Yes, I should have mentioned the Dunning-Kruger effect, and also studies that show we are more likely to vote for incumbents if our sports team has just won a game, and for challengers if it is raining. The list of our mental shortcomings is sadly very long indeed. It’s also true, as you note, that clever people are by no means immune — I think however that clever people make fewer obvious cognitive mistakes and are slightly more amenable (on average) to modifying their beliefs on the basis of new information. The most important thing, however, is for us to recognize our cognitive limitations and attempt to engineer mitigating structures. Only clever people are likely to engage in this effort as it’s highly likely less intelligent people simply won’t understand or accept the need to do so.