The Implications Of Jesuses, Tap-Dancing Or Otherwise
PZ's post regarding the fundamental unprovability of the existence of God brought to mind a vignette from a couple of years ago. I was walking to work and was stopped by a couple of young-ish people (high-schoolers perhaps) who asked me if I believed in God. When I replied that I didn't they followed up with a question about what evidence I'd need to change my mind, to which I answered something along the lines of "documented evidence of the supernatural" would be a good first step. PZ's assertions notwithstanding I still think there's merit to that answer.
Let's stop and consider the example of a tap-dancing Jesus. What are we to make of it if the aforementioned fellow suddenly poofs into existence, does a little soft shoe, maybe performs assorted miracles, and then disappears into thin air? Our first step, certainly, would be to eliminate the many natural phenomena which might serve to explain our observations. But after we've determined that it wasn't done with smoke and mirrors and that we're not experiencing a mass hallucination, what then?
Michio Kaku provides a helpful framework which can be used to think about this sort of thing. He has identified three classes of probability regarding technology, the most improbable of which, "Class III", contains phenomena like perpetual motion and precognition whose existence would violate established laws of physics. If the hypothetical Jesus were to perform one of these Class III feats it should, in the very least, give us pause. The question is what sort of pause, exactly, should it give us?
I'm with PZ in that the existence of a Class III Jesus (not to be confused with a level 80 Jesus) wouldn't, in general, prove the existence of any particular god and would deal a fatal blow to many theologies. At the same time we'd have found ourselves in the presence of a chap who does things which are inconsistent with our fundamental understading of how the universe works; what to make of that? As PZ points out "god" is a hopeless muddled and malleable concept; venture down that road and you'll end up in a hopeless semantic quagmire. But its facile to say that the existence of such a fellow should be dismissed as epistemologically meaningless; were he to turn up tomorrow the metaphysical implications thereof would be absolutely staggering.
So, while it may be true that there's no possible evidence for the existence of "god", it is possible to prove the existence of beings with abilities that are "god-like".