This is one article in a series where author Jamie Carlin Watson discusses themes from his book Expertise: A Philosophical Introduction. In this post he lays out some difficulties with the idea that propositional knowledge is secondary to what is most fundamental to expertise, namely practice. In particular, it seems, some people become 'experts' without any practice at all. In a follow-up post, he suggests that "expertise is not merely having knowledge or a certain level of skill. It is, instead, a way of having them that emerges through training in that domain. In other words, expertise emerges through what sociologist Harry Collins and Robert Evans call 'linguistic immersion'." Now I do think there's something to that notion. But it's not the whole story either.