As far as the practice of science is concerned, is there a practical difference between assuming the probability that a miracle will not occur is 1.00 and assuming the probability that a miracle will not occur is 0.9999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999?
Tom Gilson addresses this question in his contribution to Naturalism and Its Alternatives in Scientific Methodologies in a chapter entitled Methodological Naturalism, Methodological Theism, and Regularism.
Gilson starts off by quoting J. B. S. Haldane:
My practice as a scientist is atheistic. That is to say, when I set up an experiment I assume that no god, angel or devil is going to interfere with its course; and this assumption has been justified by such success as I have achieved in my professional career. I should therefore be intellectually dishonest if I were not also atheistic in the affairs of the world.
Notice Haldane’s false dichotomy: We must either assume supernatural events never occur, or we must assume some supernatural agent might fiddle with every one of our experiments. And if we assume the latter science – the study of natural regularities – is impossible.
Haldane’s dichotomy is false, because, as Gilson notes, there is a third option: “that God established the natural order to work regularly almost all of the time but with extremely rare exceptions.” If this is the case (and it is according to Christian doctrine), as a practical matter, there is no need to insert the metaphysical biases of either theism or naturalism into scientific methodology.
Why should we care if “naturalism” is inserted into the picture so long as it is of the “methodological” variety (assumed to be true for a limited purpose) as opposed to the ontological variety (asserted to be actually true)? The answer is, as Haldane’s quote demonstrates, assuming a methodological naturalism inevitably leads down the slippery slope at the bottom of which is the unwarranted conclusion that science supports ontological naturalism. It does not, but many people mistakenly believe that it does.
Gilson proposes “regularism” (“the methodological expectation of reliable regularity of cause and effect in nature”) as a metaphysically neutral alternative to methodological naturalism:
All that science requires is that nature operate regularly. That’s all methodological naturalism provides, conceptually, for science. Science does not require favoring one metaphysical viewpoint over another, provided that both are sufficiently orderly and regular . . . So I conclude here by proposing we drop all the “methodological” business— all the metaphysical trappings, too— and realize that science operates like all of life on an expectation of natural regularity. If we must have an “ism” to describe it, let’s use regularism.
This is an excellent suggestion. The success of science is not based on an assumption of atheism, as Haldane mistakenly believed. It is based on the Christian idea that God established an orderly universe with natural regularities. Science assumes regularity. As a practical matter it matters not one whit why that regularity obtains.
As Chesterton wrote in “The Ethics of Elfland”:
We risk the remote possibility of a miracle as we do that of a poisoned pancake or a world-destroying comet. We leave it out of account, not because it is a miracle, and therefore an impossibility, but because it is a miracle, and therefore an exception.