Argument From Ignorance
(argumentum ad ignorantiam)
Definition:
Arguments of this form assume that since something has not been proven false (or cannot be), it is therefore true. Conversely, such an argument may assume that since something has not been proven true, it is therefore false. (This is a special case of a false dilemma, since it assumes that all propositions must either be known to be true or known to be false.)
As Davis writes, "Lack of proof is not proof." (p. 59)
Examples:
- (i) Since you cannot prove that ghosts do not exist, therefore they must exist.
- (ii) Since scientists have not proven that global warming will occur, therefore it won't.
- (iii) Fred said that he is smarter than Jill, but he didn't prove it, so it must be false.
Proof:
Identify the proposition in question. Argue without evidence and proof no claims whatsoever can be derived on the subject. Such a claim is neither true nor false, but arbitrary.
References:
Copi and Cohen: 93, Davis: 59, Rand: 79
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