James Lileks has some thoughts on the social side of politics, i. e. why do some people think that people in the other party are subhuman:

I wasn�t completely comfy on that side [liberal]; I�m not completely comfy over here. So it goes. But I don�t ascribe an moral inferiority to friends and neighbors who have a different path to common objectives - unless they insist on proving they're willfully stupid, and live in an ideological exoskeleton that dictates which way they must move regardless of new data.

An old friend who still believes what we believed in college took me to task the last time we met, and wondered where Mr. Middle Ground had gone, why I no longer seemed interested in finding commonality. The simple answer is that there is no common ground with people who think you�re a political leper, a winged monkey in the service of a green-skinned Nancy Reagan in a witch�s hat. Respect works both ways, and if it�s not returned, then something changes. There�s a difference between thinking someone�s strategies are wrong, and thinking them a knave who acts from ignorance at best, and more likely acts from malice. If that�s what you think, I am not interested in changing your mind. I am not interested in working together. I am not interested in suffering your insults or your condescension or any other form your preconceptions take. I am interested in defeating you, and getting down to work with the people who come in your place, and grant me the respect I�ll give them.

This is why crowing among Republicans is so distasteful and all the weeping and gnashing among Democrats is so silly. When I talk about Democrats disparagingly, I'm talking about their leaders and platform, not all individuals who vote Democrat. I registered as an independent some years ago, despite being raised Republican, because I'd seen too many Republican candidates who made me feel ashamed to be in the same party with them. I tested the waters as a Democrat, but I had the same problem. The national spokesmen for the Dems didn't speak for me, and I didn't want to be identified with them.