Lots of things are unobservable though. Amplitudes of a wave function are unobservable. What does your idea of existence and relevance say about that? Why is co

Lots of things are unobservable though. Amplitudes of a wave function are unobservable. What does your idea of existence and relevance say about that? Why is constructibility of elements relevant for belief in a whole. You will never observe an amplitude, is the wave function then "non-real"? The inside of black hole is unobservable from beyond the event horizon. Does that mean the space isn't real? Why is this property of observability or constructibility of individual elements relevant for the existence of a set. Concretely. I believe in the reals because of taking analysis. I guess I don't understand the leverage of calling the reals a "leaky abstraction", it just reads like a skeptical argument taken too far. I hand you a box and say, "these are the reals, they behave this way". You respond, "I've looked in the box and almost all the elements have no recipe, this box doesn't exist." It seems like a non-sequitur to me.