Appeal to ignorance

Etymology

The Latin name "argumentum ad ignorantiam," another coinage of John Locke, means an appeal "to ignorance" — to what is not known. The error treats a gap in knowledge as if it were positive evidence. Not yet disproven is not the same as proven.

noun phrase · /uh-PEEL too IG-nuh-runs/
Treating the absence of evidence against a claim as proof that it is true, or vice versa.
What it names
Blocks the move that turns "you can’t disprove it" into "therefore it’s so."
Example
"No one has shown the site isn’t haunted, so it must be" is an appeal to ignorance.
Related idea
Like the appeal to authority, it was one of Locke’s named "ad" arguments, but here the lever is missing knowledge rather than borrowed prestige.