Intelligence is like creativity in that everyone wants it but no one seems able to say what it is. Its high status is confirmed by theories of questionable academic merit that nevertheless achieve popularity and influence, largely, it seems, because "intelligence" is in their titles. Even Howard Gardner, propounder of the fashionable theory of multiple intelligences, concedes that his theory would not have attracted such a devoted following if it had been couched in terms of varying abilities - which amounts to the same thing.
The difficulty of defining "intelligence" reminds one of St Augustine's famous remark about time, whose gist is that we know what it is when nobody asks, but when asked, we are baffled.
Definitions of "intelligence" tend to be both fallacious and tendentious. Most commonly they implicitly twist the concept so that it can be empirically tested. Gardner, for instance, defines intelligence in terms of the ability to solve problems and fashion products. This fits the empirical model: problem-solving can be tested and products straightforwardly assessed. But intelligence can also, more strikingly, be seen in the creation of problems, by putting an iconoclastic cat among uncritically confident problem-solving pigeons. Indeed, intelligence that disrupts previously assumed paradigms may be of greater value than solving problems within the accepted norms. Moreover, numerous cases of intelligence cannot intelligibly be regarded as involving the fashioning of products. Ideas cannot legitimately be regarded as products.
Disciples, unwilling to consider criticism, typically attempt to defend definitions by the common if unwitting ruse of extending the meaning. In this case, they claim that "product" should be construed more widely than its dictionary definition of things or substances produced by nature or manufacture. But this would not only flout its normal meaning, but to cover all possible instances of intelligence, the meaning of "product" would have to become vacuously wide, for almost anything one does would have to count as a product.
Speed of response is the most commonly assumed defining characteristic of intelligence. This also conveniently fits the empirical paradigm: speed can be quantified. Yet the fact that one person reaches conclusions more slowly than another does not in the least necessarily imply lower intelligence. On the contrary, it may reveal a more careful consideration of the issues.
Speed of response is, of course, a central criterion of intelligence quotient. Mensa, the high-IQ Society, is ipso facto supposed to be a society for the highly intelligent. A Mensa advertisement presented a puzzle involving the manipulation of symbols and was headed: "Can you solve this puzzle faster than Einstein?" This is exquisitely ironic, since Einstein, whose life is a fund for disturbing educational shibboleths, attributed his later success largely to his being so slow at school.
This whole issue is by no means a mere verbal quibble, for to conceive of intelligence in such terms as I have criticised would be implicitly to ignore or fail to encourage other, potentially more important, kinds. Certainly intelligence may be manifested in speed of response, solving problems and creating products, but fresh vision, new ideas and approaches may be even more valuable expressions of intelligence, and they may not fall into any of these categories.
It may be possible to formulate criteria of intelligence in some particular contexts. No doubt an experienced shepherd could provide clear criteria for what counts as an intelligent sheepdog. But in general, I submit that intelligence is indeterminable, and thus attempts to provide defining characteristics are misguided.
Professor of philosophy
University of Wales