A previious DI post on Lewis and Anscombe
At the same time there is clear and overwhelming evidence that Lewis, at least from fairly early on after the exchange with Anscombe, did not consider his argument refuted. Of course there is the 1960 revision of the relevant chapter, in which he expanded the relevant chapter. It makes no sense to expand the very chapter of one's book which is thought to have been disproved.
But more importantly, Lewis's own response printed in the Socratic Digest later that year showed that he didn't think the argument itself refuted. He wrote:
I admit that valid was a bad for what I meant; veridical (or verific or veriferous) would have been better. I also admit that the cause and effect relation between events and the ground and consequent relation between propositions are distinct. Since English uses the word because for both, let us use Because CE for the cause and effect relation ('This doll always falls on its feet because CE its feet are weighted') and Because GC for the ground and consequent relation ('A equals C because GC they both equal B'). But the sharper this distinction becomes the more my difficulty increases. If an argument is to be verific it must be related to the premises as consequent to ground, i.e. the conclusion is there because GC certain other propositions are true. On the other, our thinking the conclusion is an event that must be related to previous events as effect to cause, i. e. this act of thinking must occur because CE previous events have occurred. It would seem, therefore, that we never think the conclusion because GC it is the consequent of its grounds, but only because CE previous events have happened. If so, it does not seem that the GC sequence makes us more likely to think the true conclusion than not. And this is very much what I mean by the difficulty in Naturalism.
The red-lettered passage suggests that Lewis actually thought that when you draw the Anscombe-type distinctions more sharply, you actually get more trouble for naturalism, not less. Although it would have seemed to the outside observers of the debate that Anscombe helped the naturalist defend naturalism against Lewis's attacks, what Lewis is saying that she did was actually provide ammunition for the case against naturalism.
Lewis also seems to concede some points to Anscombe that I am not sure he really should. For example, valid is a term that has more than one sense. In logic a valid argument is one that is structured in such a way that if the premises are true, the conclusion must be true, but it also can be used to refer to reliability or legitimacy. Anscombe objects to the use of the term irrational causes to refer to non-rational causes, but actually in The Abolition of Man Lewis distinguishes between two senses of irrational; he writes: "It is irrational not as a paralogism is irrational, but as a physical event is irrational." In a previous post I looked up a dictionary and found that Lewis could not be faulted by the way he used "irrational" in the first edition.
The philosophical upshot of the exchange with Anscombe, as Lewis saw it, was that the argument surely needed some cleaning up, but after that cleaning up the argument was, if anything, in better shape than it was before Anscombe criticized it. Given all this, it is amazing to me that Lewis would have given so many signals to other people suggesting that this exchange was some kind of huge defeat for him. I have a distinct impression that there are parts of this story that are below the surface, maybe that we will never fully understand.
I have created a link to a search of my blog for "Anscombe," so that you can see my reflections on that controversy that I have put up here. See also the discussion by Ed Cook on the exchange.