An appeal to the miraculous has had a role in theistic treatments of the afterlife as well as in arguments for the existence of God (the appeal to miracles has been used to provide evidence of revelation or incarnation). Let us consider first the concept of a miracle and then some of the challenges of assessing reports of the miraculous.

In the eighteenth century, David Hume defined a miracle as a violation of the laws of nature brought about by a supernatural agent. This has been used by some theists, but it has also been criticized as failing to capture the religious significance of the miraculous. Not just any event that is caused by a supernatural agent would be considered a miracle. For this reason, contemporary defenders of an argument from miracles usually work toward a concept of the miraculous which does blend into more general considerations of religious experience but also does not become a merely mechanical, quasi-scientific notion.

To this end, a miracle may be defined here as an event brought about by God for a holy or divine purpose, an event that differs from God’s general creative activity of sustaining the world and its laws regulating organic decomposition and regeneration. On this view, such normal regeneration would not count as a miracle, but God’s causing an extraordinary event that differs from this regularity would do so. Grace Jantzen describes how this concept would work:

If a situation arose in which there were compelling evidence for believing that Jesus rose from the dead, a revision of our supposed natural laws would hardly be the appropriate response.… Where there is a single exception to a perfectly well established and well understood law, and one that is inexplicable unless one appeals to divine intervention (in which case it assumes enormous significance), what can be gained by making the nomological read, “All men are mortal except those who have an unknown quality, observed on only one occasion and hitherto accountable for only by divine intervention.”… The skeptical response would be inadequate. (Jantzen 1979, 325)

The theistic argument from miracles thereby works with concepts of agency and evidence, raising the question of when reported observations give us reason to believe that a good purposive agent is responsible for some event.

The best-known critic of the argument from miracles is David Hume. Hume’s chief objection rests on a concept of intellectual responsibility:

A wise man, therefore, proportions his belief to the evidence. In such conclusions as are founded on an infallible experience, he expects the event with the last degree of assurance, and regards his past experience as a full proof of the future existence of that event. In other cases, he proceeds with more caution: He weighs the opposite experiments: He considers which side is supported by the greater number of experiments: to that side he inclines, with doubt and hesitation; and when at last he has fixed his judgment, the evidence exceeds not what we properly call probability. All probability, then, supposes an opposition of experiments and observations, where one side is found to overbalance the other, and to produce a degree of evidence, proportioned to the superiority. A hundred instances or experiments on one side, and fifty on another, afford a doubtful expectation of any event; though a hundred uniform experiments, with only one that is contradictory, reasonably begets a pretty strong degree of assurance. In all cases, we must balance the opposite experiments, where they are opposite, and deduct the smaller number from the greater, in order to know the exact force of the superior evidence. (Hume 1902, section X, part 1)

And Hume therefore concludes that “the proof against a miracle…is as entire as any arguments from experience can possibly be imagined.” His objection has been further defended by Antony Flew, J. L. Mackie, and others.

The most widespread theistic response to this objection has been to question whether Hume has simply begged the question. If one assumes at the outset that there have never been exceptions to the laws of nature, then one has assumed from the beginning that there have never been any miracles. It is not clear, however, whether Hume does beg the question in this fashion. Arguably, the strength of Hume’s position is that he highlights the great weight of testimony on behalf of the laws of nature and the comparatively more slender testimony on behalf of exceptions to these laws. J. L. Mackie articulates this Humean strategy as follows:

It is…not enough for the defender of a miracle to cast doubt (as well he might) on the certainty of our knowledge of the law of nature that seems to have been violated. For he must himself say that this is a law of nature: otherwise the reported event will not be miraculous. That is, he must in effect concede to Hume that the antecedent improbability of this event is as high as it could be, hence that, apart from the testimony, we have the strongest possible grounds for believing that the alleged event did not occur. This event must, by the miracle advocate’s own admission, be contrary to the genuine, more merely a supposed law of nature, and therefore maximally improbable. It is this maximal improbability that the weight of the testimony would have to overcome. (Mackie 1983, 25)

If Mackie is right, an argument for theism based on the appeal to miracles will always be at a disadvantage.

A second theistic reply is to challenge the use of probability employed by Mackie and other Humeans. Stephen Evans points out how Humean arguments presuppose a substantial background of philosophical commitments:

The defender of miracles may claim that whether miracles occur depends largely on whether God exists, what kind of God he is, and what purposes he has. Given enough knowledge of God and his purposes in relation to human history, occurrence of a miracle might be in some situations highly probable, or at least not nearly so improbable as Hume suggests.… In absence of any firm knowledge about God and his purposes, it would still be rash to claim with Hume that the probability of a miracle is vanishingly small. Rather it would appear more reasonable to conclude that it is hard, if not impossible, to estimate the a priori probability of a miracle; and therefore one should try to look at the evidence for miracles with a somewhat open, though cautiously skeptical, mind. (Evans 1985, 113)

Evans and other theists such as Alvin Plantinga thereby place the debate about the miraculous in the context of an overriding debate between theism and naturalism.

Does this latter strategy completely undermine any evidential role for an argument from miracles? Not necessarily, for the argument can be seen as part of a broader, cumulative case for theism. The data advanced on behalf of theism might well be broadened to include not just religious experience, the contingency of the cosmos, and so on, but also certain accounts of what appears to be specific divine activity. The final outcome may resemble the argument for theism based on religious experience that was discussed in chapter three.

An appeal to miracles has sometimes been challenged on the grounds that miracle narratives seem to support competing religious traditions. This raises the general question about how the different world religions should be considered in relationship to one another and to truth. This is also relevant to the problem of evil. Is there more than one valid, religious path to enlightenment or salvation? Or, do different religions set up exclusive alternatives?