Although C.S. Lewis was a medievalist, among other things, I encountered only The Discarded Image among his writings in the field. He was a scholar of the high and later medieval periods, and I concentrated on the Anglo-Saxon material, so I would have had to pursue him on my own for a fuller familiarity. I'm certain I read The Lion, the Witch, and the Wardrobe when I was a kid. Although I don't remember much of that book itself, I do remember that the fantasy was pretty good.
Lewis is today considered a big deal in Christian evangelical and apologetic circles. A quick glance through notable quotes by Lewis, or a more extended reading through works such as Mere Christianity, reveals why he is held in high esteem by defenders of the faith. He sounds good. He gives a sharp impression of even-handed questioning and reasoning--and of course he comes to the right conclusions that atheism is untenable and that Jesus is God (or isn't not-God).
One brief argument of Lewis's bothers me particularly:
If the solar system was brought about by an accidental collision, then the appearance of organic life on this planet was also an accident, and the whole evolution of Man was an accident too. If so, then all our present thoughts are mere accidents -- the accidental by-product of the movement of atoms. And this holds for the thoughts of the materialists and astronomers as well as for anyone else’s. But if their thoughts -- i.e., of Materialism and Astronomy -- are merely accidental by-products, why should we believe them to be true? I see no reason for believing that one accident should be able to give me a correct account of all the other accidents. It’s like expecting that the accidental shape taken by the splash when you upset a milk-jug should give you a correct account of how the jug was made and why it was upset.This bit comes from "Answers to Questions on Christianity," which can be found in God in the Dock. The main problem is Lewis's unfortunate choice of the word "accident" and its variants--used here an astonishing 9 times in a passage of only 149 words (6%).
Now, "accident" has several senses, including one that invokes chance and the lack of apparent or deliberate cause. So it's a legitimate word for Lewis to use. The unfortunate part is that it's not really accurate in the context of how the solar system was brought about. A more judicious word to use would have been "natural," like so:
If the solar system was brought about by a natural collision, then the appearance of organic life on this planet was also natural, and the whole evolution of Man was natural too. If so, then all our present thoughts are natural -- the natural by-product of the movement of atoms. And this holds for the thoughts of the materialists and astronomers as well as for anyone else’s. But if their thoughts -- i.e., of Materialism and Astronomy -- are merely natural by-products, why should we believe them to be true? I see no reason for believing that one natural by-product should be able to give me a correct account of all the other natural by-products. It’s like expecting that the natural shape taken by the splash when you upset a milk-jug should give you a correct account of how the jug was made and why it was upset.How different Lewis's argument appears with the words substituted! Yes, precisely, the solar system was well within the purview of natural forces in the universe. Yes, the physical parameters of the universe and both the relations and reactions of objects to one another made organic life possible. Yes, the evolution of creatures such as humanity were potential paths allowed by nature. And yes, thinking is natural too.
Lewis really starts to err when he denigrates human thought as being untrustworthy unless it has been given by God. We of course use not only thought but also tools, and tools are artificial--not natural, not accidental. So, even if our thoughts are untrustworthy by themselves--and they are--we have been good enough to develop tools that enhance the depth and breadth of our thought. These tools also augment our abilities to apprehend and understand the universe. From our math and logic to our telecommunications and telescopes, we've been able to grope our way to discriminating reliable from specious thinking.
The milk-splash crack doesn't work either because the shape, positioning, speed, and other factors of a milk splash will provide us lots of information from which to establish hypothesis on the jug's composition and movements.
Obviously, Lewis's apologetic ouvere should not be dismissed on one brief and lousy answer of his. Nevertheless, his answer is quite poor on several levels. It's biased, narrow, and surprisingly unimaginative. Were I a Christian apologist with Lewis's works in my hand, I might invoke the rule of "Fool me once, shame on you; fool me twice, shame on me."