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The Bell Curve

The Bell Curve

Overview
The Bell Curve is a best-selling and controversial 1994 book by the Harvard
Harvard University
Harvard University is a private Ivy League university located in Cambridge, Massachusetts, United States, established in 1636 by the Massachusetts legislature. Harvard is the oldest institution of higher learning in the United States and the first corporation chartered in the country...

 psychologist
Psychologist
Psychologist is a professional or academic title used by individuals who are either:* Clinical professionals who work with patients in a variety of therapeutic contexts .* Scientists conducting psychological research or teaching psychology in a college...

 Richard J. Herrnstein
Richard Herrnstein
Richard J. Herrnstein was an American researcher in animal learning in the Skinnerian tradition. He was one of the founders of quantitative analysis of behavior....

 (deceased before the book was released) and political scientist Charles Murray
Charles Murray (author)
Charles Alan Murray is an American libertarian political scientist, author, columnist, and pundit working as a fellow at the American Enterprise Institute, a conservative think tank in Washington, DC...

. Its central argument is that intelligence
Intelligence
Intelligence has been defined in different ways, including the abilities for abstract thought, understanding, communication, reasoning, learning, planning, emotional intelligence and problem solving....

 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
Pregnancy
Pregnancy refers to the fertilization and development of one or more offspring, known as a fetus or embryo, in a woman's uterus. In a pregnancy, there can be multiple gestations, as in the case of twins or triplets...

, and involvement in crime than are an individual's parental socioeconomic status
Socioeconomic status
Socioeconomic status is an economic and sociological combined total measure of a person's work experience and of an individual's or family’s economic and social position in relation to others, based on income, education, and occupation...

, or education level.
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Encyclopedia
The Bell Curve is a best-selling and controversial 1994 book by the Harvard
Harvard University
Harvard University is a private Ivy League university located in Cambridge, Massachusetts, United States, established in 1636 by the Massachusetts legislature. Harvard is the oldest institution of higher learning in the United States and the first corporation chartered in the country...

 psychologist
Psychologist
Psychologist is a professional or academic title used by individuals who are either:* Clinical professionals who work with patients in a variety of therapeutic contexts .* Scientists conducting psychological research or teaching psychology in a college...

 Richard J. Herrnstein
Richard Herrnstein
Richard J. Herrnstein was an American researcher in animal learning in the Skinnerian tradition. He was one of the founders of quantitative analysis of behavior....

 (deceased before the book was released) and political scientist Charles Murray
Charles Murray (author)
Charles Alan Murray is an American libertarian political scientist, author, columnist, and pundit working as a fellow at the American Enterprise Institute, a conservative think tank in Washington, DC...

. Its central argument is that intelligence
Intelligence
Intelligence has been defined in different ways, including the abilities for abstract thought, understanding, communication, reasoning, learning, planning, emotional intelligence and problem solving....

 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
Pregnancy
Pregnancy refers to the fertilization and development of one or more offspring, known as a fetus or embryo, in a woman's uterus. In a pregnancy, there can be multiple gestations, as in the case of twins or triplets...

, and involvement in crime than are an individual's parental socioeconomic status
Socioeconomic status
Socioeconomic status is an economic and sociological combined total measure of a person's work experience and of an individual's or family’s economic and social position in relation to others, based on income, education, and occupation...

, 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
Latin America
Latin America is a region of the Americas where Romance languages  – particularly Spanish and Portuguese, and variably French – are primarily spoken. Latin America has an area of approximately 21,069,500 km² , almost 3.9% of the Earth's surface or 14.1% of its land surface area...

.

Much of the controversy concerned the parts of the book in which the authors wrote about racial differences in intelligence
Race and intelligence
The connection between race and intelligence has been a subject of debate in both popular science and academic research since the inception of intelligence testing in the early 20th century...

 and discuss the implications of those differences. The authors were reported throughout the popular press as arguing that these IQ differences are genetic
Genetics
Genetics , a discipline of biology, is the science of genes, heredity, and variation in living organisms....

