Must everything have a cause? Or are spontaneous events possible, things that arise without any cause? First, it seems clear that whatever exist must have an effect of some sort on other things, otherwise they cannot be called real. Claiming otherwise is like saying that an infinite number of fictitious concepts really do exist, but they don't matter since they have no effect on anything. It's sort of a waste of words. So to exist is to have an effect and be a cause of some sort. The logical claim is that the existence of a cause implies the existence of its effect, or for short: cause implies effect. Unfortunately the reverse equivalent of this claim is "no effect implies no cause" and not "effect implies cause". It's too bad, but we cannot conclude that the existence of an effect implies the existence of a cause, so we cannot conclude that all that exists had a source. Not from the reasoning of the previous paragraph anyways. We only see that it seems to be the rule, but is there some logical proof that this is always so, beyond our common sense? Problem is, our common sense is just common, it is not a proof of anything. When we look hard enough, we usually find causes for almost everything we observe. But not always, research does not always bear fruit. Sure, there may also be theories a-la-QM that seem to work most of the time with certain postulates, but again a theory is not a final proof, theories are refutable. The question is: is there a logical necessity for everything to have a cause? So far, I have not found a way to either prove or disprove the possibility of spontaneous events. Anyone?