I would deem it impossible to prove that something does not exist. Therefore I depend on being able to prove that a particular thing does exist.

What can be problematic is proving the necessity of a thing that you cannot prove to exist. Why do you need to assume that there was something before time started. That does not make sense. It shows that we do not accept limits.

On another tack how can you ultimately prove that what you experience is not an illusion. You have to make some assumptions or else we could all equally well be hooked up to a machine in the 35th century experiencing the virtual reality equivalent of a historical documentary video!

I thinh it was Robert Heinlein who invented pan-dimentional multi-person solipsism.(spelling?)