, 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
Intelligence quotient
An intelligence quotient, or IQ, is a score derived from one of several different standardized tests designed to assess intelligence. When modern IQ tests are constructed, the mean score within an age group is set to 100 and the standard deviation to 15...

 (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.

Content


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
Arthur Jensen
Arthur Robert Jensen is a Professor Emeritus of educational psychology at the University of California, Berkeley. Jensen is known for his work in psychometrics and differential psychology, which is concerned with how and why individuals differ behaviorally from one another.He is a major proponent...

, whose controversial article on the subject appeared in 1969 in the Harvard Educational Review
Harvard Educational Review
The Harvard Educational Review is a peer-reviewed academic journal of opinion and research dealing with education, associated with the Harvard Graduate School of Education, and published by the Harvard Education Publishing Group. The journal was established in 1930.Since 1945, editorial decisions...

. 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
National Longitudinal Surveys
The National Longitudinal Surveys are a set of surveys conducted by the US Department of Labor's Bureau of Labor Statistics, designed to gather information at multiple points in time on significant life events of several population samples of US citizens, especially their labor market...

 (NLSY), a study conducted by the United States Department of Labor's
United States Department of Labor
The United States Department of Labor is a Cabinet department of the United States government responsible for occupational safety, wage and hour standards, unemployment insurance benefits, re-employment services, and some economic statistics. Many U.S. states also have such departments. The...

 Bureau of Labor Statistics
Bureau of Labor Statistics
The Bureau of Labor Statistics is a unit of the United States Department of Labor. It is the principal fact-finding agency for the U.S. government in the broad field of labor economics and statistics. The BLS is a governmental statistical agency that collects, processes, analyzes, and...

 tracking thousands of Americans starting in the 1980s. All participants in the NLSY took the Armed Services Vocational Aptitude Battery
Armed Services Vocational Aptitude Battery
The Armed Services Vocational Aptitude Battery is a multiple choice test, administered by the United States Military Entrance Processing Command, used to determine qualification for enlistment in the United States armed forces...

 (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
Social class
Social classes are economic or cultural arrangements of groups in society. Class is an essential object of analysis for sociologists, political scientists, economists, anthropologists and social historians. In the social sciences, social class is often discussed in terms of 'social stratification'...

 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
Latin America
Latin America is a region of the Americas where Romance languages  – particularly Spanish and Portuguese, and variably French – are primarily spoken. Latin America has an area of approximately 21,069,500 km² , almost 3.9% of the Earth's surface or 14.1% of its land surface area...

, 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
Conservatism
Conservatism is a political and social philosophy that promotes the maintenance of traditional institutions and supports, at the most, minimal and gradual change in society. Some conservatives seek to preserve things as they are, emphasizing stability and continuity, while others oppose modernism...

 is becoming the dominant ideology of the affluent - not in the social tradition of an Edmund Burke
Edmund Burke
Edmund Burke PC was an Irish statesman, author, orator, political theorist and philosopher who, after moving to England, served for many years in the House of Commons of Great Britain as a member of the Whig party....

 or in the economic tradition of an Adam Smith
Adam Smith
Adam Smith was a Scottish social philosopher and a pioneer of political economy. One of the key figures of the Scottish Enlightenment, Smith is the author of The Theory of Moral Sentiments and An Inquiry into the Nature and Causes of the Wealth of Nations...

 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
Menace
Menace or Maenace is an ancient Greek settlement lying to the southeast of Spain according to Strabo . The exact location is unknown to date....

 of the slums below". Moreover, they fear that increasing welfare will create a "custodial state" in "a high-tech and more lavish version of the Indian reservation
Indian reservation
An American Indian reservation is an area of land managed by a Native American tribe under the United States Department of the Interior's Bureau of Indian Affairs...

 for some substantial minority of the nation's population." They also predict increasing totalitarianism
Totalitarianism
Totalitarianism is a political system where the state recognizes no limits to its authority and strives to regulate every aspect of public and private life wherever feasible...

