So we could have good reason to believe that a law of nature has been violated. But for a violation of a law of nature to be a miracle, it has to be caused by a god, that is, a very powerful rational being who is not a material object. What could be evidence that it was?

To explain an event as brought about by a rational agent with intentions and purposes is to give an entirely different kind of explanation of its occurrence from an explanation by scientific laws acting on precedent causes. Our normal grounds for attributing an event to the agency of an embodied rational agent A is that we or others perceived A bringing it about or that it is the sort of event that A typically brings about and that A, and no one else of whom we have knowledge, was in a position to bring it about. The second kind of ground is only applicable when we have prior knowledge of the existence of A. In considering evidence for a violation E of a law of nature being due to the agency of a god, I will distinguish two cases, one where we have good reason on grounds other than the occurrence of violations of laws of nature to believe that there exists at least one god, and one where we do not.

Let us take the second case first. Suppose we have no other good reason for believing that a god exists, but an event E then occurs which, our evidence indicates, is a non-repeatable counterinstance to a true law of nature. Now we cannot attribute E t o the agency of a god by seeing the god's body bring E about, for gods do not have bodies. But suppose that E occurs in ways and circumstances C strongly analogous to those in which occur events brought about by human agents, and that other violations occur in such circumstances. We would then be justified in claiming that E and other such violations are, like effects of human actions, brought about by agents, but ones unlike men in not being material objects. This inference would be justified because, if an analogy between effects is strong enough, we are always justified in postulating slight difference in causes to account for slight difference in effects.

Thus if because of its other observable behaviour we say that light is a disturbance in a medium, then the fact that the medium, if it exists, does not, like other media, slow down material bodies passing through it, is not by itself (viz., if there are no other disanalogies) a reason for saying that the light is not a disturbance in a medium, but only for saying that the medium in which light is a disturbance has the peculiar property of not resisting the passage of material bodies. So if, because of very strong similarity between the ways and circumstances of the occurrence of E and other violations of laws of nature to the ways and circumstances in which effects are produced by human agents, we postulate a similar cause-a rational agent, the fact that there are certain disanalogies (viz., we cannot point to the agent, say where his body is) does not mean that our explanation is wrong. It only means that the agent is unlike humans in not having a body. But this move is only justified if the similarities are otherwise strong. Nineteenth-century scientists eventually concluded that for light the similarities were not strong enough to outweigh the dissimilarities and justify postulating the medium with the peculiar property.

Now what similarities in the ways and circumstances C of their occurrence could there be between E (and other violations of laws of nature) and the effects of human actions to justify the postulation of similar causes? Suppose that E occurred in answer to a request. Thus E might be an explosion in my room, totally inexplicable by the laws of nature, when at the time of its occurrence there were in a room on the other side of the corridor men in turbans chanting "O God of the Sikhs, may there be an explosion in Swinburne's room." Suppose, too, that when E occurs a voice, but not the voice of an embodied agent, is heard giving reasonable reasons for granting the request. When the explosion occurs in my room, a voice emanating from no man or animal or man- made machine is heard saying "Your request is granted. He deserves a lesson." Would not all this be good reason for postulating a rational agent other than a material object who brought about E and the other violations, an agent powerful enough to change instantaneously by intervention the properties of things, viz., a god? Clearly if the analogy were strong enough between the ways and circumstances in which violations of laws of nature and effects of human action occur, it would be. If furthermore the prayers which were answered by miracles were prayers for certain kinds of events (e.g., relief of suffering, punishment of ill-doers) and those which were not answered by miracles were for events of different kinds, then this would show something about the character of the god. Normally, of course, the evidence adduced by theists for the occurrence of miracles is not as strong as I have indicated that very strong evidence would be. Violations are often reported as occurring subsequent to prayer for them to occur, and seldom otherwise; but voices giving reason for answering such a request are rare indeed. Whether in cases where voices are not heard but the occurrence of a violation E and of prayer for its occurrence were both well confirmed, we would be justified in concluding that the existence of a god who brought E about is a matter of whether the analogy is strong enough as it stands. The question of exactly when an analogy is strong enough to justify an inference based on it is a difficult one. But my only point here is that if the analogy were strong enough, the inference would be justified.

Suppose now that we have other evidence for the existence of a god. Then if E occurs in the circumstances C, previously described, that E is due to the activity of a god is more adequately substantiated, and the occurrence of E gives further support to the evidence for the existence of a god. But if we already have reason to believe in the existence of a god, the occurrence of E not under circumstances as similar as C to those under which human agents often bring about results, could nevertheless sometimes be justifiably attributed to his activity. Thus, if the occurrence of E is the sort of thing that the only god of whose existence we have evidence would wish to bring about if he has the character suggested by the other evidence for his existence, we can reasonably hold him responsible for the occurrence of E which would otherwise be unexplained. The healing of a faithful blind Christian contrary to the laws of nature could reasonably be attributed to the God of the Christians, if there were other evidence for his existence, whether or not the blind man or other Christians had ever prayed for that result.

For these reasons I conclude that we can have good reason to believe that a violation of a law of nature was caused by a god, and so was a miracle. I would like to make two final points, one to tidy up the argument and the other to meet a further argument put forward by Hume which I have not previously discussed.

Entia non sunt multiplicanda praeter necessitatem. — Unless we have good reason to do so we ought not to postulate the existence of more than one god, but to suppose that the same being answers all prayers. But there could be good reason to postulate the existence of more than one god, and evidence to this effect could be provided by miracles. One way in which this could happen is that prayers for a certain kind of result, for example, shipwreck, which began "O. Neptune" were often answered, and also prayers for a different kind of result, for example, success in love, which began "O. Venus" were also often answered, but prayers for a result of the first kind beginning "O. Venus," and for a result of the second kind beginning "O. Neptune" were never answer ed. Evidence for the existence of one god would in general support, not oppose, evidence for the existence of a second one since, by suggesting that there is one rational being other than those whom we can see, it makes more reasonable the postulation of another one.