The debate about the relationship between intelligence and race rages on in the wake of some controversial remarks made by Dr. James Watson, published in the Sunday Times of London in October. Strangely absent in these arguments, which are based on I.Q. research, is a discussion of what the “Intelligence Quotient” is supposed to measure.

In the latest salvo, The New York Times published a fairly solid op-ed by Richard E. Nisbett last Sunday, titled “All Brains Are the Same Color.” A professor of psychology at the University of Michigan, Nisbett argues that when it comes to intelligence, nurture trumps nature:

James Flynn, a philosopher and I.Q. researcher in New Zealand, has established that in the Western world as a whole, I.Q. increased markedly from 1947 to 2002. In the United States alone, it went up by 18 points. Our genes could not have changed enough over such a brief period to account for the shift; it must have been the result of powerful social factors.

Nisbett’s arguments are worth considering, as are similar ones made by Malcolm Gladwell in this week’s New Yorker. Both come as salient responses to William Saletan’s three-including an apology, four-part series in Slate.

Saletan took the side of those arguing that I.Q., and therefore intelligence, does in fact have a racial component. He cites a number of studies that would appear to validate this standpoint-that is, if the data were accurate, and properly interpreted. Gladwell skewers Saletan for, “Drawing heavily on the work of J. Philippe Rushton-a psychologist who specializes in comparing the circumference of what he calls the Negroid brain with the length of the Negroid penis.” Ouch.

What’s missing from this dust-up, however, is that I.Q is an imperfect measure of intelligence, thus rendering many of the arguments about its link to race even more dubious. There are a variety of different IQ tests and scoring methods out there; those scores can be standardized using a typical bell curve distribution, but the bell curve itself opens up another box of questions and considerations, such as the difficulty of factoring in extremely low and extremely high scores. Other quibbles with I.Q. include the possibility that it can change over the course of person’s life, and that it does not measure creativity. At the root of these concerns is an even more fundamental question-not what is I.Q., a unit of measure, but what is intelligence?

In fact, someone has recently brought up the problems associated with defining and testing intelligence. In a New York Times column in September, David Brooks explained “the diminishing influence of I.Q.” Unfortunately, the piece ran a month before Watson made his provocative comments that blacks tend to have lower intelligence, and Brooks’s column was overlooked once the ruckus began. It’s too bad, because his argument is strong: he didn’t just question the validity of I.Q. testing, he argued that there is a lack of consensus about what defines intelligence.

In 1996, a task force of the American Psychological Association released a report on intelligence and intelligence testing. The introduction supports the idea that, although measures such as I.Q. are not without value, there is a definite lack of consensus in this field of science:

Indeed, when two dozen prominent theorists were recently asked to define intelligence, they gave two dozen somewhat different definitions (Stemberg & Detterman, 1986). Such disagreements are not cause for dismay. Scientific research rarely begins with fully agreed definitions, though it may eventually lead to them.

In The New Yorker, Gladwell at least touches on the idea that I.Q. “measures not so much how smart we are as how modern we are.” He notes that changes in verbal intelligence scores (one component of overall I.Q in some tests) have a lot to do with what test-takers identify as the primary similarity between two objects or animals-and how one’s society and culture play a distinguishing role in what the “correct” answer is. (Do “dog” and “rabbit” go together because they are both mammals, for instance, or because one is used to hunt the other?)

Russ Juskalian is a contributor to The Observatory and a freelance writer.