: "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".

Herrnstein and Murray recommended the elimination of welfare policies that encourage poor women to have babies:
This claim spurred later research in economics and sexology
Sexology
Sexology is the scientific study of human sexuality, including human sexual interests, behavior, and function. The term does not generally refer to the non-scientific study of sex, such as political analysis or social criticism....

, which considered that welfare programs
Welfare state
A welfare state is a "concept of government in which the state plays a key role in the protection and promotion of the economic and social well-being of its citizens. It is based on the principles of equality of opportunity, equitable distribution of wealth, and public responsibility for those...

 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
Personal Responsibility and Work Opportunity Act
The Personal Responsibility and Work Opportunity Reconciliation Act of 1996 is a United States federal law considered to be a fundamental shift in both the method and goal of federal cash assistance to the poor. The bill added a workforce development component to welfare legislation, encouraging...

 substantially cut these programs..

The book also argued for reducing immigration
Immigration
Immigration is the act of foreigners passing or coming into a country for the purpose of permanent residence...

 into the US which was argued to lower the average national IQ. It also recommended against policies of affirmative action
Affirmative action
Affirmative action refers to policies that take factors including "race, color, religion, gender, sexual orientation or national origin" into consideration in order to benefit an underrepresented group, usually as a means to counter the effects of a history of discrimination.-Origins:The term...

.

g factor


Knowledge of the general intelligence factor (g)
General intelligence factor
The g factor, where g stands for general intelligence, is a statistic used in psychometrics to model the mental ability underlying results of various tests of cognitive ability...

 is important to evaluate the debates on testing. The g factor is an almost universally supported, and very important, construct in psychometry
Psychometrics
Psychometrics is the field of study concerned with the theory and technique of psychological measurement, which includes the measurement of knowledge, abilities, attitudes, personality traits, and educational measurement...

. 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
Income
Income is the consumption and savings opportunity gained by an entity within a specified time frame, which is generally expressed in monetary terms. However, for households and individuals, "income is the sum of all the wages, salaries, profits, interests payments, rents and other forms of earnings...

, 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
Amplitude
Amplitude is the magnitude of change in the oscillating variable with each oscillation within an oscillating system. For example, sound waves in air are oscillations in atmospheric pressure and their amplitudes are proportional to the change in pressure during one oscillation...

 of evoked brain potentials, rate of brain glucose
Glucose
Glucose is a simple sugar and an important carbohydrate in biology. Cells use it as the primary source of energy and a metabolic intermediate...

 metabolism, and general health
Health
Health is the level of functional or metabolic efficiency of a living being. In humans, it is the general condition of a person's mind, body and spirit, usually meaning to be free from illness, injury or pain...

 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
Fairness and Accuracy in Reporting
Fairness & Accuracy In Reporting is a progressive media criticism organization based in New York City, founded in 1986.FAIR describes itself on its website as "the national media watch group" and defines its mission as working to "invigorate the First Amendment by advocating for greater diversity...

 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
Political correctness
Political correctness is a term which denotes language, ideas, policies, and behavior seen as seeking to minimize social and institutional offense in occupational, gender, racial, cultural, sexual orientation, certain other religions, beliefs or ideologies, disability, and age-related contexts,...

". Naureckas criticized these assumptions. He also argued that the book was part of a campaign to justify racism and against welfare and immigration.

Peer review


An early criticism was that Herrnstein and Murray did not submit their work to peer review
Peer review
Peer review is a process of self-regulation by a profession or a process of evaluation involving qualified individuals within the relevant field. Peer review methods are employed to maintain standards, improve performance and provide credibility...

 before publication. Many scholarly reviews of the book arrived later as discussed below. Richard Lynn
Richard Lynn
Richard Lynn is a British Professor Emeritus of Psychology at the University of Ulster who is known for his views on racial and ethnic differences. Lynn argues that there are hereditary differences in intelligence based on race and sex....

