One Argument against an Army, Politics is the Mind-killer and related posts. (Actually, I'm surprised those posts don't reference each other, in my mind they're pretty close.)
Politics is probably the domain where I see the most emotional thinking around me (probably because people have little incentive to be actually right, and strong social incentives to go align with their peers).
Followup to: The Most Frequently Useful Thing
What's the number one thing that goes into a book on rationality, which would make you buy a copy of that book for a friend? We can, of course, talk about all the ways that the rationality of the Distant World At Large needs to be improved. But in this case - I think the more useful data might be the Near question, "With respect to the people I actually know, what do I want to see in that book, so that I can give the book to them to explain it?"
(And again, please think of your own answer-component before reading others' comments.)