People, and what they consider important, are not static. They are dynamic, in a constant state of flux. That isn't to say that people don't gravitate towards certain beliefs most of the time, we do. However, the priority of each indicator used to identify someone as a lefty or centrist (or right-wing fuckhead) varies from individual to individual based on their personal experience, which is temporal and constantly changing.

For example, a person may believe that killing another person is generally wrong, that there should be no death penalty and that we should have gun control to the point where almost no one has them - a generic leftist position. Later in their life, their spouse is murdered by a remorseless thug with a long rap sheet. At this point, they feel the death penalty is justified, not only for revenge, but for the safety of all of the thug's potential future victims. Also, because of the anxiety created by the event, the person not only reverses their position on gun control, but they go out and purchase a handgun. Now, that person appears to be a rightist, based on those positions. But what if they also believe in universal health care, ending corporate welfare and increasing regulation and a comprehensive plan to nationalize illegal immigrants? Are they now a centrist? And how does what the person perceives themself to be factor in?

The problem is with the terminology and how these terms are defined. If "left" is strictly defined by a set of positions and "right" is strictly defined by another opposing set, then everyone else is "centrist," which would literally be almost everyone, since very few people rigidly fit any one category for any length of time. But, if we're mostly centrists, then why isn't there a centrist party? Are we being forcibly polarized into a false political binary? Or is it that we simply need a better definition of centrism than "not strictly left or right?"