Physics is shit

So you have this gravity law. But does particle attract itself?

I.e. does it work like (mapcar (lambda (X) (gravity X Xs)) Xs) or X should be excluded from Xs, before gravity applies?

>>31
Yeah, that makes sense. The trick with proving an impossibility is that you need some assumptions to establish the contradiction. And this gets difficult when you don't know if your assumptions are correct or not. Is the assumption false, or is the thing your are trying to prove to be impossible false? But you can still show that they can't coexist. But then if a theory was to contradict itself, then there is no issue with trusting the assumptions. The theory packages all of the assumptions, and proves itself to be inconsistent with itself.
In a way, logical contradictions or internal inconsistencies can be used to rule out some theories or to show that some properties are literally impossible.

In practice, we tend to use models that we know wrong in certain contexts because we either don't have anything better (yet) or that they are just accurate enough in the context they are applied and we can live with some error we can estimate.