It took me a while to figure out what Harry Brighouse was getting at in his latest post on Crooked Timber. He was explaining why there isn't much need for introductory political philosophy textbooks defending conservative positions, and he said there was no need. One of the comments on his post misunderstands him to be saying that "conservatism is suspicious of the applicability to politics of complex abstract argument", which I think is laughable and not at all what Harry meant. (I should say that there are conservatives who are guilty of this, but there are just as many liberals who are. Just look at Al Franken, who has no basis for anything he says.)
Harry's point is that conservatives don't need to come up with a systematic defense of their views, since the other views bear the burden of proof. Why do non-conservative views bear the burden of proof? He doesn't say, but he acts as if it's true by definition. The idea seems to be that conservatism involves remaining where we are and continuing policies that have a long-standing tradition.
I don't know what I think of this. On one level I like the idea that conservatives are the default, and everyone else has to bear the burden of proof (because I tend to be more conservative). However, it seems to me that ideas I consider liberal have become default (either legally or among philosophers). Personhood is hardly ever thought to be an essential property and is rather a vague property that something gradually becomes. Hardly anyone even tolerates the position that homosexual sex (or premarital sex, for that matter) even might be wrong. Environmental views on what I think are still at least somewhat open issues are assumed to be settled in favor of liberal positions. It's almost academic heresy to say certain things about African-Americans' test scores and affirmative action, things most conservatives think are just plain empirically observable facts. It's amazing the derision I've heard about trickle-down economics among philosophers (though I suppose it is the orthodox view among economists).
So I don't know how to determine what the default view is. That's why I think all the arguments should at least get some time on any given issue, even if some of them are for views most people just assume, though that doesn't necessarily mean equal time, especially when arguments for less commonly held or understood views require more time (as John McWhorter's position on affirmative action takes far more time than the position in The Bell Curve or the standard conservative line from Antonin Scalia). It does mean that most people who teach these courses aren't teaching everything they should.