He also criticized that assumption that such a society would be fair with pay based on value of contributions. He argued that because there are already unjust great inequalities, people will often be paid, not for valuable contributions to society, but to preserve such inequalities.[24]

In 1995, Chomsky directly criticized the book and its assumptions on IQ. He takes issue with the idea that IQ is 60% heritable saying, the "statement is meaningless" since heritability doesn't have to be genetic. He gives the example of women wearing earings:

To borrow an example from Ned Block, "some years ago when only women wore earrings, the heritability of having an earring was high because differences in whether a person had an earring was due to a chromosomal difference, XX vs. XY." No one has yet suggested that wearing earrings, or ties, is "in our genes," an inescapable fate that environment cannot influence, "dooming the liberal notion."[25]

He goes on to say there is almost no evidence of a genetic link, and greater of evidence of environmental issues are what determine IQ differences.

Race and intelligence

One part of the controversy concerned the parts of the book which dealt with racial group differences on IQ and the consequences of this. The authors were reported throughout the popular press as arguing that these IQ differences are genetic, and they did indeed write in chapter 13: "It seems highly likely to us that both genes and the environment have something to do with racial differences." The introduction to the chapter more cautiously states, "The debate about whether and how much genes and environment have to do with ethnic differences remains unresolved."

Economist and conservative writer Thomas Sowell criticized the book's conclusions about race and the malleability of IQ, writing:[26]

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... 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.

Rushton (1997) as well as Cochran et al. (2005) have argued that also the early testing does in fact support a high average Jewish IQ.[27][28]

Columnist Bob Herbert, writing for The New York Times, described the book as "a scabrous piece of racial pornography masquerading as serious scholarship." "Mr. Murray can protest all he wants," wrote Herbert; "his book is just a genteel way of calling somebody a nigger."[29]

One prominent critic of The Bell Curve was the late Stephen Jay Gould, who in 1996 released a revised and expanded edition of his 1981 book The Mismeasure of Man intended to more directly refute many of The Bell Curve's claims regarding race and intelligence. Specifically, Gould argued that the then-current evidence showing heritability of IQ did not indicate a genetic origin to group differences in intelligence. This book has in turn been criticized.[30][31]

Melvin Konner, professor of anthropology and associate professor of psychiatry and neurology at Emory University, called Bell Curve a "deliberate assault on efforts to improve the school performance of African-Americans":

This book presented strong evidence that genes play a role in intelligence but linked it to the unsupported claim that genes explain the small but consistent black-white difference in IQ. The juxtaposition of good argument with a bad one seemed politically motivated, and persuasive refutations soon appeared. Actually, African-Americans have excelled in virtually every enriched environment they have been placed in, most of which they were previously barred from, and this in only the first decade or two of improved but still not equal opportunity. It is likely that the real curves for the two races will one day be superimposable on each other, but this may require decades of change and different environments for different people. Claims about genetic potential are meaningless except in light of this requirement.[32]

Noam Chomsky in 1972 in an earlier debate with Herrnstein argued that even if there is a correlation between race and intelligence, this would have no "social consequences except in a racist society in which each individual is assigned to a racial category and dealt with not as an individual in his own right, but as a representative of this category … In a non-racist society, the category of race would be of no greater significance [than height].[24]

In 1995, Chomsky criticized the book's accusations about race, saying that there is little evidence that IQ is genetic but that it's influenced by the environment. He goes on to criticize the notion that Blacks and people with lower IQs having more children is even a problem and criticized solutions the authors propose to stop it:

There's an easy solution to the problem: simply bring here millions of peasants driven from the countryside in China ...and radically reduce Browne's income...while Black mothers are placed in Manhattan high rises and granted every advantage. Then the Asian influx will raise the IQ level; and as serious inquiry demonstrates, the fertility rate of Blacks is very likely to drop while that of the children of the journalistic elite, Harvard psychology professors, and associates of the American Enterprise Institute will rapidly rise. The problem is solved;[25]

Rutledge M. Dennis suggests that through soundbites of works like Jensen's famous study on the achievement gap, and Herrnstein and Murray's book The Bell Curve, the media "paints a picture of Blacks and other people of color as collective biological illiterates—as not only intellectually unfit but evil and criminal as well," thus providing, he says "the logic and justification for those who would further disenfranchise and exclude racial and ethnic minorities."[33]

Critic Charles Lane pointed out that 17 of the researchers whose work is referenced by the book have also contributed to Mankind Quarterly, a journal of anthropology founded in 1960 in Edinburgh, which has been viewed as supporting the theory of the genetic superiority of the whites.[34]

In his book The Bell Curve Wars: Race, Intelligence, and the Future of America, Steven Fraser writes that "by scrutinizing the footnotes and bibliography in The Bell Curve, readers can more easily recognize the project for what it is: a chilly synthesis of the work of disreputable race theorists and eccentric eugenicists".[35]