 (1999) wrote that "The book has been the subject of several hundred critical reviews, a number of which have been collected in edited volumes".

"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
Mainstream Science on Intelligence
Mainstream Science on Intelligence was a public statement issued by a group of academic researchers in fields allied to intelligence testing that claimed to present those findings widely accepted in the expert community...

" endorsing the views presented in The Bell Curve. The statement was written by psychologist Linda Gottfredson
Linda Gottfredson
Linda Susanne Gottfredson is a professor of educational psychology at the University of Delaware and co-director of the Delaware-Johns Hopkins Project for the Study of Intelligence and Society. Gottfredson's work has been influential in shaping U.S...

 and published in The Wall Street Journal
The Wall Street Journal
The Wall Street Journal is an American English-language international daily newspaper. It is published in New York City by Dow Jones & Company, a division of News Corporation, along with the Asian and European editions of the Journal....

 in 1994 and reprinted in the Intelligence
Intelligence (journal)
Intelligence is a peer-reviewed academic journal of psychology that covers intelligence and psychometrics. It is published by Elsevier and the official journal of the International Society for Intelligence Research.The journal was established in 1977 and the editor in chief is Douglas K. Detterman...

. 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
American Psychological Association
The American Psychological Association is the largest scientific and professional organization of psychologists in the United States. It is the world's largest association of psychologists with around 154,000 members including scientists, educators, clinicians, consultants and students. The APA...

's Board of Scientific Affairs established a special task force to publish an investigative report on the research presented in the book. The final report, titled Intelligence: Knowns and Unknowns
Intelligence: Knowns and Unknowns
Intelligence: Knowns and Unknowns was a 1995 report issued by a Task Force created by the Board of Scientific Affairs of the American Psychological Association.- Background :...

, is available at an academic website. 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.
  • There is little evidence to show that childhood diet influences intelligence except in cases of severe malnutrition
    Malnutrition
    Malnutrition is the condition that results from taking an unbalanced diet in which certain nutrients are lacking, in excess , or in the wrong proportions....

    .
  • 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
Mean
In statistics, mean has two related meanings:* the arithmetic mean .* the expected value of a random variable, which is also called the population 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
Caste
Caste is an elaborate and complex social system that combines elements of endogamy, occupation, culture, social class, tribal affiliation and political power. It should not be confused with race or social class, e.g. members of different castes in one society may belong to the same race, as in India...

 and culture
Culture
Culture is a term that has many different inter-related meanings. For example, in 1952, Alfred Kroeber and Clyde Kluckhohn compiled a list of 164 definitions of "culture" in Culture: A Critical Review of Concepts and Definitions...

 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
American Psychologist
The American Psychologist is the official academic journal of the American Psychological Association. It contains archival documents and articles covering current issues in psychology, the science and practice of psychology, and psychology's contribution to public policy...

, 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
Stephen Jay Gould
Stephen Jay Gould was an American paleontologist, evolutionary biologist, and historian of science. He was also one of the most influential and widely read writers of popular science of his generation....

 (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).
  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, anthropologist C. Loring Brace
C. Loring Brace
C. Loring Brace is an anthropologist at the University of Michigan. He considers the attempt "to introduce a Darwinian outlook into biological anthropology" to be his greatest contribution to the field of anthropology.-Life and work:...

 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.
  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
    Wiktionary
    Wiktionary is a multilingual, web-based project to create a free content dictionary, available in 158 languages...

