It's some combination of reasoning and memory. But whatever it is, the thing that we call intelligent has to perform better than most people at relevant tasks.

It's some combination of reasoning and memory. But whatever it is, the thing that we call intelligent has to perform better than most people at relevant tasks. It's interesting because some people are clearly better at thinking about very specific things. Like, is a chess champion the same kind of intelligent as a mathematician? I don't know, probably not.