For Whom the Bell Curve Really Tolls:
A tendentious tome abuses science to promote far-right policies

Rarely do 800-page books crammed with graphs reach best-seller lists. "The Bell Curve," an inflammatory treatise about class, intelligence and race by the late Richard J. Herrnstein, a psychology professor at Harvard University who died last September, and political scientist Charles Murray of the American Enterprise Institute, is an exception. The book's deeply pessimistic analysis of U.S. social woes, together with its conservative policy prescriptions, has hit a nerve.

Publishing "The Bell Curve" may have been a calculated political move on the part of its authors. As the country lurches to the right, many people will be seduced by the text's academic trappings and scientific tone into believing its arguments and political inferences well supported. Those readers should think again.

"The Bell Curve" depicts a frightening future in which, absent strong corrective measures, a "cognitive elite" will live in guarded enclaves distant from the dull masses. Opportunities for the underclass will become limited as tolerance evaporates. Strict policing will be widely accepted, and racial hostility will likely spread. The least intelligent denizens of this dystopia will be consigned to a "high-tech and more lavish version of the Indian reservation."

This apocalyptic vision is presented as the consequence of unpalatable, undeniable "facts" about inheritance and intelligence. But the thesis rests on curiously twisted logic. Its authors have been highly selective in the evidence they present and in their interpretation of ambiguous statistics. The work is "a string of half-truths," states Christopher Jencks, a sociologist at Northwestern University.

The arguments stem from the same tradition of biological determinism that led, not so long ago, to compulsory sterilizations in the U.S. and genocide elsewhere. The notion is that individuals' characteristics are both essentially fixed by inheritance and immune to alteration by the environment. Efforts to help those who are unfortunate by reason of their genes are unlikely to be rewarded. Solutions, therefore, should include those Murray has long advocated: abolish welfare, reduce affirmative action and simplify criminal law.

Herrnstein and Murray produce data suggesting that intelligence--as assessed by a high IQ score--is increasingly important to economic success. They also argue that people who have low scores--including disproportionate numbers of blacks--are more likely than others are to fall prey to social ills. The two accept evidence from studies of twins reared apart that there is a large heritable component to IQ scores: they estimate it to be 60 percent. The writers declare themselves agnostic on the question of whether racial differences in IQ scores are genetic, although they are clearly inclined to favor that possibility.

Herrnstein and Murray countenance that just because a trait has a heritable origin does not mean it is unchangeable. Nearsightedness is one example of an inherited, modifiable condition. But they decide, on the basis of a questionable look at the data, that "an inexpensive, reliable method of raising IQ is not available." This conclusion is used to justify an attack on programs aimed at helping society's most vulnerable: the authors prefer to let the genetically disadvantaged find their own level. Evidence that does not accord with Herrnstein and Murray's way of thinking--such as the observation that IQ scores worldwide are slowly increasing--is acknowledged then ignored.

Leaving aside the substantial and unresolved issue of whether a single number can adequately summarize mental performance, "The Bell Curve" plays fast and loose with statistics in several ways. According to Arthur Goldberger, an econometrician at the University of Wisconsin who has studied genetics and IQ, the book exaggerates the ability of IQ to predict job performance. Herrnstein and Murray assert that scores have an impressive "validity" of about 0.4 in such predictions. They report that the Armed Forces Qualification Test, an IQ surrogate, has a validity of 0.62 at anticipating the success of training for mechanical jobs. Yet many of the measures used to assess validity include supervisors' ratings, which are subject to bias, Goldberger notes. Furthermore, the validities that the duo see as so revealing are, in fact, hypothetical quantities that no employer would expect to find in prospective employees. "It's really bad stuff," Goldberger says.

