I have to warn you -- this might be a bit rambling. And it's not exactly definitive, either (especially towards the bottom of this very long post; among other things, I'm not as up on some relevant literatures are I should be). Take this, perhaps, as a different way of thinking about some ideas, ideology, and other such things, rather than something I'm going to assert is the correct way of looking at those things. That said...
There's been a bunch of interesting comments recently around the blogs concerning the general topic of ideology. Matt Yglesias did an item in which he noted that he's for deregulation of various things, but that it doesn't make him feel as if he's a conservative on those issues. For a two paragraph post, he really started something, with Conor Friedersdorf using it to take a(nother, and completely justified) swipe at Mark Levin (with a follow-up), and then Adam Serwer got in on it, first making the Chait-esque point (but see Kevin Drum) that American liberals don't believe in big government the way that American movement conservatives believe in small government, and then making what I think is the better point that American movement conservatives don't really believe in small government in that way, either -- they believe in small government rhetoric, but in reality are happy to support government intervention in support of other important goals. Yglesias also posted recently about what he sees as a possible decrease in ideological politics around the world (except, in his view, the US).
There's a lot in here. For one thing, Yglesias says that his "impression is that politics wasn’t especially “ideologically” before the late 18-th century," and also talks about (in the post linked first above) how "The “left-wing” position is to be against this stuff—to be on the side of the people and against the forces of privilege." But those things are connected, and in my view, mostly irrelevant to 21st century politics, or at least 21st century American politics. "Left" and "right" (as Yglesias I'm sure knows) come from a specific place and time: from the French Revolution. Indeed, to vastly oversimplify something on which I'm not an expert anyway, it's not wrong to say that "left" and "right" began as simply attitudes towards the French Revolution, for or against. This did, indeed, put the "left" on the side of the people -- against the Crown, against nobility, and at least in France, against the Church. This translated reasonably well to the rest of Europe during the 19th century, when politics was really involved in whether "the people" would or would not rule.
However, and this gets back a bit to what I was talking about recently, once you have a democratic republic, it's not clear that "left" and "right" mean anything -- because as the constitution-makers of revolutionary and post-revolutionary Americans discovered after 1776 and through the 1780s, in a democratic republic there's only people. One of the problems they had to deal with was that Montesquieu said that you're supposed to have different branches of government representing different estates within the nation -- but in America, there was only one estate, so what powers were there to balance? Of course, Madison's brilliant solution (as he describes in Federalist 51) is to balance the people against each other, thus creating more, not less, power.
OK, but...we do in the US have people who call themselves liberals and conservatives, and we have "left" and "right" in other democracies even though it's not about support for or opposition to the French Revolution, so what is it about? The answer is not at all easy, at least in my view. One way to talk about ideology, the way that public opinion researchers tend to think about it, is just about knowing which issues are supposed to go together -- so that if you support, oh, gun control and abortion rights, you might know you're also supposed to support more government spending on education and oppose the war in Iraq. By that measure, Americans tend not to be ideological in general, although people who know a lot and care a lot about politics, people like Yglesias and Friedersdorf and Serwer and me and you (since you're not reading on into such a long post on this blog unless you're way high on the scale of political awareness), do tend to be far more ideological by that measure. Then there's what Friedersdorf refers to a couple of times in his discussion, first principles. It could be the case that there are deep principles at stake between American liberals and movement conservatives, and that positions on specific issues of public policy flow logically from those principles. Friedersdorf seems to think that's the case, and I'd guess that most people do. I don't, for the most part. Unfortunately, while it is I think an empirical question, it's also (in my view) an impossible one to get at. At any rate, that might be going on.
Let me propose a third way to look at it, either in addition to or instead of either just grouping issue positions together because you know they sort that way in our politics, or issue positions deriving from first principles: groups, and impulses.
Groups: we belong to groups, and in those groups we form alliances with other groups, often through political parties -- which are, in addition, one of the types of groups to which we might join. These groups, as groups, hold positions on issues of public policy, sometimes out of self-interest, sometimes out of custom or habit. We tend to adopt the positions of the groups with which we identify, or with which our groups are allied, or which leaders of those groups profess publicly. Then we go back and find justifications for why that basket of issue positions go together. That's not a bad thing -- even those of us who think self-interest in politics is perfectly fine also believe that it's both natural and healthy for political actors to (at least sometimes) express their self-interest in the context of principles that everyone else can recognize as public spirited.
So to some extent, looked at this way, ideologies are the residue of the connections we make between policies we already support, although then its also true that those connections might also influence us and others as we make other choices about who to ally ourselves with, and what new positions to adopt.
But I think that's only part of it; I do think that there's something authentically different between liberals and conservatives, at least some of the time, and at least in some cases. If not first principles, though, perhaps we can call them impulses. To me, the liberal impulse is basically: We Can Do Better. And the conservative impulse? Don't Make It Worse. Liberals, or perhaps all of us when we're inspired by the liberal impulse, look around and see a variety of problems and available resources and want to alleviate pain and suffering; they want to solve problems. Conservatives, or perhaps all us us when we're inspired by the conservative impulse, remember all the cases of noble intentions gone awry, the cases of unintended consequences, the cases in which problems seemed terribly severe but then they seemingly melted away without anyone, and certainly not everyone collectively, trying to address them. Liberals appreciate the promise of the future; conservatives appreciate how rickety the accomplishments of the present are, and how easily what we think is safe can be destroyed.
I don't know; reading back, that seems a bit on the trite side to me. My real point is that to dress these things up as ideologies, and in that in most cases "first principles" have little to do with our approach to public policy preferences, even among the most politically sophisticated who are most likely to conform to our political parties' platforms and to therefore poll as ideological, is to miss something important. So I'm not saying that either the "sorting issues" or the "first principles" way of looking at ideology is wrong; I'm just saying that the groups-plus-impulses approach may (also) help us understand what's going on.