The “grand” encounter which came to be known as the Lewis-Anscombe Debate flew in on the wings of a discussion that Lewis had involved himself in with Professor Rice. A discussion in which Lewis had responded to a paper Professor Rice had authored titled, The Grounds of Modern Agnosticism. This event generated so much controversy at the time that I thought it might be worth our while to give it some consideration since there have been much misleading information on it. To do this I have decided to post the two versions of the chapter III from Lewis’ book titled Miracles, from which the controversy grew. 
At the bottom you will find a You Tube and a couple of blogs that might be of interest to those who want to consider this discussion more fully.
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To access the chapter before Lewis amended it click here: ==> The Self Contradiction of the Naturalist which came out of a 1946 edition of Miracles. To access a PDF copy from a 1960 edition of the chapter-after it being rewritten- click here: ==> The Cardinal Difficulty of Naturalism.
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Walter Hooper, the editor of a compilation of Lewis’ writings, put out under the title of God In The Dock, tells us at the end of the chapter Religion Without Dogma, one of Lewis’ responses to Professor Price’s paper that: [Note: The debate between Lewis and Professor Price did not end here. In The Socratic Digest, No. 4 [1948], there followed a ‘Reply’ to Lewis’ Religion Without Dogma?” by Professor Price (pp. 94-102). Then at a meeting of the Socratic Club on 2nd February 1948, Miss G. E. M. Anscombe read a paper entitled, “ A Reply to Mr. C.S. Lewis’ argument that “Naturalism is Self-refuting”’, afterwards published in that same issue of the digest (p. 7-15) as Professor Prices’ ‘Reply’. Miss Anscombe criticized the argument found on pp. 136-8 of the paper printed above as well as chapter III , ‘The Self-Contradiction of the Naturalists” of Lewis’ book Miracles London (1927). The two short pieces that follow are (A) the Socratic minute-book account of Lewis’ reply to Miss Anscombe and (B) a reply written by Lewis himself—both reprinted from the same issue from the digest mentioned above (p. 15-16). Aware that the third chapter of Miracles was ambiguous, Lewis revised this chapter for the Fontana (1960) issue of Miracles in which chapter III is retitled ‘The Cardinal Difficulty of Naturalism’].
A
In his reply Mr. C.S. Lewis agreed that the words ‘cause’ and ‘ground’ were far from synonymous but said that the recognition of a ground could be the cause of assent, and that assent was only rational when such was its cause. He denied that such words as ‘recognition’ and perception’ could be properly used of a mental act among whose causes the thing perceived or recognized was not one. Miss Anscombe said that Mr. Lewis had misunderstood her and thus the first part of the discussion was confined to the two speakers who attempted to clarify their positions and their differences. Miss Anscombe said that Mr. Lewis was still not distinguishing between ‘having reasons’ and ‘having reasoned” in the causal sense, Mr. Lewis understood the speaker to be a techtrachotomy thus: (1) logical reasons; (2) having reasons (i.e. psychological); (3) historical causes; (4) scientific causes or observed regularities. The main point in his reply was that an observed regularity was only the symptom of a cause, and not the cause itself, and in reply to an interruption by the Secretary he referred to his notion of cause as ‘magical’. An open discussion followed, in which some members tried to show Miss Anscombe that there was a connection between ground and cause, while others contended against the President (Lewis) that the test for validity of reason never in any event be such a thing as the state of the blood stream. The President finally admitted that the word ‘valid’ was an unfortunate one. From the discussion in general it appeared that Mr. Lewis would have to turn his argument into a rigorous analytic one, if his notion of ‘validity’ as the effect of causes were to stand the test of the questions to him.
B
I admit valid was a bad word 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 of both, let us here 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 become verific the conclusion must be related to the premises as consequent to ground i.e. the conclusion the premises are there because GC certain other propositions are true. On the other hand, our thinking the conclusion is an event and must be related to the 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 certain 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 meant by the difficulty in Naturalism. God In The Dock, pages 146-7.
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I thought you might find this rather interesting, although very cerebral, presentation of the debate by a university mathematics professor, a Dr. Russell Howard, on some of the not so obvious philosophical elements that come into play with a discussion of this kind. I hope you enjoy it.
Russell Howell on “The Lewis-Anscombe Debate: Milieu, Mutations, and Mathematics”
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A Web Page
==> Soliloquium <==
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==> a dangerous idea <==
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Click ==> C.S. Lewis’s Argument against Naturalism, part 6 <== Click