Appeal to ignorance
Also called: Argument from ignorance, Ad ignorantiam
Claiming something is true because nobody has shown it false, or false because nobody has shown it true.
How to spot it
“Prove me wrong” or “you can't prove it isn't” offered as the proof.
Example
“Nobody has ever proved there isn't a tax on moon rocks, so there must be one.”
How to answer it
Not being disproved isn't proof. Ask for positive evidence: the one making the claim has to support it. A missing sign counts only where you would expect to see one if the claim were true (see argument from silence).
Related
- Argument from silence: Taking the lack of a record or mention as proof something didn't happen.
- Argument from incredulity: Concluding something is false because you can't imagine how it could be true.
- Shifting the burden of proof: Claiming something is true because it hasn't been disproved, and asking others to disprove it.