Description: Demanding that one proves the non-existence of something in place of providing adequate evidence for the existence of that something. Although it may be possible to prove non-existence in special situations, such as showing that a container does not contain certain items, one cannot prove universal or absolute non-existence. The proof of existence must come from those who make the claims.
I cannot prove that X exists, so you prove that it doesn’t.
If you can’t, X exists.
God exists. Until you can prove otherwise, I will continue to believe that he does.
Explanation: There are decent reasons to believe in the existence of God, but, “because the existence of God cannot be disproven”, is not one of them.
Sheila: I know Elvis’ ghost is visiting me in my dreams.
Ron: Yeah, I don’t think that really is his ghost.
Sheila: Prove that it’s not!
Explanation: Once again we are dealing with confusion of probability and possibility. The inability to, “prove”, in any sense of the word, that the ghost of Elvis is not visiting Sheila in her dreams is an impossible request because there is no test that proves the existence and presence of a ghost, so no way to prove the negative or the non-existence. It is up to Sheila to provide proof of this claim, or at least acknowledge that actually being visited by Elvis’ ghost is just a possibility, no matter how slim that possibility is.
Exception: If Ron were to say, “That is impossible”, “there is no way you are being visited”, or make some other claim that rules out any possibility no matter how remote (or crazy), then Sheila would be in the right to ask him for proof -- as long as she is making a point that he cannot know that for certain, and not actually expecting him to produce proof.
Tip: If you think you are being visited by aliens, gods, spirits, ghosts, or any other magical beings, just ask them for information that you can verify, specifically with a neutral third-party that would prove their existence. This would be simple for any advanced alien race, any god or heavenly being. Some ideas of things to ask for:
future lottery numbers (of course you will give all your winnings to charity)
answers to scientific problems that do have scientific answers, but aren’t yet known
exact details of major future events
But if these beings just tell you things such as:
passages / ideas from the Bible
whether you should take that new job or not
where you left your car keys
that they really exist, and others will continue to doubt you
that you should never question their existence
...or anything else which is just as likely to come from your imagination that is untestable and unfalsifiable, then you might want to reconsider the fact that your being of choice is really paying you visits.