When I was more to the left ideologically, I found over time that I didn't like what struck me as a need to be in a state of more or less constant anger about the world; ever on the lookout for enemies and sellouts. That just isn't me, psychologically or emotionally. I decided I was ill-suited to the left in emotional terms, so I became a more mainstream liberal. Very comfortable with it.I couldn't do it either, which is why I moved more into the mainstream as well a few years ago. Plus, there's the Christianity thing. I'm not talking about social issues, so much as the idea that the world just cannot be perfected--we can change things, improve things, but fundamentally, we'll never change the human condition. We'll never completely eliminate greed, the will-to-power, ignorance and the rest from humanity. We can restrain them, though. We can make progress, we can exceed even our wildest expectations over time. But we'll never triumph over all the bad things I mentioned, because humans can't really triumph over human nature. And we have to realize that progress is always a lot more tenuous than we think. Case in point: torture.
The thing is that the most vociferous advocates on both sides of the spectrum don't seem to share this view. I respect that kind of idealism, even if I don't agree with it, even if it pisses me off when it's willfully obtuse, as much of the netroots "rebellion" over health care has been. But if you think it's possible to create a perfectly just society, then every injustice can't help but be an infuriating reminder of how far away we are from where we need to be. If you don't think it's possible to create a perfectly just society (emphasis on perfectly), then you see injustices and try to fix them. There's an idealism to group #1 that can often lead to frustration, which reminds me about the scores of communists who got disillusioned when their perfect society didn't materialize and subsequently became right-wing, like Irv Kristol and Whittaker Chambers.