Franklin Mason, on my old blog, wrote:
The definition of a miracle that I have in mind is this: event M is miraculous just if (i) M was brought about by an agency outside nature, and (ii) at the time and place at which event M occurred, there was no natural cause at work sufficient to bring about M. This of course leaves open the possibility that M is not at all out of the ordinary. God might, for instance, make a wave a few inches taller than it otherwise would have been so that He might submerge a boat; no observer would ever guess that a miracle had occurred. Though it is not detectable, it is still miraculous. The available energy in the system before God intervened would not have been sufficient to raise the wave to the level that in fact it reached. But M might also be quite spectacular. God might bring about a great conflagration where there had been no material to burn before. How would he do this? Ex nihilo creation of tinder and a spark.
This is clear, interesting, and not obviously mistaken. But here are some comments and criticisms.
Another way to think of nature is to think of it as the sum-total of created entities with the possible exception of abstracta. "Supernatural' will have different meanings depending on how we understand 'nature.' Here are two possible definitions.
D1. X is supernatural =df X is not part of the system of space-time-matter.
D2. X is supernatural =df X is neither a created entity nor an abstractum.
2. Suppose God intervenes in the space-time system causing some unremarkable event to occur: He causes a wave to crest a few inches higher than it would have crested without divine intervention. Franklin thinks this would count as a miracle but I demur. Why should having a supernatural cause or part-cause be sufficient for an event's being miraculous? It may be necessary but why should it be sufficient? According to David Hume in his seminal discussion of miracles in the Inquiry, "A miracle is a violation of the laws of nature. . . ." But laws of nature relate distinct event-types. They assert a "constant conjunction" of such types. Thus, all C-type events are contiguously followed by E-type events. Coulomb's Law, for example, states that all like charged particles repel and all unlike charged particules attract. Since a miracle is a violation of a law of nature, a miracle is not constituted a miracle simply by its extraordinary mode of causation; it must also be an event the type of which does not fit the hitherto observed pattern in nature.
Franklin's high cresting wave is not miraculous despite its divine causation because it does not contravene any hitherto observed regularity or pattern of property-instantiations. If everything supernaturally caused were miraculous, then the physical universe as a whole would be miraculous. But the universe violates no law of nature; it is rather the precondition of laws of nature. How could the exstence of nature violate the laws of nature?
3. It is not easy to understand how God could add causal input to the space-time system. I am not assuming that the system is causally closed. To assume that would be to beg the question against the possibility of miracles. If the question were: How are miracles possible in a causally closed universe? the answer would be easy: They are not possible. So if miracles are possible, the the universe cannot be causally closed. But the question remains how to render this intelligible to ourselves.
Suppose the universe is deterministic. Determinism is the thesis that past states of the universe in conjunction with the laws of nature render only one present state of the universe physically or nomologically possible. Thus if a ten foot wave capsizes a boat, that ten foot wave is necessitated by the past plus the laws. Equivalently, the past plus the laws is sufficient for the occurrence of the ten foot wave. How then can any free act of divine intervention play any role in the causation of the wave? God is of course an agent-cause not an event-cause. And God is libertarianly free. If he intervenes in nature at time t, then he might have done otherwise at t. But since the occurrence of the wave is necessitated by the past plus the laws, God has no role to play except his general role of sustaining the universe and all that is in it from moment to moment.
I end today's meditation with a question: Does the possibility of miracles require that the physical universe be indeterministic?