The Human Eye: A Double Standard?

[Mudhammam]

Absence of evidence is not proof of absence.....it sure as fuck is evidence of absence.

Not necessarily. That's a classic example of an argumentum ad ignorantiam.

Carl Sagan explains in his book The Demon-Haunted World:


Appeal to ignorance: the claim that whatever has not been proved false must be true, and vice versa. (e.g., There is no compelling evidence that UFOs are not visiting the Earth; therefore, UFOs exist, and there is intelligent life elsewhere in the Universe. Or: There may be seventy kazillion other worlds, but not one is known to have the moral advancement of the Earth, so we're still central to the Universe.) This impatience with ambiguity can be criticized in the phrase: absence of evidence is not evidence of absence.[3]


For instance, absence of evidence that it rained (i.e. water is the evidence) may be considered positive evidence that it did not rain. Again, in science, such inferences are always made to some limited (sometimes extremely high) degree of probability and in this case absence of evidence is evidence of absence when the positive evidence should have been there but is not.

Arguments from ignorance can easily find their way into debates over the existence of God. It is a fallacy to draw conclusions based precisely on ignorance, since this does not satisfactorily address issues of philosophic burden of proof. But null results are not ignorance and can be used as evidence to achieve a given burden of proof.

(bold mine)

You must define what causes or outcomes you would expect to observe if such-and-such were to exist in order to use the absence of those features as evidence that such-and-such does not exist.