[Cyber Wolf]

Part of it is that's how humans are. You find that anywhere there's two ends of a situation to be on.

And that leads to another, probably bigger, part: the fact that there's a perpetuated selection of two choices: conservative/liberal. Whenever you take a situation and give aspects of it labels with specific definitions, you'll have people splitting into camps. Us vs Them. Hatfield vs McCoy. East Coast vs West Coast. And part of being in one camp or another is that you're not LIKE the other people. And to prove it (to yourself or to your campmates or to the world), you have to not be like the other campers. The more you show you aren't like them and the more you show you don't like what they do, the more you prove you match whatever camp you've aligned yourself with. Besides, if you're trying to do X, Y and Z and the other camp keeps doing things that disrupts or overturns your efforts, you're bound to get a little pissed off after a while. Never liked political labels meself.

The final part is that so many issues that people tend to deeply divide themselves about have a tendency to get personal on some level. How personal it gets depends on the individual and the issue. Abortion, for example. One lady from camp X firmly believes the fetus is a living human from conception and another lady from camp Y believes that since its feeding off the woman's nutrient supply she should at least have the choice to have it removed. Camp X lady wants to save a life, Camp Y lady wants to save her choice. To Camp X lady, Camp Y lady wants the choice to commit murder legally. Flip it around, Camp X lady appears to want to relinquish all American womens' control over their own body, without their consent. And from that point, you get them calling each other murderer, fascist and other lovely things...