There is a new view — or should I say an old view? — percolating in the blogosphere: "There is something special about IQ. We must conserve IQ at very high cost, and gains in IQ will bring very high social returns."

In practical terms, "Conservation of IQ" is used to argue for limits on immigration, against various meliorist attempts, and possibly even for eugenics. I’ve heard it used to argue for outlawing marijuana, which of course destroys brain cells.

Imagine an evolutionary approach: given the Industrial Revolution and subsequent developments, perhaps IQ has higher social returns than was once the case. So we must rebuild our intuitions to favor IQ more than otherwise. When evaluating policy, one question is simply to ask whether it raises or lowers average IQ within a polity or region.

There is also a methodological argument: IQ is (arguably) prior to economic notions of rationality. Perhaps economists should treat rationality as an open variable and dependent on IQ.

I don’t assign special status to The Conservation of IQ for two reasons. The first is the Flynn effect, or the fact that measured IQs have been rising steadily over time. This implies some combination of a) IQ gains come naturally under conditions of progress, and b) IQ statistics are to some extent phony and don’t measure real intelligence. We can debate the mix, but either deflates fears that IQ is somehow especially scarce or endangered. These data also suggest that IQ is an artifice to be unpacked rather than a primary category.

Second, defenders of the IQ view tend to read evolutionary biology and intelligence research. My roots are in cultural history. Clusters of amazing achievement come and go pretty quickly, usually through some mix of environmental effects and luck. Look at Venetian painting. It was much better centuries ago, but I doubt if Venetian IQs have been falling. Once we see how such enormous differences can be explained by non-IQ factors, I again don’t obsess over the variable.

I do think economists should study IQ more. And for sure I value it in friends. But when analyzing social problems, institutions, social psychology, and economic mechanisms still command most of my analytic attention.

A few of you had asked about IQ, I crammed my thoughts into this one post, so this is #04-07 in a series of 50. Do, by the way, save your thoughts on immigration for other posts.