Since the book provided its scientifically derived, quantifiable statistical data supporting the assertion that blacks were, on average, less intelligent than whites, some people have feared that The Bell Curve could be used by extremists to justify genocide and hate crimes.[36][37] Critics have noted much of the work referenced by the Bell Curve was funded by the Pioneer Fund, which aims to advance the scientific study of heredity and human differences, and has been accused of promoting scientific racism.[38][39][40]

Evolutionary biologist Joseph L. Graves described the Bell Curve as an example of racist science, containing all the types of errors in the application of scientific method that have charcaterized the history of Scientific racism:

  1. claims that are not supported by the data given
  2. errors in calculation that invariably support the hypothesis
  3. no mention of data that contradicts the hypothesis
  4. no mention of theories and data that conflict with core assumptions
  5. bold policy recommendations that are consistent with those advocated by racists.[41]

Author's follow-up

Relation between IQ and earnings in the U.S.
IQ <75 75–90 90–110 110–125 >125
Age 18 2,000 5,000 8,000 8,000 3,000
Age 26 3,000 10,000 16,000 20,000 21,000
Age 32 5,000 12,400 20,000 27,000 36,000
Values are the average earnings (1993 US Dollars) of each IQ sub-population.[42]

Murray responded to specific criticisms of the analysis of the practical importance of IQ compared to socio-economic status (Part II of The Bell Curve) in a 1998 book Income Inequality and IQ[43] To circumvent criticisms surrounding their use of a statistical control for socioeconomic status (SES), Murray adopted a sibling design. Rather than statistically controlling for parental SES, Murray compared life outcome differences among full sibling pairs who met a number of criteria in which one member of the pair has an IQ in the "normal" range and the other siblings has an IQ in a higher or lower IQ category. According to Murray, this design controls for all aspects of family background (full siblings share the same family background, growing up together in the same home and the same community).

Comparison of The Bell Curve control for parental SES and the sibling fixed-effect model of IQ and Income Inequality for IQ regression
Indicator Bell Curve control for parental SES Sibling fixed-effect model
Annual earnings, year-round workers 5548 5317
Years of schooling 0.59 0.45
Attainment of BA 1.76 1.87
High-IQ occupation 1.39 1.72
Out of labor force 1+ month -0.34 -0.3
Unemployed 1+ month -0.52 -0.47
Relation between IQ and life outcomes in the U.S. among sibling pairs in a "Utopian" sample
IQ <75 75–90 90–110 110–125 >125
Mean years of education 11.4 (10.9) 12.3 (11.9) 13.4 (13.2) 15.2 (15.0) 16.5 (16.5)
Percentage obtaining B.A. 1 (1) 4 (3) 19 (16) 57 (50) 80 (77)
Mean weeks worked 35.8 (30.7) 39.0 (36.5) 43.0 (41.8) 45.1 (45.2) 45.6 (45.4)
Mean earned income 11,000 (7,500) 16,000 (13,000) 23,000 (21,000) 27,000 (27,000) 38,000 (36,000)
Percentage with a spouse who has earned income 30 (27) 38 (39) 53 (54) 61 (59) 58 (58)
Mean earned family income 17,000 (12,000) 25,000 (23,400) 37,750 (37,000) 47,200 (45,000) 53,700 (53,000)
Percentage children born out of wedlock 49 (50) 33 (32) 14 (14) 6 (6) 3 (5)
Fertility to date 2.1 (2.3) 1.7 (1.9) 1.4 (1.6) 1.3 (1.4) 1.0 (1.0)
Mother's mean age at birth 24.4 (22.8) 24.5 (23.7) 26.0 (25.2) 27.4 (27.1) 29.0 (28.5)
Values are "Utopian sample" ("Full sample"). Earning values are the 1993 US Dollars.[43]


