Income and intelligence

Due to a lack of reasonable postings, I stopped reading Greg Mankiw's blog a while ago. Specifically, there were at least 5 (there could have been more) posts in a row where his blind ideology got in the way of a reasonable interpretation of the facts.

It looks like he's done it again, though this time I only know about it because there has been such an uproar over his comments on intelligence and income. It looks like he thinks the rich are just naturally smarter.

Some interesting discussions of the data though have come out of it. Brad DeLong argues there is in fact a big piece of the correlation lacking, and Paul Krugman argues that it may just be the income that's doing all of the work.

Then, to make the details more interesting, Alex Tabarrok at MR looks at adopted kids and finds no effect of income, but as the comments make clear, there are plenty of problems with looking at adoptees.

I really don't know the answer myself, though I am more and more convinced that it is unanswerable. Let the nature versus nurture debate continue ...