We have proofs for every occasion, or rather, every occasion we can come up with.
Proofs of the existence of aliens, the afterlife, and the meaning of life are available upon request.
But be warned, our proofs are often completely and utterly fabricated.
We have proof that the chances of winning the lottery are higher than they actually are.
And also, proof that cats are actually aliens in disguise.
Because, clearly, they have nine lives.