In Defense of Hume, Part 3: Hume's Maxim On Human Testimony to Miracles as a Foundation for Religion
"That no testimony is sufficient to establish a miracle, unless the testimony be of such a kind, that its falsehood would be more miraculous, than the fact, which it endeavours to establish; and even in that case there is a mutual destruction of arguments, and the superior only gives us an assurance suitable to that degree of force, which remains, after deducting the inferior." When anyone tells me, that he saw a dead man restored to life, I immediately consider with myself, whether it be more probable, that this person should either deceive or be deceived, or that the fact, which he relates, should really have happened. I weigh the one miracle against the other; and according to the superiority, which I discover, I pronounce my decision, and always reject the greater miracle. If the falsehood of his testimony would be more miraculous, than the event which he relates; then, and not till then, can he pretend to command my belief or opinion. #91Later Hume tells us the only reasonable conclusion one can draw from his maxim: "Therefore we may establish it as a maxim, that no human testimony can have such force as to prove a miracle, and make it a just foundation for any such system of religion." (#98). The fact that a miracle requires extraordinary evidence over and above the fallibilites of ordinary human testimony is not an unreasonable demand on Hume's part. It's the nature of the beast. The consistent workings of the natural world preclude miracles from happening. This natural world order is known with as much assurance as anything that can be known. It's so well established that natural laws have been derived from it's regularity and used daily in our laboratories and factories. That human testimony is fallible is also known with a great deal of assurance, especially with the discovery of a great many cognitive biases. So we need more than just human testimony to accept that a miracle happened. Human testimony alone isn't enough to overcome what is known about how the world works. Given the nature of the world and the fallible nature of ordinary human testimony, we need sufficient objective evidence over and above human testimony (hence, called extraordinary evidence) to corroborate that a miracle occurred.
All you need to consider is what you'd think if someone testified that his amputated limb regenerated itself, or if a woman testified she gave birth to a baby deity as a virgin! Would you believe their testimony? What if a few others said the same thing? Here's the kicker: Human testimony, second- third- and fourth handed human testimony in the ancient pre-scientific world, where miracle claims were abundant without the means to discredit them, is all we have when it comes to the miracles we find in the Bible and the religions founded on it.
You can read Hume's Maxim in context below (#99-100). Upon doing so let's be done with the claim that Hume's argument is an a priori one that admits of no possibility of a miracle. It's one of probabilities all the way down. It's about human testimony to miracles in a world that precludes them as the foundation of a religion. And the kind of human testimony considered to be extraordinary in nature just does not exist! It could exist. That it doesn't is not Hume's fault.
The problem with Hume's argument therefore, is that miracles just don't happen. For if they did believers wouldn't object to it. It's precisely because believers want to believe that they try to find a way around it, even if it requires an intellectual sacrifice. Say it isn't so! Otherwise they would agree with Hume's reasonable demand then go on to present sufficient corroborating objective evidence showing the miracles of their religion really did take place. The fact that corroborating evidence does not exist is why believers must object to Hume's rock solid maxim. So Christians have a choice to make. Either 1) biblical miracles did not take place, so there's no reason to believe them, or 2) miracles did take place, but there's still no reason to believe them. Given that Christians only have the evidence of human testimony in the Bible, this is the choice forced upon them. So choose. In doing so, don't go nutty on us as some others do.