IQ, schooling and policy

Bryan Caplan of Econlog seems to argue that:

1. Schooling has an effect on earnings and economic growth. This may justify government spending in education.
2. IQ has an effect on earnings and economic growth. There is no rationale for government intervention here because we can not change IQ.
3. Discarding IQ's role in earnings and economic growth, as some "left-wing ideologues" do, overstates the rationale for government intervention.

Here is an excerpt:

Does it matter that IQ matters? Of course! An investment in education that looks extremely profitable if you don't control for IQ could easily be a big waste of money. The reason: If you don't control for IQ, you are giving education a lot more credit than it deserves. To say "Let's focus on the things we can change" dodges the hard truth: After you adjust for what you can't change, the things that you can change may give you very little bang for your buck.

Thus, IQ is highly policy-relevant after all. The left-wing ideologues who damn anyone who even thinks the letters "IQ" are actually on to something: IQ research does turn out to be a rationale for "right-wing" laissez-faire policies. The more IQ matters, the more likely it becomes that existing government policies are a waste of money - and that you would get a bigger payoff by doing less - or maybe nothing at all.

I can see no difference between IQ and schooling as matters of policy.

1. We can change schooling. We can implement a successful policy of increasing schooling and, by doing so, achieve some economic benefits.
2. We can change IQ. We can implement a successful policy of increasing people's IQ and, by doing so, achieve some economic benefits.

But, someone can reply, IQ is heritable!

1. Yes, IQ may be heritable.
2. But years of schooling (or any other measure of schooling) may also be heritable.

And,

1. We can change the mean and the variance of heritable traits.
2. We can even change the heritability of traits.

So, we can implement policies to increase or decrease average schooling and IQ, their variance and their heritability (the proportion of variance statistically associated to genetic relatedness).

And I think governments should not intervene in schooling or IQ.