Kind of riffing from my earlier entry on hypocrisy, here's an attempt to boil down an underlying rift between left and right. It's all about actions and ideals.
The right believes that a strong and powerful set of ideals must be protected at all costs, even if it occasionally means that their actions don't align with their ideals.
The left believes that they must reconcile their actions and ideals at all costs, even if it occasionally means that they have to relax their ideals to do so.
Obviously, neither is an absolute truth, but they're two archetypes that are interesting to think about.