any sufficiently advanced theology is indistinguishable from bollocks

There's been an interesting discussion going on at, variously, Richard Dawkins, PZ, Ophelia and Jerry's blogs the last few weeks, and it revolves around the following seemingly simple enough question: what evidence would convince you that there was a god, or more generally, that there was a supernatural realm of some sort? I mean, we're all rationalists, right? You know, well aware of the tentative and provisional nature of all scientific conclusions, and absolutely prepared to abandon any particular theory if a better one with more explicative and predictive power comes along.

But there's a problem with this. Let's take as an example, for the sake of argument, the off-the-cuff suggestion offered here of a 900-foot Jesus suddenly appearing, parting the Atlantic to allow a London to New York drag race and then turning the losers into pillars of salt. Let's say this was witnessed by thousands of people, covered live by all the major TV channels, photographed from various aircraft, that sort of thing. So what would we conclude? Well, the scientifically-minded would say: wow, that ten-thousand-foot wall of water is pretty impressive, I wonder what's holding it up? Some sort of force-field? A grid of invisible carbon nanotubes? Clearly water is not sentient, so it can't know the will of God, however awesome, so there must be something physical doing it. And let's say that we can't detect the mechanism, try as we might. What do we then conclude? Remember Clarke's third law: any sufficiently advanced technology is indistinguishable from magic.

Surely it would be more likely that this eye-boggling display was simply some previously undetected alien presence either demonstrating their superior technology, making use of laws of physics currently unknown to us, or just fucking with us by inducing some sort of completely convincing mass hallucination. To put it another way, if we managed to travel back in time to the Middle Ages with a couple of helicopters, an iPod and a microwave oven, we would be performing feats that would class as "supernatural" by any reasonable definition available to those around at the time. Would that then make us gods? In other words, if we see something doing something that seems to contravene the laws of physics, do we fall to our knees and start worshipping it, or do we conclude that our understanding of the laws of physics must be incorrect, or at least incomplete, and set about trying to correct it?

Further complicating things is the inability of anyone claiming the existence of a god to produce a coherent definition of its characteristics. Even simply-stated and fairly standard notions like omnipotence dissolve into incoherence when examined closely.

So it seems practically impossible even to conceive of anything that would not be better explained by prankster aliens or sudden brain injury. And yet it seems wrong, somehow, completely to discount even the possibility of being convinced. That seems to be playing into the hands of the atheism-as-religion, science-as-dogma brigade. So what position do we take?

I think it's intellectually consistent to say: in principle I could be persuaded of God if the evidence were incontrovertible, but I cannot imagine what form that evidence might take, and all the scenarios that have ever been presented would be better explained in other ways.

In a way that lets the theists off the hook a bit, though, so I think it's also intellectually consistent to say: before I even commit to the first bit above, define your God and his properties in a way that is not self-evidently internally inconsistent, absurd, or so vague as to be meaningless. Then we’ll talk more.

The disagreement seems to be over whether the second bit can ever be satisfied, and therefore whether we ever get to proceed with the first bit. Maybe a useful way to look at it is to think of a 3-D object interacting with the inhabitants of Flatland. The 3-D object might be magnificently (let's say) spherical, but all the residents of Flatland are ever going to see of it is a circle where it intersects their 2-D world. So how would they tell the difference between that and, well, a circle? Flip the analogy back and ask yourself: if the entity behind the 900-foot Jesus was really "beyond" the laws of physics in some way, how would we know? How would we measure it? How would we even perceive it? To put it another way, as one of the commenters here did, you might rephrase the question (my emphasis) as: "What evidence would it take to satisfy me that what is by definition false is in fact true?"

Let's not forget, also, that proof is antithetical to faith. Remember the Babel fish.