  1. ^ p. 518.
  2. ^ p. 526.
  3. ^ pp. 548-549.
  4. ^ Arthur R. Jensen (1999) "The g factor: the science of mental ability", Psycoloquy, 10(23)
  5. ^ Racism Resurgent:How Media Let The Bell Curve's Pseudo-Science Define the Agenda on Race By Jim Naureckas January/February 1995
  6. ^ Arthur S. Goldberger and Charles F. Manski (1995) "Review Article: The Bell Curve by Herrnstein and Murray", Journal of Economic Literature, 36(2), June 1995, pp. 762-776. "HM and their publishers have done a disservice by circumventing peer review. ...a process of scientific review is now under way. But, given the process to date, peer review of The Bell Curve is now an exercise in damage control...."
  7. ^ Richard Lynn (1999) The Attack on The Bell Curve Personality and Individual Differences 26, pp. 761–765
  8. ^ See: "Mainstream Science on Intelligence", Wall Street Journal, December 13, 1994.
  9. ^ See: Linda Gottfredson (1997) "Mainstream Science on Intelligence", Intelligence, 24(1), pages 13-23.
  10. ^ See: The APA 1996 Intelligence Task Force Report.
  11. ^ See: Ulric Neisser (Chair) et al. (1996) "Intelligence: Knowns and Unknowns", American Psychologist, 51(2), pages 77-101..
  12. ^ A Review of the Bell Curve: Bad Science Makes for Bad Conclusions
  13. ^ "Science" in the Service of Racism
  14. ^ a b Heckman, James J. (1995). "Lessons from the Bell Curve". Journal of Political Economy 103 (5): 1091–1120. doi:10.1086/262014 .
  15. ^ August 1995 letter exchange in Commentary magazine
  16. ^ Inequality by Design:Cracking the Bell Curve Myth Claude S. Fischer, Michael Hout, Martín Sánchez Jankowski, Samuel R. Lucas, Ann Swidler, and Kim Vos
  17. ^ Korenman, Sanders and Winship, Christopher, "A Reanalysis of The Bell Curve" (August 1995). NBER Working Paper Series, Vol. w5230, 1995.
  18. ^ Intelligence, Genes, and Success: Scientists Respond to "the Bell Curve" Bernie Devlin, Richard J. Herrnstein ISBN 0387949860
  19. ^ William J. Matthews, Ph.D. (1998) A Review of the Bell Curve: Bad Science Makes for Bad Conclusions
  20. ^ Cracked Bell James J. Heckman. March 1995. Reason
  21. ^ The Intergenerational Transmission of 'Intelligence' Down the Slippery Slopes of 'The Bell Curve' Industrial Relations: A Journal of Economy and Society, Vol. 38, No. 3, July 1999
  22. ^ IQ and Stratification: An Empirical Evaluation of Herrnstein and Murray's Social Change Argument Charles R. Tittle, Thomas Rotolo Social Forces, Vol. 79, No. 1 (Sep., 2000), pp. 1-28
  23. ^ Verbal Ability and Socioeconomic Success: A Trend Analysis Hauser R.M.; Huang M.H.
  24. ^ a b Chomsky, Noam. 1972. ‘Chomsky on IQ and inequality I.Q. Tests: Building Blocks for the New Class System.’ Rampart:24–30. pp. 26, 27, 28, 30.
  25. ^ a b Rollback, Part II Noam Chomsky, 1995
  26. ^ Sowell, Thomas (1995). "Ethnicity and IQ". The American Spectator 28 (2). 
  27. ^ Cochran, G.; Hardy, J.; Harpending, H. (2006). "Natural history of Ashkenazi intelligence". Journal of biosocial science 38 (5): 659–693. doi:10.1017/S0021932005027069. PMID 16867211.  edit
  28. ^ Rushton J. P. (1997). "Race, Intelligence, And The Brain" (PDF). Personality and Individual Differences 23 (1): 169–180. doi:10.1016/S0191-8869(97)80984-1. 
  29. ^ Herbert, Bob (1994-10-26). "In America; Throwing a Curve". The New York Times. Retrieved 2007-01-09. 
  30. ^ Flynn, J. R. (1999). Evidence against Rushton: The Genetic Loading of the Wisc-R Subtests and the Causes of Between-Group IQ Differences. Personality and Individual Differences, 26, p. 373-93.
  31. ^ Humphreys, L. (1983). Review of The Mismeasure of Man by Stephen Jay Gould. American Journal of Psychology, 96, p. 407–415.
  32. ^ The Tangled Wing Biological Constraints on the Human Spirit by Melvin Konner, 2nd edition, p. 428
  33. ^ Social Darwinism, scientific racism, and the metaphysics of race Journal of Negro Education, The, Summer 1995 by Dennis, Rutledge M
  34. ^ Charles Lane, "The Tainted Sources of ‘The Bell Curve’", New York Review of Books, December 1, 1994.
  35. ^ The Bell Curve Wars: Race, Intelligence, and the Future of America Book by Steven Fraser; Basic Books, 1995
  36. ^ Ann Coulter and Charles Darwin. Coultergeist by Jerry Coyne
  37. ^ The Bell Curve: An illustration of the existence of social science as a social problem
  38. ^ Racism Resurgent
  39. ^ ABC World News Tonight. November 22, 1994
  40. ^, The Bell Curve Revisited, Stephen Metcalf, October 17, 2005.
  41. ^ Graves, Joseph, L. 2001. The Emperor's New Clothes. Rutgers University Press. p. 8
  42. ^ Murray, C. (1997). IQ and economic success. Public Interest, 128, 21–35.
  43. ^ a b Murray, C. (1998). Income Inequality and IQ. Washington: AEI Press.


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