Absence of Evidence (The limitations of science)

by George Jelliss , Crewe, Tuesday, February 26, 2008, 20:58 (5902 days ago)

One or two contributors have cited the unaccountably popular principle that "Absence of evidence is not evidence of absence". - With respect I must challenge the veracity of this principle. - If there are no piles of dung on the doorstep, no large footprints on the carpet, and no sound of trumpeting from the kitchen, I feel justified in concluding that there is no elephant in the house. Of course I may then find that there is a small, well-behaved, house-trained elephant in the kitchen, but my surprise at finding it there will be justifiable. - Generally speaking, the absence of the most likely traces to be left by something are prima facie support for the likely absence of that something. This of course is 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. - Outside logic and mathematics (and even inside logic and mathematics sometimes) nothing can ever be absolutely certain. All our knowledge is based on assessment of probabilities. 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).