William Lane Craig is a Christian apologist and philosopher, famous for his debates with atheists. I do enjoy his debates: even if you don’t agree with Craig (or the atheist he is debating), there is value in the debate itself. For me, what’s most important is that the issues are constantly laid out in clearer ways, and debate is an engaging way to do this.
But here I wonder about Craig’s response to the common atheist aphorism, “extraordinary claims demand extraordinary evidence.” His response is that the proverb would prevent us from accepting that a particular ticket won the lottery, as the probability of any single ticket winning the lottery is very low. For him, one cannot just consider the inherent probability of a claim, but how improbable the observations we observe regarding the claim would be if the claim weren’t true. In the case of the lottery, it would be very improbable that a winner would be announced on the media if, in fact, that winner didn’t really win the lottery. So in this case, even if the probability of that person winning the lottery is very low, we can accept that she won.
The same goes for miracles like Jesus’ resurrection. Resurrections are improbable, but the odds of our relevant observations (the empty tomb, the resurrection appearances, the disciples’ radical belief changes) would be very improbable if the resurrection didn’t take place. Thus Craig argues that we can accept that Jesus rose just as we can accept that the lucky lottery ticket holder won.
I don’t disagree with Craig’s claim that explanatory power, discussed in the previous two paragraphs, is just as important as inherent probability. But that doesn’t disprove the aphorism. In fact, it’s completely compatible with it. The aphorism allows for the accumulation of evidence, that is, explanatory power, to override initial skepticism. It only requires that the evidence be extraordinary.
What the aphorism claims is that we can’t just look at evidence for a claim, expecting that if an amount of evidence is enough for one claim, it should be enough for every other claim. It points out that less inherently probable claims require more evidence that mundane claims. Claiming that I drove to work requires less evidence than the claim that I flew to work, using my arms as wings.
So here I think is where the real dispute is between Craig and skeptics. Skeptics think the inherent improbability of God’s existence or the resurrection of Jesus is so low as to require a very radical amount of evidence to overcome it. Atheists I’ve talked to or listened to online mention a universally observable breakdown of the natural order, something like what’s in the Book of Revelation, to meet the evidential burden: nothing less than that would suffice. That is, the skeptics focus on what they take to be low prior probabilities, generally seeing any currently attainable amount of evidence as insufficient. Craig, however, focuses on the explanatory power. But I think that both need to be considered.
One other note, skeptics do think God is very improbable; just as improbable as Zeus, Big Foot, or the Flying Spaghetti Monster. True, the last three are inherently improbable, but does that make God inherently improbable? That would depend on how similar God is to those things. I don’t see a great similarity. God is completely immaterial, while the last three are either unusual physical objects or physical objects embedded with divine characteristics. I don’t think you can compare them. So I would submit that God’s prior probability is unknown, and not low.