I’ve been re-reading a couple of books by neurologist Oliver Sacks — The Man Who Mistook His Wife for a Hat and An Anthropologist on Mars. What I get out of Sacks is an appreciation of the stunning complexity (and fragility) of the human brain.

Our brains are constantly doing tons of extremely sophisticated data processing, all without our having the slightest awareness of it. Things that seem perfectly transparent to us — looking at a coin and seeing that it’s round, for instance — are not to be taken for granted. The perception of the roundness of the coin is (unless something goes terribly wrong) constructed in the brain. If the brain module that understands shapes develops a lesion, we literally can’t tell what shape the coin is.

Last week I was talking with a very bright young man at a party. Somehow the conversation veered from philosophy to evolution. The young man found it difficult to believe that language is the product of a genetically inherited instinct.

I mentioned an example from Steven Pinker’s wonderful book The Language Instinct, the fact that children whose parents speak a pidgin (“me speak pidgin” would be an example) will spontaneously transform it into a creole — a language that has grammar. An orderly grammar is generated spontaneously by the children’s maturing brains, because young human brains are hard-wired to find and understand grammar.

My young friend felt that grammar could arise simply as a result of general-purpose intelligence. (I didn’t ask him to define that term.) But as Sacks illustrates over and over, coming at the question from various angles, what we consider intelligence is the result of dozens or hundreds of processes that are occurring in the brain from moment to moment. Usually we can rely on these processes. Except when we can’t.

Without the brain’s effortless automatic processing, you wouldn’t even know what the color red looked like. Occasionally, people get hit in the head and lose the ability to perceive color. Their eyes still work, but their brain switches to black-and-white.

Your ancestors and mine lived in a world in which the ability to see red was useful. For one thing, you can find ripe fruit more easily! So individuals who could see red tended, over the long haul, to have more surviving offspring than those who couldn’t. The genes that produced not only the eye’s ability to see red but the brain’s ability to notice the colors that the eyes were seeing had an advantage over genes that didn’t. So most of us have those genes. If all goes well in the developing foetus, the genes are expressed, and we can see red.

If you can’t see red without the intact functioning of a specific kind of wiring in your brain, why should you expect that you’ll be able to figure out how to tack tense markers onto a verb, or even understand the difference between a verb and a noun, without a specific kind of wiring?

I’m not convinced that any sort of general intelligence exists apart from all of these intricate intra-cranial subsystems. I would speculate that what we would call general-purpose intelligence emerges when all of the subsystems are functioning optimally. Sacks writes, inter alia, about people who have profound levels of musical talent and yet can’t tie their shoes. Can we say they’re intelligent? Not in any general sense, no. They’re intelligent with respect to music, because the musical functions of their brains are intact.

The ego (“Hey, I’m really smart!”) is a thin, thin film floating atop this seething mass of unconscious activity. In a very real sense, we don’t know what we are.


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