Miracles - C. S. Lewis [9]
But if they did they are all invalid inferences. Such a process will no doubt produce expectation. It will train men to expect fire when they see smoke in just the same way as it trained them to expect that all swans would be white (until they saw a black one) or that water would always boil at 212° (until someone tried a picnic on a mountain). Such expectations are not inferences and need not be true. The assumption that things which have been conjoined in the past will always be conjoined in the future is the guiding principle not of rational but of animal behaviour. Reason comes in precisely when you make the inference ‘Since always conjoined, therefore probably connected’ and go on to attempt the discovery of the connection. When you have discovered what smoke is you may then be able to replace the mere expectation of fire by a genuine inference. Till this is done reason recognises the expectation as a mere expectation. Where this does not need to be done—that is, where the inference depends on an axiom—we do not appeal to past experience at all. My belief that things which are equal to the same thing are equal to one another is not at all based on the fact that I have never caught them behaving otherwise. I see that it ‘must’ be so. That some people nowadays call axioms tautologies seems to me irrelevant. It is by means of such ‘tautologies’ that we advance from knowing less to knowing more. And to call them tautologies is another way of saying that they are completely and certainly known. To see fully that A implies B does (once you have seen it) involve the admission that the assertion of A and the assertion of B are at bottom in the same assertion. The degree to which any true proportion is a tautology depends on the degree of your insight into it. 9 × 7 = 63 is a tautology to the perfect arithmetician, but not to the child learning its tables nor to the primitive calculator who reached it, perhaps, by adding seven nines together. If Nature is a totally interlocked system, then every true statement about her (e.g. there was a hot summer in 1959) would be a tautology to an intelligence that could grasp that system in its entirety. ‘God is love’ may be a tautology to the seraphim; not to men.
‘But’, it will be said, ‘it is incontestable that we do in fact reach truths by inferences’. Certainly. The Naturalist and I both admit this. We could not discuss anything unless we did. The difference I am submitting is that he gives, and I do not, a history of the evolution of reason which is inconsistent with the claims that he and I both have to make for inference as we actually practise it. For his history is, and from the nature of the case can only be, an account, in Cause and Effect terms, of how people came to think the way they do. And this of course leaves in the air the quite different question of how they could possibly be justified in so thinking. This imposes on him the very embarrassing task of trying to show how the evolutionary product which he has described could also be a power of ‘seeing’ truths.
But the very attempt is absurd. This is best seen if we consider the humblest and almost the most despairing form in which it could be made. The Naturalist might say, ‘Well, perhaps we cannot exactly see—not yet—how natural selection would turn sub-rational mental behaviour into inferences that reach truth. But we are certain that this in fact has happened. For natural selection is bound to preserve and increase useful behaviour. And we also find that our habits of inference are in fact useful. And if they are useful they must reach truth’. But notice what we are doing. Inference itself is on trial: that is, the Naturalist has given an account of what we thought to be our inferences which suggests that they are not real insights at all. We, and he,