Probability is the measure of belief, specifically rational belief. That is, belief based on data. It does not give any guarantee, however. It is a game. It is a logical game. The scientists have been clever but you cannot keep on guaranteeing -- at some point you belief something not based on any rational. (And it's not to say that our beliefs do not arise from supra-rational).

All and all, probability is an exercise in logic.

The logicians have arrived at certainty, but not about the world.