In 2011 I wrote:
The conventional theory of politics is that people figure out by themselves what their views are on various issues, and then they decide what political party to belong to based on their views. This conventional theory is wrong. It works the other way around. People know what team they belong to (Democrat, Republican, liberal, conservative, etc.) and then they adopt the views of their team.
Smart people tend to have more consistent views on political issues (consistently liberal or consistently conservative, for example) because instead of using their intelligence to independently figure out the correct views on issues, they use their intelligence to figure out what their team believes. Smart people tend to be more conformist then dumb people.
A reader emailed me a link to a blog post at Marginal Revolution about a research paper from Yale Law School that backs me up. Half Sigma was right once again. To quote from the paper:
Only the third theory—the “Expressive Rationality Thesis” or ERT—was fully supported by the study. That theory alone predicted both that ideologically motivated reasoning would by symmetric and that it would be amplified by higher CRT. Those hypotheses reflect a theory that sees ideological motivated reasoning not as a reasoning deficiency but as a reasoning strategy suited to the interest that individuals have in conveying their membership in and loyalty to affinity groups central to their personal wellbeing.
That’s a complicated way of saying that people first belong to a group, and then adopt beliefs held by the group. I disagree with calling this behavior “rational.” While one can make a valid case that it’s rational to at least present to other people in your group that you share their beliefs, in reality the vast majority truly believe their group’s beliefs. It’s instinctive behavior and not something that people give rational thought to.