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If I haven't looked in my desk drawer, this is not evidence that it's empty. It's only evidence that it's empty if I open it and don't see anything. Or, put a
by amalcon 13y ago
If I haven't looked in my desk drawer, this is not evidence that it's empty. It's only evidence that it's empty if I open it and don't see anything.
Or, put another way: The real world isn't boolean. A and Not-A are not the only options; there's also "I don't know."
The last case there is what's generally referred to when people say that absence of evidence is not evidence of absence.
- johnpmayer 13y agoAlso known as criticisms of the Law of Excluded Middle.
- Gormo 13y agoOr to put it another way, the world isn't deterministic. A and not-A aren't the only options; there's also "sometimes A, sometimes not-A, depending on where in the probability distribution each situation falls". And here's where we need to distinguish knowledge of evidence from evidence itself; if you haven't collected any observations, then not knowing of any evidence doesn't imply that evidence is actually absent. In other words, "I don't know" isn't actually absence of evidence.