The idea of intelligence —that human beings possess, to varying degrees, an innate and universal ability to learn—has taken a beating in recent decades. Ever since Stephen J. Gould's Mismeasurement of Man (Norton, 1981) and Howard Gardner's Frames of Mind: The Theory of Multiple Intelligences (Basic Books, 1983), the notion of a single intelligence entity, typically called "g," has come under assault. That is unfortunate.
A number of scholars, including L.L. Thurstone and more recently Robert J. Sternberg, have argued that intelligence has been defined too narrowly. But Gardner, a professor of cognition and education at the Harvard Graduate School of Education, who won a prestigious MacArthur Foundation "genius award" in 1981, has had enormous influence, particularly in our schools.
Briefly, he has posited that our intellectual abilities are divided among at least eight abilities: verbal-linguistic, logical-mathematical, visual-spatial, bodily-kinesthetic, naturalistic, musical, interpersonal, and intrapersonal. The appealing elements of the theory are numerous.
It's "cool," to start with: The list-like format has great attraction for introductory psychology and education classes. It also seems to jibe well with the common observation that individuals have particular talents. More important, especially for education, it implicitly (although perhaps unintentionally on Gardner's part) promises that each child has strengths as well as weaknesses. With eight separate intelligences, the odds seem good that every child will be intelligent in one of those realms. After all, it's not called the theory of multiple stupidities.
Multiple intelligences put every child on an equal footing, granting the hope of identical value in an ostensible meritocracy. The theory fits well with a number of the assumptions that have dominated educational philosophy for years. The movements that took flower in the mid-20th century have argued for the essential sameness of all healthy human beings and for a policy of social justice that treats all people the same. Above all, many educators have adhered to the social construction of reality—the idea that redefining the way we treat children will redefine their abilities and future successes. (Perhaps that's what leads some parents to put their faith in "Baby Einstein" videos: the hope that a little nurturing television will send their kids to Harvard.) It would be difficult to overestimate the influence of Gardner's work, both in repudiating that elitist, unfair concept of "g" and in guiding thought in psychology as it applies to education.
The only problem, with all respect to Gardner: There probably is just a single intelligence or capacity to learn, not multiple ones devoted to independent tasks. To varying degrees, some individuals have this capacity, and others do not. To be sure, there is much debate about Gardner's theory in the literature, with contenders for and against. Nonetheless, empirical evidence has not been robust. While the theory sounds nice (perhaps because it sounds nice), it is more intuitive than empirical. In other words, the eight intelligences are based more on philosophy than on data.
Of course, nothing is ever cut and dried when it comes to the social sciences. Gardner and the psychologist Lynn Waterhouse engaged in a lively debate in the journal Educational Psychologist in 2006. While the exchange was informative, empirical evidence to support multiple intelligences was largely absent. As Waterhouse put it, the theory is "persisting without adequate evidence"—and was likely to continue to do so, she added, because of the "good news stories" it provides. By contrast, a wealth of evidence supports the existence of "g," which, contrary to the claims (or wishes) of some people, remains a strong predictor of academic performance, job performance—particularly in highly technical careers or those requiring decision making—and other markers of "success."
Another issue with the theory of multiple intelligences is that too many of the categories correlate too highly with one another to be separate intelligences. Cognitive performance on skills related to verbal-linguistic, logical-mathematical, and visual-spatial tasks, as well as many memory tasks, tends to be highly related. In other words, it goes back to "g."
The remaining intelligences have nothing to do with intelligence or cognitive skills per se, but rather represent personal interests (for example, musical represents an affinity for music; naturalistic, an affinity for biology or geology) or personality traits (interpersonal or intrapersonal skills, which correspond best to the related concept of emotional intelligence). And even those interest areas may be enhanced by "g." Only bodily-kinesthetic—the ability to manipulate one's own body with dexterity—may truly represent a separate cognitive ability, probably stemming from cerebellar activity involved in fine motor control. It may be better represented as a neurophysiological trait than as intelligence. Even for related activities—dancing, for instance—having at least a modicum of "g" is still going to be necessary to learn, say, complex dance choreography.
Finally, as Waterhouse noted in her exchange with Gardner, the theory of multiple intelligences has little value for clinical testing of intelligence or the prediction of future performance. "G" alone is highly predictive of both academic and work success. The other intelligences, or whatever they are, add very little.
