Africa Speaks Reasoning Forum

The absence of evidence is evidence of absence, can this statement be true?

If we expect that something will have observable effects, should it exist? And if it doesn't have observable effects, does that mean it probably doesn't exist? The stronger our prior belief that something would, if it existed, have observable effects, the more absence of evidence is evidence of absence.

For example, does the absence of smoke over a forest. I’m looking out my back window and it is surely evidence of the absence of a major fire in the woods that sits in the back of my house. Obviously absence of evidence is evidence of absence is true.


But is it true only where "evidence" for something: a) hasn't been looked for in an effective way and (b) is such that, if it existed, it would not otherwise intrude upon our consciousness?