Alvin Plantinga offers at least two major solutions to the problem of divine action; that physical laws of the Newtonian sort are (often implicitly) qualified to apply only to causally closed systems, and that quantum physics has overtaken Newtonian physics as the fundamental description of the material world. Regarding the first solution, Plantinga states:
According to Newton and classical mechanics, natural laws describe how the world works when, or provided that the world is a closed (isolated) system, subject to no outside causal influence. In classical physics, the great conservation laws deduced from Newton's laws are stated for closed or isolated systems.
These principles, therefore, apply to isolated or closed systems. If so, however, there is nothing in them to prevent God from changing the velocity or direction of a particle. If he did so, obviously, energy would not be conserved in the system in question; but equally obviously, that system would not be closed, in which case the principle of conservation of energy would not apply to it. Indeed, there is nothing here to prevent God from miraculously parting the Red Sea, or bringing someone back to life, or, for that matter, creating ex nihilo a full-grown horse in the middle of Times Square. It is entirely possible for God to create a full-grown horse in the middle of Times Square without violating the principle of conservation of energy. That is because the systems including the horse would not be closed or isolated.
Furthermore, it is no part of Newtonian mechanics or classical science generally to declare that the material universe is a closed system. You won’t find that claim in physics textbooks—naturally enough, because that claim isn’t physics, but a theological or metaphysical add-on. (How could this question of the causal closure of the physical universe be addressed by scientific means?) Classical science, therefore, doesn’t assert or include causal closure. Moreover, the natural laws offer no threat to special divine action. Miracles are often thought to be problematic, in that God, if he were to perform a miracle, would be involved in “breaking,” going contrary to, abrogating, suspending, a natural law. But if God were to perform a miracle, it wouldn’t at all involve contravening a natural law. That is because, obviously, any occasion on which God performs a miracle is an occasion when the universe is not causally closed; and the laws say nothing about what happens when the universe is not causally closed. (Plantinga, Where the Conflict Really Lies, 2011, p. 78-79)
The idea here is that when properly qualified, the laws of physics are of the form "if/when/while the universe is causally closed, P," where the consequent P is, i.e., "nothing can accelerate from a speed less than to a speed greater than light."
Initially this seemed like a well presented solution, but I have since been informed that in science, any system which is not causally closed can never become causally closed again; once energy is added from the outside, its causal influence on the system is chaotic and the system is forever "open." Therefore, it would not make sense to talk about the consequent of some law not applying "when" or "while" the universe is causally closed. Rather, once a miracle occurred, no consequent of a law of classical physics would be applicable to the real world ever again. Of course, if we assess the "if" conditional, and just say the universe is not causally closed, then the consequents don't apply at all. Both implications seem absurd; laws are established for the exact purpose of describing the operation of the material world, and it's fairly clear that they don't suddenly stop applying after the first miracle in history.
Of course, the second solution would remain sound, and sufficient to undercut the problem of divine action, but the implications for the first solution would still be interesting. This objection seems far too easy to have evaded the mind of Plantinga. Why does it fail?