I just got to wondering this lately when I see so many people digging in so hard on political views (or even programming language stuff.)
But ... I try not to make a decision before I've had a chance to evaluate the question. Sometimes I find myself having to act prior to having a decent understanding, but I don't count that, because that's a conscious decision.
I also find that I have a lot of fairly nuanced positions on things. To pick some HN-relevant examples, I've been writing C++ since the late 80s. To this day, I cannot clearly state that I like it or don't; similarly, I started using Java with version 1.0 and again, I don't have a simple "Java is good/bad" opinion.
Similarly with politics: while I can usually manage to find an "on balance" position in favor of one person or party, there's never been a case where I felt an individual was 100% good or bad.
I think the apparent polarization of views is more about manufactured outrage, about knowingly taking an extreme position to provoke response, and that's become the dominant mode of discourse online, and from there leaked into RL. It's somehow more appealing to have an argument with radical disagreement than a more nuanced discussion where participants can both agree and disagree in parts.