Appearance in Reality deals with this question. You rely on instruments and everyday experience to verify your theories, but these theories are about unseen things that seem to have very strange properties. What’s the relationship between the appearance of things and their reality?

Metaphysics in that sense is really inescapable. Everybody poses these questions to themselves, but when people recognize that they've run into a metaphysical problem they typically say, “oh okay, that's just for the philosophers,” and they walk away from it, not realizing that they’ve actually taken a philosophical position already.