Is the undeniable dominance of the left on today's college campuses a result of discrimination against political conservatives in academia? This question has been raised in response to Prof. Robert Brandon, chair of the philosophy department at Duke, and at least one other professor there, who apparently believe that the phenomenon has a different explanation: Conservatives are stupid.

Eugene Volokh, among others, had a good time making fun of this charge. But Andrew Sullivan chose to respond with an implicit countercharge, in the form of a long, familiar of series of anecdotes from the trenches, demonstrating what might be described as a "hostile environment" towards conservatives on campus. His argument was presumably that bright conservatives have been hounded off campus, rather than failing to make it there on their own merits. Crooked Timber's Kieran Healy offered the obvious rejoinder: that conservatives who generally don't accept anecdotal evidence and numerical disparities as proof of racial discrimination shouldn't be so quick to accept these signs as proof of ideological discrimination.

Both sides, however, have tacitly accepted a highly questionable premise: that there are intellectually coherent philosophies that can be described as "left" and "right", and that adherents of the former can therefore be said to be have dominated academia for some appreciable length of time. In fact, much of what would be described as leftist today--racial and sexual separatism, isolationist anti-militarism, protectionism, suspicion of presidential malfeasance and abuse of power, hostility to Israel, environmentalism, even opposition to tax cuts--would at some point in the last fifty years have been described as a right-wing position. A similar list, of course, could be compiled of "conservative" views that were, not so long ago, viewed as incorrigibly liberal.

This legacy of flip-flops supports my long-standing contention that terms such as "left", "right", "liberal" and "conservative" represent coalitions of groups sharing common interests, rather than consistent collections of ideas. The persistent collective allegiance of a particular group, such as academics, to such a coalition is much less mysterious than its adherence to a specific ideology. After all, a group with a particular stable socioeconomic position is more likely to maintain common interests with a more-or-less fixed constellation of allied groups, over time, than it is to maintain a common set of political beliefs.

And it is hardly surprising that academics, as members of the educated, professional white-collar middle class, have over the years allied themselves with other members of that class, even as their actual positions on all sorts of issues have changed radically. (Members of, say, the modestly educated, blue-collar working class, or the property-owning investor class, show a similar consistency of affiliation and volatility of concrete political position.) No accusations of stupidity or discrimination are necessary--the simplest explanation is that professors are liberal because liberalism is defined, to a large extent, by the views and preferences of professors and people somewhat like them.