I spent much of 2018 on a quest to try to set my internal sense of judgment and partisanship aside, and just focus on understanding why people come to believes that appear to be completely irrational, and why otherwise intelligent and well-meaning people can be so at odds in their beliefs.

I'm coming strongly to similar conclusions - people are poor thinkers and totally unaware of this fact. They're not self-critical, but they are very critical of anyone who disagrees with them.

I summed it up in a quickie comment recently that has stuck with me. "Nobody thinks they're a racist. When they say racist things, they don't think they're being racist. They think they're being reasonable."