Tweeglitch asked:

Set me straight please. Why isn't absence of evidence evidence of absence? If there is no evidence
available in support of the existence or non-existence of some thing then what is the proper attitude to
take to the question of its existence? Is it to say that it might exist? It can't be practical to act on this
given all the 'mights', all the things that could be imagined which may or may not exist with nothing to
support the truth of either. But to ignore the possibility (unknown as it is) by not acting on it doesn't
seem right either; one's attitude would be the same as if it doesn't exist without actually saying so. So
why not just say so? The model of the universe I use to navigate the world around me can only be
built of, and updated by, evidence if I want it to be the truest reflection of what's actually out there. So
if I detect no trace of some thing then that thing has no place in the model.

============

But surely you can think of situations in which, without evidence, it is clear that something is the
case... a murder in which there is only one reasonable suspect, but where there has been no
evidence found. Usually this is an unstable situation, i.e., evidence willbe found. But not always. To
put it another way, how exactly do you prove a negative?

But let's address your question directly: is the absence of evidence for — what? Another parallel
universe? A god? Extraterrestrials? — evidence of their absence? Well, how about aliens? We have
no evidence for the existence of aliens (no, sorry, all you UFO enthusiasts out there, read the
Skeptical Inquirer). So are there no aliens? Well, given the size of the universe, etc., that seems
utterly, absurdly, unlikely. So we have to say that at this point we just haven't explored enough of the
universe to say one way or another, and that all the evidence for the origin of life here on earth
indicates that it could happen somewhere else, that there shouldbe extraterrestrials. But that's just
inference, not evidence.

What about gods? I'm not even sure I want to do this again... I've done it so much here. I'll just say
that I think the evidence, such as it is, for Jupiter, Krishna, Thor, Allah, Osiris, Yahweh, Astarte, and
so forth is all equally strong (equally weak, actually). So it all sort of cancels out, doesn't it, since each
has implications contradictory to the others. Therefore, even if you assume evidence for these and
the multitude of other gods which humans have believed in, you're left with a category of possibilities
which does not seem a reasonable one. So we go on to other categories. But again, how do we prove
that Ra, for example, did not create the universe? I know of no such proof, and thus again we're left
with processes of inference.

So we have to admit that while logical positivism is too strong, since it would seem to eliminate things
like extraterrestrials, equally, simple belief or even some degree of "evidence" is too weak, since it
would leave us arbitrarily worshiping some god, or maybe a different one every day, or whatever.

What to do, then? I'll tell you what: do science. How do you do that? I'm sorry but I just cannot
condense that into a paragraph. Read this: Kitcher, P. The Advancement of Science; Science without
Legend, Objectivity without Illusions.New York, NY: Oxford University Press, 1993. It's not an easy
book, but it will give you some answers, I think.

Steven Ravett Brown