The argument from ignorance (or argumentum ad ignorantiam and negative proof) is a logical fallacy that claims the truth of a premise is based on the fact that it has not (yet) been proven false, or that a premise is false because it has not (yet) been proven true.

It is a common human’s logic fallacy, which simply states:
i dont know what that is… in which case it must be this or that…

It is often used as an attempt to shift the burden of proof onto the skeptic rather than the proponent of the idea. But the burden of proof must always be on the individual proposing existence, not the one questioning existence.

Ignorance is ignorance; no right to believe anything can be derived from it. In other matters no sensible person will behave so irresponsibly or rest content with such feeble grounds for his opinions and for the line he takes.

A common retort to a negative proof is to reference the existence of the Invisible Pink Unicorn or the Flying Spaghetti Monster as just as valid as the proposed entity of the debate. This is similar to reductio ad absurdum, that taking negative proof as legitimate means that one can prove practically anything, regardless of how absurd.

A religious apologist using the argument from ignorance would state something like, “the existence of God is true because there is no proof that the existence of God is false”. But a counter-apologist can use that same “argument” to state, “the nonexistence of God is true because there is no proof that the nonexistence of God is false”. This immediately demonstrates how absurd the argument from ignorance is by turning the tables on those who use this “argument” fallacy, like some religious apologists.