Once again, the great Oxford Don summarizes well difficult theological topics:
God might have arrested this process by miracle: but this - to speak in somewhat irreverent metaphor - would have been to decline the problem which God had set Himself when He created the world, the problem of expressing His goodness through the total drama of a world containing free agents, in spite of, and by means of, their rebellion against Him. The symbol of a drama, a symphony, or a dance, is here useful to correct a certain absurdity which may arise if we talk too much of God planning and creating the world process for good and of that good being frustrated by the free will of the creatures. This may raise the ridiculous idea that the Fall took God by surprise and upset His plan, or else - more ridiculously still - that God planned the whole thing for conditions which, He well knew, were never going to be realised. In fact, of course, God saw the crucifixion in the act of creating the first nebula. The world is a dance in which good, descending from God, is disturbed by evil arising from the creatures, and the resulting conflict is resolved by God's own assumption of the suffering nature which evil produces. The doctrine of the free Fall asserts that the evil which thus makes the fuel or raw material for the second and more complex kind of good is not God's contribution but man's. This does not mean that if man had remained innocent God could not then have contrived an equally splendid symphonic whole - supposing that we insist on asking such questions. But it must always be remembered that when we talk of what might have happened, of contingencies outside the whole actuality, we do not really know what we are talking about. There are no times or places outside the existing universe in which all this 'could happen' or 'could have happened'. I think the most significant way of stating the real freedom of man is to say that if there are other rational species than man, existing in some other part of the actual universe, then it is not necessary to suppose that they also have fallen.
Chapter 5, "The Fall of Man," in The Problem of Pain (1962).