Tuesday 2 September 2014

ECREE and the Argument from Miracles

When faced with miraculous testimonies, skeptics often cite the mantra 'extraordinary claims require extraordinary evidence'. In turn believers charge skeptics of being overly skeptical, and arbitrarily setting a higher bar for claims to the supernatural. And, often times, they are right. If you ask most skeptics why extraordinary claims require extraordinary evidence, or what it is to be an extraordinary claim, they usually aren't able to explain themselves very well. But, I think, there is some truth to this mantra, and it can be fleshed out in a mathematically rigorous way. Enter Baye's theorem, which states:
Pr(A|B) = Pr(B|A) * Pr(A) / Pr(B)
Once you're aware of it, all the pieces fall into place. An extraordinary claim is simply one with a very low prior probability. Extraordinary evidence is simply evidence that is very strong, having a very high conditional probability. It's almost self-evident that very improbable events require very strong evidence before we can reasonably accept them, but Baye's theorem shows us why. Suppose A is an extraordinary claim (having very low prior probability), and B is an established fact which isn't incredibly probable or improbable. The ratio Pr(A) / Pr(B) is going to be very close to zero, which will cause Pr(A|B) to be a very small fraction of Pr(B|A). If Pr(B|A) isn't incredibly large to begin with, the fact that B is evidence for A is going to be practically insignificant.

Now let's turn our attention to a particular miracle—probably being the most influential—the resurrection of Jesus of Nazareth. I'll admit, there is interesting evidence for this miracle. It's enough, at least, to catch ones attention. But rationalize belief? I'm not so sure. The problem is precisely that extraordinary claims require extraordinary evidence; while the evidence of Jesus' resurrection seems fairly strong (if similarly strong evidence was presented for a more mundane claim, you would surely be convinced), it doesn't seem strong enough to overwhelm the initial implausibility of the claim.

Think about the sort of claim being made, that someone rose from the dead after three days of rot and decay. In all of our experience with death, people tend to stay dead. Even under ideal conditions where the body has been frozen and there is a team of doctors standing by, resurrection is still incredibly difficult. But in all of our experience with death, never have we observed someone coming back from the dead after three days (excluding this one case). In fact, over a hundred thousand people die every day, and we never see anyone raised as Jesus is said to have been. It then seems we must think that resurrection after three days is really really really improbable.

Apologists will agree to an extent, but say drawing conclusions about Jesus' resurrection isn't fair. This is, after all, supposed to be a miracle, which suggests it occurred by supernatural means. But even here still, one can assume God exists (and has the power to raise the dead), and still point out that it happens (if at all) at a frequency of near zero. Even under the assumption of classical theism, a resurrection of this sort seems incredibly improbable. Apologists will retort that Jesus was a special case; he was, after all, the son of God. But herein lies the problem. If one must assume the existence of a god that wants to raise Jesus in particular, but not anyone else, then they're practically assuming the Christian god. There isn't any other god we know of that would have special reason to bring back this one particular Palestinian, two thousand years ago.

And this is fine for them to assume, given that Christianity itself is a fair assumption. But what isn't permissible is them using the supposed fact that Jesus rose from the dead as evidence for Christianity as apologists typically do. They are committing a sort of question begging fallacy. They want to argue that Jesus' resurrection is evidence for the Christian god, when they must presuppose something very much like the Christian god exists to even establish that Jesus rose from the dead in the first place. But if that's the case, then the fact that Jesus rose from the dead offers nearly nothing in favour of Christianity. It can't raise the probability of Christianity significantly more than what is already granted.

All this is to say that there is still a wide chasm between establishing classical theism, and establishing Christian theism. And, it can only be crossed by showing that the god of classical theism would probably have motive to raise Jesus, in particular, from the dead. But this in of itself seems just as difficult to defend as anything else and, as such, it seems the prospect of defending Christian theism by use of an argument from miracles is bleak.