Other correlations that the writers establish between social ills and low IQ scores are equally suspect. Herrnstein and Murray put great weight on comparisons between the ability of IQ scores and parental socioeconomic status to predict what will happen to young people. Yet the measures of socioeconomic status they use cannot ensure that homes are equally stimulating. The point is crucial because numerous studies have demonstrated that early childhood surroundings have a large role in molding IQ scores--certainly more studies than have indicated a significant role for heredity. Consequently, conclusions about the dominance of IQ cannot be taken at face value. Leon Kamin, a psychologist at Northeastern University and well-known critic of research on intelligence, maintains that interactions between genes and environment make attempts to weigh nature against nurture "meaningless."

Herrnstein and Murray's hereditarian bias is also obvious in their account of a study of 100 children from varying ethnic backgrounds who were adopted into white families. The study got under way in the 1970s. At age seven, the black and interracial children scored an average of 106 on IQ tests--considerably better than the national average of black children and close to levels scored by white children. A decade later researchers Sandra Scarr of the University of Virginia and Richard A. Weinberg of the University of Minnesota found that the IQs of the black children had declined to 89, whereas those of white adoptees had fallen from 112 to 106.

Scarr and Weinberg concluded that racially based discrimination at school probably explained the drop in the black youngsters' scores. Jencks agrees: "The results are perfectly consistent with the difference being due to something in the early home environment and, for older kids, their experience in school." But Herrnstein and Murray interpret the findings differently: "Whatever the environmental impact may have been, it cannot have been large."

"The Bell Curve's" most egregious failing, however, may be its bleak assessment of educational efforts to improve the intellectual performance of children from deprived backgrounds. Herrnstein and Murray cast a jaundiced eye over Head Start and other more intensive efforts for at-risk youngsters--projects that have been claimed to produce long-lasting gains in IQ, a possibility that would not square well with biological determinist thought. Herrnstein and Murray downplay such results, noting that such interventions are too expensive to be widely used. The only one they are enthusiastic about is adoption, which, paradoxically, they accept as having a clearly positive effect on IQ. "Their treatment of intervention wouldn't be accepted by an academic journal--it's that bad," exclaims Richard Nisbett, a psychology professor at the University of Michigan. "I'm distressed by the extent to which people assume [Murray] is playing by the rules."

Jencks is also unhappy with the book's conclusions about education. "Herrnstein and Murray are saying Head Start didn't have a profound effect. But that doesn't tell us that we couldn't do a lot better if we had a different society," he says. "In Japan, for example, children learn more math than they do in the U.S. because everybody there agrees math is important."

Scarr, who accepts a substantial role for heredity in individual IQ differences, insists that efforts to boost intellectual functioning in disadvantaged youth can deliver results. "There's no question that rescuing children from desperately awful circumstances will improve their performance," she notes.

Scarr also points out that ameliorating a child's environment may reduce social problems, regardless of its effect on IQ. "The low-IQ group deserves a lot more support than it is getting," she argues. "Other societies manage not to have the same levels of social ills as we do." Edward F. Zigler, a prominent educational psychologist at Yale University, asserts that "in terms of everyday social competence, we have overwhelming evidence that high-quality early education is beneficial."

Therein lies the fatal flaw in Herrnstein and Murray's harsh reasoning. Even though boosting IQ scores may be difficult and expensive, providing education can help individuals in other ways. That fact, not IQ scores, is what policy should be concerned with. "The Bell Curve's" fixation on IQ as the best statistical predictor of a life's fortunes is a myopic one. Science does not deny the benefits of a nurturing environment and a helping hand.--Tim Beardsley

SCIENTIFIC AMERICAN January 1995 Volume 272 Number 1 Page 14

Scientific American (ISSN 0036-8733), published monthly by Scientific American, Inc., 415 Madison Avenue, New York, N.Y. 10017-1111. Copyright 1994 by Scientific American, Inc. All rights reserved. Except for one-time personal use, no part of any issue may be reproduced by any mechanical, photographic or electronic process, or in the form of a phonographic recording, nor may it be stored in a retrieval system, transmitted or otherwise copied for public or private use without written permission of the publisher. For information regarding back issues, reprints or permissions, E-mail