My Sunday question this week was about why liberals don't use Democratic House and Senate primaries the way that conservatives use Republican primaries.
Nick Baumann believes it's just about an ideology gap, and refers to Gallup's charts which show that far more Republicans identify as conservatives than Democrats identify as liberals.
I'm pretty skeptical about this. It's certainly true that there's a big difference in self-identification, but it's not at all clear what that means. It does not, for example, mean that the movement conservative position on most issues tends to be the most popular one. Instead, polling majorities on policy are all over the place.
I don't want to say that the self-identification thing is totally meaningless. It certainly seems to reflect something out there, and it has consequences; in terms of primary elections, it's certainly true that Republican candidates fight over who is "really" conservative while Democratic candidates don't really do that. But does that have anything to do with issue content? Does it have anything to do with what we think of as ideology? I don't think there's a lot of evidence for that.
Again: the difference that I was talking about in Congressional primaries doesn't seem to be there at the presidential level. For presidential nominations, both sides seem to me to have a more or less equivalent set of litmus test issues, and you really can't get nominated unless you're on the correct side of them -- and I think it's hard to make the case that Democrats are more flexible about it than Republicans, or more likely to nominate party moderates.
And as for the self-identification numbers, I just don't think they're worth very much. Something, yes, but not very much.