Appeal to Ignorance
Treating a claim as true because it hasn't been proven false (or false because unproven).
- informal
An appeal to ignorance (argumentum ad ignorantiam) takes the absence of evidence against a claim as proof that it's true, or the absence of evidence for it as proof that it's false. But not having found something is not the same as showing it doesn't exist — a lack of evidence simply leaves the question open.
Examples
- “No one has ever proven that ghosts aren't real, so they must exist.”
- “Nobody has shown the new food additive is harmful, so it must be completely safe.”
Why it works & how to counter
Persuasive because an open question feels uncomfortable and “unproven” sounds like a verdict. Counter it by pointing out that absence of evidence isn't evidence either way — the claim still needs positive support.