Part of the confusion that has allowed the theory to survive long past the stage of empirical disrepute is the irascible debate regarding what intelligence is in the first place. Intelligence is among the most stable of psychological constructs. It is as possible to define it both operationally and conceptually as it is for almost any other psychological variable, although that might not be saying much. At worst, intelligence is like pornography: I may not be able to define it to the satisfaction of all, but I sure know it when I see it (or, in the case of intelligence, when I come across its absence). At the optimistic extreme, a reasonable definition of intelligence is not hard to come by. Intelligence: An innate cognitive ability that powers learning. Perfect? No. But that's basically it.
Aren't there plenty of Ph.D.'s who can't fix their cars? Sure, but the majority of them could learn if they were so inclined. An individual with low "g" is going to struggle at both book learning and auto repair (although perhaps car mechanics would prove more manageable than literary theory or quantum physics). In other words, individuals high in "g" are going to be able to learn a wider range of activities with greater ease than individuals low in "g". The "g" that assisted our hominid forebears in learning the skills of hunting, gathering, and toolmaking is the same "g" that gives gifted/talented students an advantage in calculus. Of course, one person can't learn everything, so some folks pick, say, European history over Math Without Numbers (or whatever the rage is in mathematics these days). The theory of multiple intelligences fundamentally conflates intelligence and motivation. It's a fatal flaw. Motivation is certainly important, and it works alongside intelligence to produce results. However, having the raw biological machinery of intelligence is simply irreplaceable.
Perhaps in a naïve effort to deny that inconvenient truth, the debate about intelligence has become largely political, at times even facetious. Intelligence certainly is not the only predictor of success in work or in school, college, or scholarship, but it's as strong as any. Unfortunately, it's also largely genetic. Social justice, treating people the same, bringing out their best abilities are all worthy ideals. Yet we must be cautious when ideals conflict with reality. The world in which we live has no obligation to be politically correct. And it is not politically correct to say that one person is, well, simply more talented than another.
Despite some naysayers (think of Richard E. Nisbett's Intelligence and How to Get It: Why Schools and Cultures Count, published this year by Norton), evidence from behavioral-genetics studies has long shown that environment plays a much smaller role than inheritance in the development of intelligence. And that's defining "environment" so broadly that it includes head injuries, infections like encephalitis, malnourishment, and neglect. You've probably heard of those studies of twins raised separately who show similar intellectual abilities when reunited 50 years later. Many people like to think that any child, with the proper nurturance, can blossom into some kind of academic oak tree, tall and proud. It's just not so.
Multiple intelligences provides a kind of cover to preserve that fable. "OK, little Jimmie may not be a rocket scientist, but he can dance real well. Shouldn't that count equally in school and life?" No. The great dancers of the Pleistocene foxtrotted their way into the stomach of a saber-tooth tiger.
That is the root of the matter. Too many people have chosen to believe in what they wish to be true rather than in what is true. In the main, the motive is a pure one: to see every child as having equal potential, or at the very least some potential. Intelligence is a fundamentally meritocratic construct. There are winners and there are losers. A relative doofus may live a comfortable life so long as his or her parents are wealthy. However, clawing one's own way out of abject poverty is best achieved with a healthy dose of both motivation and "g."
Naturally, we must be careful to avoid the fallacy that some people deserve to live in poverty, or that entire groups of people are inherently inferior in regard to intelligence. In the past, those arguments have been used to support oppression, racism, and slavery, and we must not repeat those mistakes.
Yet the belief that intelligence does not exist as a single, reliable, important, genetically determined construct is an equal fallacy. Unfortunately, some children and adults are just unintelligent. It's not fair, it's not politically correct, but reality is under no obligation to be either of those.
A pedagogy designed to identify strong and weak areas of achievement is not a bad idea. But believing that such an approach rests on the existence of multiple intelligences has real risks. It could lead us down the path to intellectual relativism. Students encouraged to explore their talents in dance or socializing may find themselves slammed against a wall of reality when expected to actually know how to do algebra or read a book in college. I'm not opposed to exploring those talents (that's what recess and gym classes are for, and getting rid of them has been a horrible idea), but national and international tests indicate that we may be doing so to such an extent that we are overwhelming our curricula.
Gardner's theory of multiple intelligences was a great idea and worth investigating. It's just not panning out. Hanging on to the theory for nostalgic or political value is not science. It's time that we begin to work with the reality that we have, not the one we wish we had. To do otherwise would be just plain stupid.

Christopher J. Ferguson has been promoted to associate professor in the department of behavioral and applied sciences, and criminal justice at Texas A&M International University.