Case Study Two: Smart Rich People

A key assertion of The Bell Curve is that high intelligence is increasingly valuable in the marketplace, and that the highly intelligent are increasingly powerful and prosperous. But the data presented in support of this are surprisingly weak.

One example is corporate executives. Herrnstein and Murray cite "common sense and circumstantial evidence" in support of the proposition that more and more people in "the upper echelons of large businesses tend to have high IQs." The only piece of supporting data they cite is a 20-year-old story in Fortune saying that 40 percent of corporate CEOs have law degrees or MBAs, "fields of study that are highly screened for intelligence," according to Herrnstein and Murray. This is pretty thin gruel. Of course, they have no access to the IQ scores of CEOs today or at any time in the past.

Then they produce this crackpot calculation: They assume that there are 11 million people with IQs above 120 in the labor force. Then they say they have "reason to believe" (no proof) that half of the 7.3 million people in the professions have IQs of over 120. This leaves 7.4 million supersmart people "unaccounted for." Because there are 12.9 million people in executive, administrative, and managerial jobs; and because most of these people rose in their companies and graduated from college; and because the mean IQ of college graduates "was estimated at about 115 in 1972"; we have "startlingly little room to maneuver": Most of the 7.4 million missing geniuses must be business executives. In fact, "One could easily make the case that the figure is in the neighborhood of 70 to 80 per cent." This is, of course, a pure guess based on the unproved assumption that all high-IQ people have fancy jobs, and on no information at all about the IQs of executives. But in The Bell Curve, quod erat demonstrandum.

Another example: A 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. Robert Hauser and his colleague Min-Hsiung Huang went back to the data. They report, "We have not been able to reproduce this display from the sources given by Herrnstein and Murray," and, "our estimates appear to fall 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."

One more example: A section of The Bell Curve is devoted to showing "that an important statistical link between IQ and job performance does in fact exist." Herrnstein and Murray say that "in many ways the most satisfactory" data on this come from military intelligence tests. But when you read along, you find that what the IQ scores predict is grades in military schools, which they treat as the same thing as job performance. IQ critics have always conceded that what the test is best at predicting is grades in school. But they need convincing that all this is connected to later job performance. The Bell Curve gets around the issue by simply declaring grades to be job performance.

Hauser and another colleague, Wendy Carter, devised an elegant little test of the cognitive-elite thesis. From a 20-year study of 13,000 people who had been given a simple 10-question IQ test, they extracted all the people who had gotten perfect scores (6 percent) and estimated their chances over time of winding up in elite occupations. They report that top scorers are indeed more likely to end up in elite occupations but, if anything, that likelihood has declined slightly over the years. Hauser and Carter add that social mobility between generations, an area where there is plenty of data (undiscussed in The Bell Curve), has been consistently increasing, although by Herrnstein and Murray's logic, mobility ought to have increased dramatically during the period of the "invisible migration," and then declined dramatically as the hereditary cognitive elite settled into the throne.

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