Do you think the Matt Maroon quote is correct? I'm not even quite sure what he's trying to say, because he equivocates between denying that you can accurately read the world through the lens of other people's behavior or affect (you can't know if their poker hand is actually good), and denying that you can accurately read other people's minds through the lens of their behavior or affect (you can't know if they actually know the answer to your legal question). Or maybe both?

Anyway, I'm not even sure how accurately you can tell if they think their hand is good. But putting that aside, surely there are some things you can learn about people -- and even, by implication, about the external world -- from their behavior, even when they themselves do not know (do not "perceive") these things?