Absence of Evidence (The limitations of science)

by dhw, Wednesday, February 27, 2008, 18:43 (6114 days ago) @ George Jelliss

George Jellis challenges the principle of "absence of evidence is not evidence of absence", quoted by John Clinch in defence of abiogenesis. I agree totally with George's challenge, and suggest we should settle for the fact that absence of evidence is not evidence of absence or of presence. Then we can forget it. - George goes on to advocate probabilistic reasoning, "which is often found unsatisfactory to those who seek certainty and want everything to be clear in black and white, yes or no, true or false terms." I'd have thought most agnostics would be all in favour of probabilistic reasoning, as opposed to "true and false". But George then says: "the problem with agnosticism is that instead of accepting that there is a whole gradation of probabilities (from 0 = certainly false to 1 = certainly true) it recognises only the midpoint (1/2 = 0.5 = we don't know for certain)." - First of all, I'm not convinced (or don't know for certain!) that 0.5 = we don't know for certain. Most contributors, including yourself, seem to agree that in the context of theism versus atheism, we are not dealing with knowledge but with belief, and that "knowledge" is impossible. By that definition, we would all be agnostics. I think the definitions should make this clear: 0 = believed to be false; 1 = believed to be true; 0.5 = neither believed nor disbelieved to be false or true. (As usual, I'm referring to the 'unofficial' form of agnosticism as opposed to the 'official' Huxley form.) - Secondly, I myself have no difficulty recognizing that many people have less than a 100% belief or disbelief, but if on the scale of probabilities I find myself stuck at 50%, why is this a problem? And for whom? It would certainly be a problem for me to choose and defend one unlikely explanation and exclude other possible explanations. A more general "problem" may well arise if someone insists that one explanation is more likely than any other, and that the probability is so great that other explanations can only come from people who need to "grow up" or ... in the case of religious fundamentalists ... need to be taught a lesson. - Thirdly, may I point out that the thread under "Atheism" deals precisely with gradations, and I'm glad we have come back to the subject. I suggest that we reopen this thread, as it has a number of important implications. For instance, if you rate yourself as 75% convinced that life began by chance, exactly what does the other 25% consist of? I would like to think that the sliding scale discussed here would create areas of common ground and a basis for tolerance in place of the one-sidedness that sometimes spills over into what Peter P. calls bigotry. - Having said that, though, I find it stimulating and illuminating to be told why one explanation seems more likely than another ... that after all is the purpose of our exchanging viewpoints ... and who knows, I may even one day be persuaded to shift from my 0.5.