proving non-existence : when an arguer cannot provide the evidence for his claims, he may challenge his opponent to prove it doesn't exist (., prove God doesn't exist; prove UFO's haven't visited earth, etc.). Although one may prove non-existence in special limitations, such as showing that a box does not contain certain items, one cannot prove universal or absolute non-existence, or non-existence out of ignorance. One cannot prove something that does not exist. The proof of existence must come from those who make the claims.
A logical fallacy is, roughly speaking, an error of reasoning. When someone adopts a position, or tries to persuade someone else to adopt a position, based on a bad piece of reasoning, they commit a fallacy. I say “roughly speaking” because this definition has a few problems, the most important of which are outlined below. Some logical fallacies are more common than others, and so have been named and defined. When people speak of logical fallacies they often mean to refer to this collection of well-known errors of reasoning, rather than to fallacies in the broader, more technical sense given above.
Fallacy: Questionable Cause Description of Questionable Cause This fallacy has the following general form: