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Last week, the president of Virginia Tech, Tim Sands, published an “open letter to the Virginia Tech community” defending lectures delivered by deplorable people like me (I’m speaking on the themes of Coming Apart on March 25). Bravo for President Sands’s defense of intellectual freedom. But I confess that I was not entirely satisfied with his characterization of my work. So I’m writing an open letter of my own.
Dear Virginia Tech community,
Since President Sands has just published an open letter making a serious allegation against me, it seems appropriate to respond. The allegation: “Dr. Murray is well known for his controversial and largely discredited work linking measures of intelligence to heredity, and specifically to race and ethnicity — a flawed socioeconomic theory that has been used by some to justify fascism, racism and eugenics.”
Let me make an allegation of my own. President Sands is unfamiliar either with the actual content of The Bell Curve — the book I wrote with Richard J. Herrnstein to which he alludes — or with the state of knowledge in psychometrics.
I should begin by pointing out that the topic of the The Bell Curve was not race, but, as the book’s subtitle says, “Intelligence and Class Structure in American Life.” Our thesis was that over the last half of the 20th century, American society has become cognitively stratified. At the beginning of the penultimate chapter, Herrnstein and I summarized our message:
Predicting the course of society is chancy, but certain tendencies seem strong enough to worry about:
- An increasingly isolated cognitive elite.
- A merging of the cognitive elite with the affluent.
- A deteriorating quality of life for people at the bottom end of the cognitive distribution.
Unchecked, these trends will lead the U.S. toward something resembling a caste society, with the underclass mired ever more firmly at the bottom and the cognitive elite ever more firmly anchored at the top, restructuring the rules of society so that it becomes harder and harder for them to lose. [p. 509].
It is obvious that these conclusions have not been discredited in the twenty-two years since they were written. They may be more accurately described as prescient.
Now to the substance of President Sands’s allegation.
The heritability of intelligence
Richard Herrnstein and I wrote that cognitive ability as measured by IQ tests is heritable, somewhere in the range of 40% to 80% [pp. 105–110], and that heritability tends to rise as people get older. This was not a scientifically controversial statement when we wrote it; that President Sands thinks it has been discredited as of 2016 is amazing.
You needn’t take my word for it. In the wake of the uproar over The Bell Curve, the American Psychological Association (APA) assembled a Task Force on Intelligence consisting of eleven of the most distinguished psychometricians in the United States. Their report, titled “Intelligence: Knowns and Unknowns,” was published in the February 1996 issue of the APA’s peer-reviewed journal, American Psychologist. Regarding the magnitude of heritability (represented by h2), here is the Task Force’s relevant paragraph. For purposes of readability, I have omitted the citations embedded in the original paragraph:
If one simply combines all available correlations in a single analysis, the heritability (h2) works out to about .50 and the between-family variance (c2) to about .25. These overall figures are misleading, however, because most of the relevant studies have been done with children. We now know that the heritability of IQ changes with age: h2 goes up and c2 goes down from infancy to adulthood. In childhood h2 and c2 for IQ are of the order of .45 and .35; by late adolescence h2 is around .75 and c2 is quite low (zero in some studies) [p. 85].
The position we took on heritability was squarely within the consensus state of knowledge. Since The Bell Curve was published, the range of estimates has narrowed somewhat, tending toward modestly higher estimates of heritability.
Intelligence and race
There’s no doubt that discussing intelligence and race was asking for trouble in 1994, as it still is in 2016. But that’s for political reasons, not scientific ones.
There’s no doubt that discussing intelligence and race was asking for trouble in 1994, as it still is in 2016. But that’s for political reasons, not scientific ones. Once again, the state of knowledge about the basics is not particularly controversial. The mean scores for all kinds of mental tests vary by ethnicity. No one familiar with the data disputes that most elemental statement. Regarding the most sensitive difference, between Blacks and Whites, Herrnstein and I followed the usual estimate of one standard deviation (15 IQ points), but pointed out that the magnitude varied depending on the test, sample, and where and how it was administered. What did the APA Task Force conclude? “Although studies using different tests and samples yield a range of results, the Black mean is typically about one standard deviation (about 15 points) below that of Whites. The difference is largest on those tests (verbal or nonverbal) that best represent the general intelligence factor g” [p. 93].
Is the Black/White differential diminishing? In The Bell Curve, we discussed at length the evidence that the Black/White differential has narrowed [pp. 289–295], concluding that “The answer is yes with (as usual) some qualifications.” The Task Force’s treatment of the question paralleled ours, concluding with “[l]arger and more definitive studies are needed before this trend can be regarded as established” [p. 93].
Can the Black/White differential be explained by test bias? In a long discussion [pp. 280–286], Herrnstein and I presented the massive evidence that the predictive validity of mental tests is similar for Blacks and Whites and that cultural bias in the test items or their administration do not explain the Black/White differential. The Task Force’s conclusions regarding predictive validity: “Considered as predictors of future performance, the tests do not seem to be biased against African Americans” [p. 93]. Regarding cultural bias and testing conditions: “Controlled studies [of these potential sources of bias] have shown, however, that none of them contributes substantially to the Black/White differential under discussion here” [p. 94].
