Expertise is just experience. Which only applies in situations which you have seen before. Or put another way: that one is a good plumber does not mean one is

Expertise is just experience. Which only applies in situations which you have seen before. Or put another way: that one is a good plumber does not mean one is a good heart surgeon. Yet for some reason we assume that is the case in intellectual pursuits because we don't see the stuff ideas are made of.