    , 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
Nobel Prize
The Nobel Prizes are annual international awards bestowed by Scandinavian committees in recognition of cultural and scientific advances. The will of the Swedish chemist Alfred Nobel, the inventor of dynamite, established the prizes in 1895...

 winning economist James Heckman
James Heckman
James Joseph Heckman is an American economist and Nobel laureate. He is the Henry Schultz Distinguished Service Professor of Economics at the University of Chicago, Professor of Science and Society at University College Dublin and a Senior Research Fellow at the American Bar Foundation.Heckman...

 writes that two assumptions made in the book are questionable: that g accounts for correlation
Correlation
In statistics, dependence refers to any statistical relationship between two random variables or two sets of data. Correlation refers to any of a broad class of statistical relationships involving dependence....

 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. Murray argued that this was a straw man
Straw man
A straw man is a component of an argument and is an informal fallacy based on misrepresentation of an opponent's position, twisting his words or by means of [false] assumptions...

 and that the book does not argue that g or IQ are totally immutable or the only factors affecting outcomes.

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
Education
Education in its broadest, general sense is the means through which the aims and habits of a group of people lives on from one generation to the next. Generally, it occurs through any experience that has a formative effect on the way one thinks, feels, or acts...

, the ability of IQ to predict poverty
Poverty
Poverty is the lack of a certain amount of material possessions or money. Absolute poverty or destitution is inability to afford basic human needs, which commonly includes clean and fresh water, nutrition, health care, education, clothing and shelter. About 1.7 billion people are estimated to live...

 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.
Inequality by Design: Cracking the Bell Curve Myth
Inequality by Design: Cracking the Bell Curve Myth is a book by Claude S. Fischer, Michael Hout, Martín Sánchez Jankowski, Samuel R. Lucas, Ann Swidler, and Kim Voss...

, 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.

In August 1995, at the National Bureau of Economic Research
National Bureau of Economic Research
The National Bureau of Economic Research is an American private nonprofit research organization "committed to undertaking and disseminating unbiased economic research among public policymakers, business professionals, and the academic community." The NBER is well known for providing start and end...

 economist
Economist
An economist is a professional in the social science discipline of economics. The individual may also study, develop, and apply theories and concepts from economics and write about economic policy...

 Sanders Korenman and Harvard University
Harvard University
Harvard University is a private Ivy League university located in Cambridge, Massachusetts, United States, established in 1636 by the Massachusetts legislature. Harvard is the oldest institution of higher learning in the United States and the first corporation chartered in the country...

 sociologist Christopher Winship
Christopher Winship
Christopher Winship is Diker-Tishman Professor of sociology at Harvard University, and principal of the Hauser Center for Nonprofit Organizations at Harvard. He is best known for his contributions to quantitative methods in sociology and, since 1995, has served as editor of Sociological Methods...

 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."

One early critical book was The Bell Curve Debate
The Bell Curve Debate
The Bell Curve Debate is a response to The Bell Curve, by Richard J. Herrnstein and Charles Murray. It includes 81 articles by 81 authors including K. Anthony Appiah, Gregg Easterbrook, Howard Gardner, Eugene D. Genovese, Nathan Glazer, Stephen Jay Gould, Bob Herbert, Christopher Hitchens, Irving...

.

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, wage
Wage
A wage is a compensation, usually financial, received by workers in exchange for their labor.Compensation in terms of wages is given to workers and compensation in terms of salary is given to employees...

s and meritocracy
Meritocracy
Meritocracy, in the first, most administrative sense, is a system of government or other administration wherein appointments and responsibilities are objectively assigned to individuals based upon their "merits", namely intelligence, credentials, and education, determined through evaluations or...

, pathways to racial and ethnic inequalities in health
Health
Health is the level of functional or metabolic efficiency of a living being. In humans, it is the general condition of a person's mind, body and spirit, usually meaning to be free from illness, injury or pain...

, and the question of public policy
Policy
A policy is typically described as a principle or rule to guide decisions and achieve rational outcome. The term is not normally used to denote what is actually done, this is normally referred to as either procedure or protocol...

. 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.

William J. Matthews writes that part of The Bell Curves analysis is based on the AFQT "which is not an IQ test but designed to predict performance of certain criterion variables". 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.


