What Is Intelligence?

Over at the Unz Review, an innocent named Sam complains that in writing about IQ, resident psychologist, James Thomson:

… does not address that/those portion(s) of the human brain that deal with intelligence.

But like the psychologists, Sam has the wrong model. The brain isn’t like a computer. There is no central processing unit that determines computing power, FLOPS or IQ.

The brain is the product of evolution. It is built on the Rube Goldberg principle. A bunch of junk put together and then endlessly tested in the struggle for existence, endlessly modified by mutation, and endlessly retested.

The end product of this evolutionary process does all kinds of amazing things in amazing ways, but not in the neat tidy ways a good engineer would design things to work, but maybe completely crazy ways, but ways that work nevertheless — somehow, just…

The result is that intelligence is not one thing. It is not the product of one bit of brain or one brain module. It is the product of numerous neurological modules and networks, each doing its own thing, each dependent on its own particular structure and biochemistry, each subject in its development to its own set of controlling genes. Did you know that, in the male brain, there’s even a specialized knot of neurons that seems to have no function except to light up at a girl’s smile? Cool.

That’s why IQ testing is nonsense. It’s possible to be both a genius and an idiot — in different areas of mental activity: an obvious fact, but one that seems rarely to have crossed the mind of a psychologist.

But the IQ-ist's notion of intelligence is much wronger than would result merely from the mistaken notion that intelligence is a single thing embodied in a single bit of the brain, equally involved in the composition of a symphony, the formulation of a mathematical theorem, or the deftness of the artist's or surgeon's hand, and hence to be viewed as a single variable defined by one number, or intelligence quotient.

The IQ-ist compounds the error of assuming that the brain has a central processing unit that determines the intelligence of every thought or action, by making the further error of assuming that intelligence is strongly genetically determined. This idea leads IQ-ists naturally to a toxic belief in the existence of immutable racial and class hierarchies in intelligence, an idea bolstered by test results that blatantly confuse cultural and environmental differences in cognitive development with racial and class differences in genetic endowment for intelligence.

It is true that intelligence has a genetic basis, as does every other organismal trait. But the influence of genetics is always modified by environment. Raise a child in an iron cage without human contact, as was the fate of the Russian Tsar, Ivan VI (1740-1764), crowned at the age of two months but deposed a year later and then held in solitary confinement until his murder 23 years later, and it will severely stunt the mind, as was the case with poor Ivan. From that we can deduce that  intelligence is not fixed, but is something that grows or withers in response to experience and use.

That, in turn, means that intelligence is not fixed genetically or socially. It develops over time, increasing or decreasing according to circumstances. Hence, the idle Harvard undergraduate with a perfect SAT score may be outpaced intellectually by the committed student of lesser SAT-endorsed intelligence who strives for mastery whether in academia, socially or in some other sphere of endeavor.  

Accompanying growth or atrophy of intellectual skills occur radical changes in brain structure. During infancy,  hundreds of thousands of the brain's synaptic connections are eliminated every second over a period of many months. Later, during adolescence, much of the tissue of the cerebral cortex, the supposed seat of intelligence, is eliminated. Such developmental processes undermine the idea, common among IQ-ists, that intelligence is a function of brain mass. The implication, rather, is that, depending on mental effort and experience, intelligence grows or fails to grow whatever the individuals genetic endowment. 

And that is obvious when you come to think of it. Give a plumber a plumbing problem and he'll likely figure it out faster than you could, even if you've got a high IQ and understand hydraulics. Same in any field: hard work and experience increases performance, including problem-solving skill, and that equals increased intelligence.