I usually think of it in terms of riding momentum; I'm sure a lot of people can recall instances where I'd get dug so far into a debate that I was started holding my position mainly for the sake of doing so more than anything else, but I'm hardly the only example. Since I know I'm prone to it, I try to watch for it, and try to reevaluate my largest and most deeply held beliefs from time to time to see if I'm really motivated by logic, morality or just habit. It cuts both ways, too; for every person who'll take a position to gain the favor of those holding it, then gradually adopt it as their own in sincerity, there's another person who'll be contrary for the sake of being memorable or provocative (in fact that's pretty much the definition of a troll. )

But let's be honest with ourselves here: When do we ever do anything in the absence of outside pressure? It may not be obvious, but it's always there to some degree. That doesn't negate or deny free will nor accountability, but there are always influences on any decision we make; that's a large part of HOW we make decisions in the first place. And, yes, I think most people want to be consistent in most respects, not predictable, maybe, but not erratic either. That's OK as long as we don't overcommit to positions; when we take a position on little or no data we can't be afraid to reverse it when we have all the facts. Typically I become more intractable the longer and more deeply I hold a given view, and I think most do, but that's probably more than anything because if we care enough about it to give that much time and attention, and our position remains the same, we'll have a large mass of data reinforcing it. There are very few issues on which my mind CANNOT be changed, but there are many issues that would take a mountain of data to tilt the scales the other way because there's already so much on the other side.