It's often claimed that you cannot prove a negative. On the surface, it seems to be true: if Person A says “I think Unicorns exist” and Person B says “I don’t think unicorns exist”, it’s pretty clear that Person B is going to have a hard time proving that there isn’t a God. However, if you look a little closer, it actually depends on the nature of the negative statement being made. Here are some negative statements that can be proven very easily: Five is not equal to four The ancient Egyptians did not watch Seinfeld The tsetse fly is not native to North America Clearly, it’s possible to prove a negative statement. The real problem here is clearly the nature of the positive statement being refuted. When a person asserts that X exists, and he does not specify the nature of X – that is, is X small, large, blue, red? And where is he? Of course it is not possible to prove that X does not exist, if X is a thing that has no definition, no characteristics, and no location. In fact, you can prove just about any kind of negative you can think of – except for (surprise!) the non-existence of mystical beings. When you get right down to it, the statement “you cannot prove a negative” is really just a different way of saying “You can’t prove me wrong because I don’t even know what I’m talking about.” Logical statements have to abide by certain rules and restrictions. In order for a statement to be logical, it must be falsifiable, which means that it has to be presented in such a way that it could be proven incorrect. A statement is not logical if it cannot be tested to make sure it is true. The statement "X" exists is therefore absurd and nonsensical. No one even knows what X is supposed to be.