Us vs Them would suggests two parties, not one-dimensional politics. If people are forced into coalitions, then the variation inside the coalitions should be orthogonal to the direction between the coalitions. But it seems to me that most of it is along the axis separating the parties. Maybe that's an illusion because it is salient - who is a swing voter, who can negotiate with the other party, etc. Moreover, when I look at a European country, I see a bunch of parties strung out along a single axis. This seems less likely to be an illusion, though I have less experience with European politics. How is this driven by Us vs Them? Slovakia has a small libertarian party. So does America. The Slovak party is larger, partly because small parties are viable in a proportional system, and maybe also for other reasons reflecting a difference between the populations. That doesn't necessarily mean that the correlations between political positions are different between the two countries. Moreover, the topic of the post is factual beliefs. Even if the structure of the coalitions causes people's policy preferences, that is a weaker claim than that it causes their factual beliefs. Maybe free-market Americans join the Republican party and come to oppose gay marriage and drug legalization, whereas free-market Slovaks join a different party with different influence. But I rather doubt that positions on gay marriage are driven by factual beliefs. Drug legalization might be, but it is probably a minor belief, a higher-order correction, compared to the important beliefs that drive their free-market positions. What I said I don't believe is that different coalitions drive the correlations between factual beliefs.