I put a comment against the QOTW. Basically, it's whether one wants provable behaviour in all circumstances, or whether pragmatism rules. There are very many things that "work", even though you can't prove that they always will. Indeed, there are many useful things which one can prove have a small (hopefully thermodynamically small) chance of total failure.
I can't prove that my head won't fall off before I finish typing this. It's thermodynamically possible, but so unlikely that it won't happen even given a googleplex of universes to try it out i