Really, if we have to go about proving that everything doesn't exist or that things won't happen, we won't be able to leave home without being unprepared for something. I mean, do you carry around a bottle of maple syrup wherever you go? No? Then what if intergalactic space waffles invade tomorrow?

The only acceptable outcome of unprovable arguments is to try to find some way to exit the argument with both people respecting each other. If you can't do that, everyone is missing the point.