Over at the Secular Outpost blog, Keith Parsons has launched another thoughtful critique of the argument from miracles. True to the spirit of the skeptical empiricist Hume, Parsons doesn't deny the sheer possibility of true miracle claims but denies rather their plausibility in practice or demonstration. He argues instead that the empirical confirmation of miracles is possible only in principle, which in terms of Christian apologetics is "a pretty weak conclusion." Though his argument frankly deserves more than the brief riposte I will attempt here, I do hope to at least address one important sticking point.
To get past confusion arising from definitions, Parsons proposes a miracle be defined as the divine performance of an act resulting in a physically impossible event – "one that, while logically possible (i.e. the proposition asserting its occurrence does not entail a contradiction), is not realizable in the physical universe given what we know about the capacities and limitations of physical entities and forces." That sounds like a reasonable enough definition to get on with the argument.
So then, why should we think miracle confirmations cannot be had in actuality? Well, if I understand Parsons, the idea is that there is no precedent for a confirmed miracle claim, given that we use the same scientific and probabilistic methods that we use to confirm any other event. With this understanding in place one can see why Parsons might be initially skeptical. On a Bayesian reading of evidence, for one thing, the probability of any particular miracle testimony, regardless of whether a miracle has occurred, has to be quite low in order for the miracle claim to have any explanatory power; and given human nature the probability of such testimony is not all that low. But this doesn't mean that miracles are impossible to confirm, strictly speaking. As Parsons notes, "Hume does say that it is conceivable that there could be testimony for a miraculous event that is so unlikely to be false that it would be a 'greater miracle' for the testimony to be false than the occurrence of the event. Presumably, he means that, in principle, the likelihood of the provision of particular testimony T, given the non-occurrence of the Miracle M, P(T |~M & K),might be so low that it outweighs the prior improbability of the miracle, P(M | K), making the occurrence of the miracle given the particular testimony and background knowledge, P(M | T & K), greater, perhaps very slightly greater, than .5."
Here Parsons is speaking of something more than the low-grade sociological "miracle" of what Kuhn famously termed a "scientific revolution" – that is, having to replace a previously highly esteemed scientific paradigm with a new one because the old one has been falsified or discredited. (After all, if falsification of an empirically successful scientific theory is a miracle, the history of science furnishes us with miracles almost routinely.) "What I am considering here," he says, "is something different, namely, whether we can witness an event thought to be physically impossible, and still reasonably regard it as physically impossible after its occurrence." In other words, an empirically confirmed miracle is one which science not only cannot explain in principle but furthermore could not explain even if it did occur.
As an example of the latter he offers the account of Elijah at Mt. Carmel facing the false prophets of Baal, where in answer to his prayer (but not his opponents' prayers) fire came down out of the sky and consumed the sacrificial offering of a bull carcass (see 1 Kings 18:20-39). Were such a scenario to be played out before a crowd of skeptical spectators like himself, James Randi, and others, presumably they would be happy to immediately convert. "Do something like that," Parsons says, "and I will be sitting on the front pew of the church of my choice next Sunday." Having witnessed a bona fide miracle, he seems to imply, rationally-minded skeptics would not hesitate to follow the example of the witnesses of Elijah's miracle, that is, fall on their faces and cry out, "The Lord, He is God! The Lord, He is God!" (v. 39).
Now the question I have is this: Given that the antecedent probability of such a miracle taking place is exceedingly low (relative to more mundane alternative explanations), as Parsons maintains, is it really any more antecedently probable that he, Randi and other noted skeptics would simply abandon their scientific-naturalistic commitments and give themselves to the humble service and worship of God upon seeing one? (If not, we have reason to think that the prior probability that skeptics bring to the question of miracles is artificially low. That is, because the evidence is always deemed insufficient to confirm the miracle, the miracle is never confirmed. And because miracles are never confirmed, their prior probability among skeptics will always remain exceedingly low. Thus the evidence is never permitted to accumulate and "build a case" for miracles, because all evidence is summarily dismissed literally prior to examining it objectively.) I think it very likely that rather than suddenly embrace faith, Parsons and company would come up with reasons to retain their skepticism. A column of fire consuming the carcass of a bull following the utterance of a prophet's prayer would be a decidedly unusual and seemingly religiously significant event, to be sure, but recognizing this would only mean there are current "gaps" in our knowledge of such events. To just call it a "miracle" and be done with it would be downright unscientific, after all. So we are told, indeed, concerning the origin of the universe, the origin of life, the resurrection of Jesus, countless well-documented reports of healings, and any other potential or purported miracle one could name.
The way I see it, therefore, such a scenario would involve not one but two miracles – the supernatural consumption of the offering by fire, and the subsequent willing conversion of men whose basic psychological orientations, reputations and careers would most likely be wrecked as a result. C.S. Lewis opened his book Miracles by remarking that the only person he knew who claimed to have seen a ghost, so to speak, actually claimed more precisely to have seen something which appeared just like a ghost ought to appear if ghosts actually existed, but not a ghost per se – since ghosts don't actually exist. "She said that what she saw must have been an illusion or a trick of the nerves."  Lewis concluded that "Seeing is not believing," and then went on to demonstrate why what we believe predetermines to a surprising degree what we see and experience. For a skeptic to believe, then, would be another bona fide miracle. As Jesus once said to a couple of blind men, "According to your faith let it be to you" (Matt. 9:29).
 Keith Parsons, "The Empirical Confirmation of Miracle Claims," Secular Outpost, http://www.patheos.com/blogs/secularoutpost/2016/12/12/empirical-confirmation-miracle-claims/
 Parsons accordingly challenges apologists to conduct the same "experiment" as Elijah. But there's an important difference between these two scenarios: The prophets of Baal put their own sacrifice on the altar and called out to their gods. That is, they were willing to undergo a similar risk as Elijah. If Parsons were to design an experiment pitting Christianity against some other world view, say naturalism, with a commensurate risk of falsification for each, apologists like me might be more inclined to oblige.
 C.S. Lewis, Miracles: A Preliminary Study (New York: HarperCollins, 1996). Originally published 1947.