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.

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.

Min-Hsiung Huang and Robert M. Hauser
Robert M. Hauser
Robert Mason Hauser is an American sociologist. He is currently the Vilas Research and Samuel F. Stouffer professor of sociology at the University of Wisconsin–Madison, where has served as director of the Institute for Research on Poverty and currently is director of the Center for Demography...

 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."

In 1972, Noam Chomsky
Noam Chomsky
Avram Noam Chomsky is an American linguist, philosopher, cognitive scientist, and activist. He is an Institute Professor and Professor in the Department of Linguistics & Philosophy at MIT, where he has worked for over 50 years. Chomsky has been described as the "father of modern linguistics" and...

 questioned Herrnstein's idea that society was developing towards a meritocracy
Meritocracy
Meritocracy, in the first, most administrative sense, is a system of government or other administration wherein appointments and responsibilities are objectively assigned to individuals based upon their "merits", namely intelligence, credentials, and education, determined through evaluations or...

. 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.

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."


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
Thomas Sowell
Thomas Sowell is an American economist, social theorist, political philosopher, and author. A National Humanities Medal winner, he advocates laissez-faire economics and writes from a libertarian perspective...

 criticized the book's conclusions about race and the malleability of IQ, writing:
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.

Columnist Bob Herbert
Bob Herbert
Robert “Bob” Herbert is an American journalist op-ed columnist who wrote for The New York Times. His column was syndicated to other newspapers around the country. Herbert frequently writes on poverty, the Iraq war, racism and American political apathy towards race issues...

, writing for The New York Times
The New York Times
The New York Times is an American daily newspaper founded and continuously published in New York City since 1851. The New York Times has won 106 Pulitzer Prizes, the most of any news organization...

, 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
Nigger
Nigger is a noun in the English language, most notable for its usage in a pejorative context to refer to black people , and also as an informal slang term, among other contexts. It is a common ethnic slur...

."

One prominent critic of The Bell Curve was the late Stephen Jay Gould
Stephen Jay Gould
Stephen Jay Gould was an American paleontologist, evolutionary biologist, and historian of science. He was also one of the most influential and widely read writers of popular science of his generation....

, who in 1996 released a revised and expanded edition of his 1981 book The Mismeasure of Man
The Mismeasure of Man
The Mismeasure of Man , by Stephen Jay Gould, is a history and critique of the statistical methods and cultural motivations underlying biological determinism, the belief that “the social and economic differences between human groups — primarily races, classes, and sexes — arise from inherited,...

 intended to more directly refute many of The Bell Curves claims regarding race and intelligence
Race and intelligence
The connection between race and intelligence has been a subject of debate in both popular science and academic research since the inception of intelligence testing in the early 20th century...

. 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.

Melvin Konner
Melvin Konner
Melvin Konner, MD, PhD, is the Samuel Candler Dobbs Professor of Anthropology and Associate Professor of Psychiatry and Neurology at Emory University. He studied at Brooklyn College , CUNY , where he met Marjorie Shostak, whom he later married and with whom he had three children. He earned his PhD...

, professor of anthropology
Anthropology
Anthropology is the study of humanity. It has origins in the humanities, the natural sciences, and the social sciences. The term "anthropology" is from the Greek anthrōpos , "man", understood to mean mankind or humanity, and -logia , "discourse" or "study", and was first used in 1501 by German...

 and associate professor of psychiatry
Psychiatry
Psychiatry is the medical specialty devoted to the study and treatment of mental disorders. These mental disorders include various affective, behavioural, cognitive and perceptual abnormalities...

 and neurology
Neurology
Neurology is a medical specialty dealing with disorders of the nervous system. Specifically, it deals with the diagnosis and treatment of all categories of disease involving the central, peripheral, and autonomic nervous systems, including their coverings, blood vessels, and all effector tissue,...

 at Emory University
Emory University
Emory University is a private research university in metropolitan Atlanta, located in the Druid Hills section of unincorporated DeKalb County, Georgia, United States. The university was founded as Emory College in 1836 in Oxford, Georgia by a small group of Methodists and was named in honor of...

