I think a lot of the flaws of rationalism come in the form of using discrete logic to argue about the world. So many arguments end up as definition errors: the argument is nonsensical because of a deeper truth. For example, consider anything about gender. The arguments usually start as "there's male and female sexes, so if you aren't male you must be female." A very simple A and B, so if not one it's the other. Well the very definitions of the terms defy easy categorization. For example, people like to talk about chromosomes. This is what I call the chromosomal theory of sex, which is basically like newton's laws, which means they're mostly kind right, except when they're wrong, and then they're very wrong. It's a short cut: the biological reality of what it takes to turn a chromosome into biological sex is very complex, and mostly doesn't really depend on the exact DNA much of the time. A lot of this depends on stem cell differentiation which is only starting to be better understood right now. ​ The bottom line is that rationalists as far as I am concerned are people who want to simplify the world into neat little logic puzzles that are easily solved (see: the obsession with game theory), and are uninterested in the complexity and richness of life. A lack of curiosity is a defining factor imo. After all, if I discover that a rationalist is using game theory to predict me then I'll pick a non-optimal approach just to fuck over their prediction, because I like messing with people. And if I think they are expecting that then I'll do the opposite or chose a random choice. Good luck mathing THAT you fuckers.