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.)
I'm not sure how useful this is, and I feel odd posting it this way (Intuitive Rationality?), but there is a 'feel' to when there is a fallacy camouflaged in the discussion. If the reader could learn to pay attention to it and dig for it when they feel it, I would consider that a worthwhile book.