The whole thing seems to hinge on the arbitrariness of professors' intellectual leanings. How do we know they are so arbitrary? If you polled all the economics professors of major universities in the US, would their outlook confirm MM's argument? Or is his data obsolete, based on a stereotype?

I don't model academia as having a single bias. In my experience, it is a bunch of subcultures -- for instance, economics professors tend to love libertarianism, and sociology professors tend to hate it. I have been "informed" from time to time that my university education was nothing but left-wing propaganda, although I don't recall much mention of politics on my physics course.

Another thing that is peculiar about this argument is the relative lack of emphasis on the influence of familt, church, etc on people's thinking. If the tertiary education sector is so influential on the US, why aren't most US citizens believers in evolution?