I’ve always thought ‘absence of evidence is not evidence of absence’ is flawed for material truths because of the second law: presence of X, X being at different entropy from background, would necessarily produce evidence. No fire without smoke basically https://en.m.wikipedia.org/wiki/Evidence_of_absence …
This is the intellectual basis to Rumsfeld’s “unknown unknowns” - there’s no evidence for x but our paranoia dictates that we must act as if x is possible, maybe even likely.