Fallacy · Leaning on the wrong support
Appeal to ignorance
Also called: Shifting the burden of proof
Claiming something is true because it has not been proved false, or false because it has not been proved true.
What it is
Not knowing is not evidence either way. Whoever makes a claim owes the reasons for it; the other side is not obliged to disprove it. Otherwise any claim, however wild, would stand until someone took the trouble to refute it.
An example
“Nobody has proved there isn’t a monster in the lake, so there could well be one.” Lack of disproof gives no reason to believe in the monster.
How to spot it
The argument rests on “you can’t prove it isn’t”, or “there’s no proof it is”.
How to answer it
“You’re the one making the claim. What’s the evidence for it?”
When it is not a fallacy
Absence of evidence counts when we have looked properly where evidence should be. A careful search of a room that finds no keys is good reason to think they are not there.
Printable sheet of all fallacies
Cite or share this page
A plain reference you can paste into notes or an essay:
Quest2Reason. “Appeal to ignorance.” https://quest2reason.com/learn/ideas/fallacies/appeal-to-ignorance. Accessed 13 November 2026.