, 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
Wiktionary
Wiktionary is a multilingual, web-based project to create a free content dictionary, available in 158 languages...

 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.


Noam Chomsky
Noam Chomsky
Avram Noam Chomsky is an American linguist, philosopher, cognitive scientist, and activist. He is an Institute Professor and Professor in the Department of Linguistics & Philosophy at MIT, where he has worked for over 50 years. Chomsky has been described as the "father of modern linguistics" and...

 in 1972 in an earlier debate with Herrnstein argued that even if there is a correlation between race and intelligence
Race and intelligence
The connection between race and intelligence has been a subject of debate in both popular science and academic research since the inception of intelligence testing in the early 20th century...

, 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].

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
Fertility and intelligence
Fertility and intelligence research investigates the relationship between fertility and intelligence. Demographic studies have indicated that in humans, fertility and intelligence tend to be inversely correlated, that is to say, the more intelligent, as measured by IQ tests, exhibit a lower total...

 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
American Enterprise Institute
The American Enterprise Institute for Public Policy Research is a conservative think tank founded in 1943. Its stated mission is "to defend the principles and improve the institutions of American freedom and democratic capitalism—limited government, private enterprise, individual liberty and...

 will rapidly rise. The problem is solved;


Rutledge M. Dennis suggests that through soundbite
Soundbite
In film and broadcasting, a sound bite is a very short piece of a speech taken from a longer speech or an interview in which someone with authority or the average "man on the street" says something which is considered by those who edit the speech or interview to be the most important point...

s 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."

Critic Charles Lane pointed out that 17 of the researchers whose work is referenced by the book have also contributed to Mankind Quarterly
Mankind Quarterly
The Mankind Quarterly is a peer-reviewed academic journal dedicated to physical and cultural anthropology and is currently published by the Council for Social and Economic Studies in Washington, D.C. It contains articles on human evolution, intelligence, ethnography, linguistics, mythology,...

, a journal of anthropology founded in 1960 in Edinburgh, which has been viewed as supporting the theory of the genetic superiority of the whites.

In his book The Bell Curve Wars: Race, Intelligence, and the Future of America
The Bell Curve Wars: Race, Intelligence, and the Future of America
The Bell Curve Wars: Race, Intelligence, and the Future of America is a reaction to The Bell Curve:Intelligence and Class Structure in American Life by Richard J. Herrnstein and Charles Murray...

, 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".

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. Critics have noted much of the work referenced by the Bell Curve was funded by the Pioneer Fund
Pioneer Fund
The Pioneer Fund is an American non-profit foundation established in 1937 "to advance the scientific study of heredity and human differences." Currently headed by psychology professor J. Philippe Rushton, the fund states that it focuses on projects it perceives will not be easily funded due to...

, which aims to advance the scientific study of heredity and human differences, and has been accused of promoting scientific racism
Scientific racism
Scientific racism is the use of scientific techniques and hypotheses to sanction the belief in racial superiority or racism.This is not the same as using scientific findings and the scientific method to investigate differences among the humans and argue that there are races...

.

Evolutionary biologist Joseph L. Graves
Joseph L. Graves
Joseph L. Graves, Jr. is Associate Dean for Research and Professor of Biological Studies at the Joint School for Nanoscience and Nanoengineering which is jointly administered by North Carolina Agricultural and Technical State University and UNC Greensboro...

 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
Scientific racism
Scientific racism is the use of scientific techniques and hypotheses to sanction the belief in racial superiority or racism.This is not the same as using scientific findings and the scientific method to investigate differences among the humans and argue that there are races...

:
  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.

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.


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 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.

External links


Responses to The Bell Curve