It doesn't have to be explained why, it is. The why would be a separate question requiring reasoning. Things can be true without an explanation as to why they h

It doesn't have to be explained why, it is. The why would be a separate question requiring reasoning. Things can be true without an explanation as to why they happen. It's not an assumption as experience is not a choice, in fact experience is a prerequisite to then be able to assume (as well as to reason).