Miracles - C. S. Lewis [51]
Probabilities of the kind that Hume is concerned with hold inside the framework of an assumed Uniformity of Nature. When the question of miracles is raised we are asking about the validity or perfection of the frame itself. No study of probabilities inside a given frame can ever tell us how probable it is that the frame itself can be violated. Granted a school timetable with French on Tuesday morning at ten o’clock, it is really probable that Jones, who always skimps his French preparation, will be in trouble next Tuesday, and that he was in trouble on any previous Tuesday. But what does this tell us about the probability of the timetable’s being altered? To find that out you must eavesdrop in the masters’ common-room. It is no use studying the timetable.
If we stick to Hume’s method, far from getting what he hoped (namely, the conclusion that all miracles are infinitely improbable) we get a complete deadlock. The only kind of probability he allows holds exclusively within the frame of uniformity. When uniformity is itself in question (and it is in question the moment we ask whether miracles occur) this kind of probability is suspended. And Hume knows no other. By his method, therefore, we cannot say that uniformity is either probable or improbable; and equally we cannot say that miracles are either probable or improbable. We have impounded both uniformity and miracles in a sort of limbo where probability and improbability can never come. This result is equally disastrous for the scientist and the theologian; but along Hume’s lines there is nothing whatever to be done about it.
Our only hope, then, will be to cast about for some quite different kind of Probability. Let us for the moment cease to ask what right we have to believe in the Uniformity of Nature and ask why in fact men do believe in it. I think the belief has three causes, two of which are irrational. In the first place we are creatures of habit. We expect new situations to resemble old ones. It is a tendency which we share with animals; one can see it working, often to very comic results, in our dogs and cats. In the second place, when we plan our actions, we have to leave out of account the theoretical possibility that Nature might not behave as usual tomorrow, because we can do nothing about it. It is not worth bothering about because no action can be taken to meet it. And what we habitually put out of our minds we soon forget. The picture of uniformity thus comes to dominate our minds without rival and we believe it. Both these causes are irrational and would be just as effective in building up a false belief as in building up a true one.
But I am convinced that there is a third cause. ‘In science,’ said the late Sir Arthur Eddington, ‘we sometimes have convictions which we cherish but cannot justify; we are influenced by some innate sense of the fitness of things’. This may sound a perilously subjective and aesthetic criterion; but can one doubt that it is a principal source of our belief in Uniformity? A universe in which unprecedented and unpredictable events were at every moment flung into Nature would not merely be inconvenient to us: it would be profoundly repugnant. We will not accept such a universe on any terms whatever. It is utterly detestable to us. It shocks our ‘sense of the fitness of things’. In advance of experience, in the teeth of many experiences, we are already enlisted on the side of uniformity. For of course science actually proceeds by concentrating not on the regularities of Nature but on her apparent irregularities. It is the apparent