g

Andrew Sullivan links to this piece by James R. Flynn, discover of the eponymous effect.
Shattering Intelligence: Implications for Education and Interventions

Flynn starts by noting quite sensibly that IQ is a powerful predictive tool:

The concept of a general intelligence or g factor has proved enormously fruitful in two respects. On the level of individual differences, it captures the fact that if one person outperforms another on one kind of conceptually demanding task, that advantage is likely to persist over a whole range of other cognitive tasks. On the level of group differences, we find that the average Full Scale IQ of two groups on a good IQ test often predicts things like their occupational profiles. Various occupations have minimum IQ thresholds. If 50 percent of group A scores above say an IQ of 100, while only 16 percent of Group B do, then Group A will have a three to one ratio in its favor in terms of the proportion of its members who are professionals or technicians or managers.

Any analysis that ignores this, or pretends that IQ has no predictive power, is too contrary to the facts to thrive.

Flynn goes on to note that:

Despite all the triumphs of the concept of general intelligence, I believe intelligence is like the atom: you have to know both why its parts cohere and why they sometimes fly apart. Americans made massive IQ gains on the WISC between 1947 and 2002 amounting to almost 18 points of Full Scale IQ. These gains ranged from only 2 points on the WISC subtest called Information to 24 points on the subtest called Similarites (what do dogs and rabbits have in common?), despite the fact that both have the cognitive complexity that makes them good measures of g.

His argument is the sensible and well grounded idea that intellectual faculties have great plasticity. Your brain gets good at things you work hard at doing.

There is a lot of good stuff in this essay, and the whole thing is worth a read. Let me conclude with one of his morals:

Cognitive exercise
The first implication of the new perspective is the benefit of persisting in cognitive exercise throughout life. There is the dramatic case of Richard Wetherill. He played chess in retirement and could think eight moves ahead. In 2001, he was alarmed because he could only think four moves ahead but he continued an active mental life until his death in 2003. Autopsy showed that his brain was riddled with the plaques and tangles that are characteristic of Alzheimer’s. Most people would have been reduced to a state of total confusion. This does not mean that cognitive abilities fail to decline with age. After all, at any given age, an athlete is better off for training. But however hard you train, your times will get slower as you age.

The brain is much more like our muscles than we had thought, even in the sense that specialized exercise affects different parts of the brain. Autopsies show that the brains of London taxi-drivers are peculiar. They have an enlarged hippocampus, which is the brain area used for navigating three-dimensional space. Here we see spatial abilities being developed without comparable development of other cognitive skills. To develop a wide variety of cognitive skills you need a wide variety of cognitive exercises.

Which reminds me, I need to get back to Conceptual Mathematics. The math is very simple, but my brain has trouble getting around some of the ideas and definitions. A lot of familiar terms (e.g., injective, surjective, isomorphism) occur with new meanings - meanings that to me often seem quite unrelated - but they aren't.