The empirical evidence that academia is far to the left of everyman views (at least in the US) are pretty clear. The debate tends to center around why – some on the left, for example, might argue that conservatives are just less intelligent (and thus would not cut it in academia – anecdotally, by the way, some of my conservative friends will argue that academia is a terrible occupation, and “smart people” will prefer to go into the private sector where they can both think for a living and get paid and not have to deal with tenure considerations), or that smart conservatives come to academia and learn the “truth,” becoming more liberal. But of course, there’s an intermediate hypothesis between “conservatives don’t try to enter the funnel of academia” or “conservatives who enter the funnel of academia become liberal” – perhaps conservatives try to enter the funnel, but are rejected, and the only ones who make it through either have weak enough convictions such that they are considered palatable (and therefore do become more liberal once they are surrounded by those with strong convictions) or enter in fields where ideological leanings matter less (e.g., science or math).

This article is not an empirical study, so it should not convince you that this third hypothesis is the state of the world – it is merely a set of anecdotes that show you how it could be the state of the world.