He was a professor of economics and author, involved to an extent in politics (at least by giving commentary), and is by all accounts a very shrewd intellectual.

And black. And not very convinced by a lot of the "this is racism" arguments that are favored on the left (including favored by left-leaning black individuals).

He might be wrong in some of his views, but it seems very hard to argue that he is wrong because his mental development has been impaired.