Can the Black/White differential be explained by socioeconomic status? We pointed out that the question has two answers: Statistically controlling for socioeconomic status (SES) narrows the gap. But the gap does not narrow as SES goes up — i.e., measured in standard deviations, the differential between Blacks and Whites with high SES is not narrower than the differential between those with low SES [pp. 286–289]. Here’s the APA Task Force on this topic:
Several considerations suggest that [SES] cannot be the whole explanation. For one thing, the Black/White differential in test scores is not eliminated when groups or individuals are matched for SES. Moreover, the data reviewed in Section 4 suggest that—if we exclude extreme conditions—nutrition and other biological factors that may vary with SES account for relatively little of the variance in such scores [p. 94].
The notion that Herrnstein and I made claims about ethnic differences in IQ that have been scientifically rejected is simply wrong.
And so on. The notion that Herrnstein and I made claims about ethnic differences in IQ that have been scientifically rejected is simply wrong. We deliberately remained well within the mainstream of what was confidently known when we wrote. None of those descriptions have changed much in the subsequent twenty-two years, except to be reinforced as more has been learned. I have no idea what countervailing evidence President Sands could have in mind.
At this point, some readers may be saying to themselves, “But wasn’t The Bell Curve the book that tried to prove blacks were genetically inferior to whites?” I gather that was President Sands’ impression as well. It has no basis in fact. Knowing that people are preoccupied with genes and race (it was always the first topic that came up when we told people we were writing a book about IQ), Herrnstein and I offered a seventeen-page discussion of genes, race, and IQ [pp. 295–311]. The first five pages were devoted to explaining the context of the issue — why, for example, the heritability of IQ among humans does not necessarily mean that differences between groups are also heritable. Four pages were devoted to the technical literature arguing that genes were implicated in the Black/White differential. Eight pages were devoted to arguments that the causes were environmental. Then we wrote:
If the reader is now convinced that either the genetic or environmental explanation has won out to the exclusion of the other, we have not done a sufficiently good job of presenting one side or the other. It seems highly likely to us that both genes and the environment have something to do with racial differences. What might the mix be? We are resolutely agnostic on that issue; as far as we can determine, the evidence does not yet justify an estimate. [p. 311].
That’s it—the sum total of every wild-eyed claim that The Bell Curve makes about genes and race. There’s nothing else. Herrnstein and I were guilty of refusing to say that the evidence justified a conclusion that the differential had to be entirely environmental. On this issue, I have a minor quibble with the APA Task Force, which wrote “There is not much direct evidence on [a genetic component], but what little there is fails to support the genetic hypothesis” [p. 95]. Actually there was no direct evidence at all as of the mid-1990s, but the Task Force chose not to mention a considerable body of indirect evidence that did in fact support the genetic hypothesis. No matter. The Task Force did not reject the possibility of a genetic component. As of 2016, geneticists are within a few years of knowing the answer for sure, and I am content to wait for their findings.
But I cannot leave the issue of genes without mentioning how strongly Herrnstein and I rejected the importance of whether genes are involved. This passage from The Bell Curve reveals how very, very different the book is from the characterization of it that has become so widespread:
In sum: If tomorrow you knew beyond a shadow of a doubt that all the cognitive differences between races were 100 percent genetic in origin, nothing of any significance should change. The knowledge would give you no reason to treat individuals differently than if ethnic differences were 100 percent environmental. By the same token, knowing that the differences are 100 percent environmental in origin would not suggest a single program or policy that is not already being tried. It would justify no optimism about the time it will take to narrow the existing gaps. It would not even justify confidence that genetically based differences will not be upon us within a few generations. The impulse to think that environmental sources of difference are less threatening than genetic ones is natural but illusory.
In any case, you are not going to learn tomorrow that all the cognitive differences between races are 100 percent genetic in origin, because the scientific state of knowledge, unfinished as it is, already gives ample evidence that environment is part of the story. But the evidence eventually may become unequivocal that genes are also part of the story. We are worried that the elite wisdom on this issue, for years almost hysterically in denial about that possibility, will snap too far in the other direction. It is possible to face all the facts on ethnic and race differences on intelligence and not run screaming from the room. That is the essential message [pp. 314-315].
I have been reluctant to spend so much space discussing The Bell Curve’s treatment of race and intelligence because it was such an ancillary topic in the book. Focusing on it in this letter has probably made it sound as if it was as important as President Sands’s open letter implied.
But I had to do it. For two decades, I have had to put up with misrepresentations of The Bell Curve. It is annoying. After so long, when so many of the book’s main arguments have been so dramatically vindicated by events, and when our presentations of the meaning and role of IQ have been so steadily reinforced by subsequent research in the social sciences, not to mention developments in neuroscience and genetics, President Sands’s casual accusation that our work has been “largely discredited” was especially exasperating. The president of a distinguished university should take more care.
It is in that context that I came to the end of President Sands’s indictment, accusing me of promulgating “a flawed socioeconomic theory that has been used by some to justify fascism, racism and eugenics.” At that point, President Sands went beyond the kind of statement that merely reflects his unfamiliarity with The Bell Curve and/or psychometrics. He engaged in intellectual McCarthyism.
See you next week.
WH Brady Scholar
American Enterprise Institute
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