(This is the next installment of the chapter I'm working....)
Ultimately, C. S. Lewis was a professor of literature and therefore in the humanities and not the sciences. Most of his arguments for faith take place in philosophy or the arts. Yet, this may be a strength because many arguments against Christian faith are presented by scientists as scientific, but are really philosophical in character.
We come then to a confusion—or maybe the shell game—that exists, as well as a nexus for misunderstanding. Science commits itself to methodological naturalism quite rightly. Science, at its core, looks for the interactions, interrelations, and thus cause and effect in the natural world. It does not ask the question, “What is the boiling point of water?” Science keeps testing, hypothesizing, testing, and hypothesizing, until the conclusion is made that, when water at sea level is heated to 100 Celsius, it begins to boil. No god or spirit is needed for that specific phenomenon of nature (other than that a Creator God who put together nature itself, by I will return to that theme below).
The issue is when this method of looking for natural causes elides into philosophical naturalism—that all there exists is nature. Just because science cannot test or number something does not mean it does not exist. It is here—not as a field of study, but as an understanding of the world or sense-of-life, where science often intersects--or even collides with--theology. Many evolutionists see a mindless, “pitiless indifference” (to quote Richard Dawkins) against the entirely purposeful creation by the hand of God. “Everything that can be counted does not necessarily count; everything that counts cannot necessarily be counted,” as Albert Einstein once quipped. Though many scientists, and atheistic philosophers, link methodological naturalism with philosophical atheism, there is no sound reason to do so.
At this point, it might be worthwhile to delineate the difference between theology, which is the study of God, and science, which is the study of the natural world based on the distinction between primary and secondary causation. God is the primary cause—God undergirds and establishes all being. As the great medieval philosopher Thomas Aquinas taught, the nature of God as Creator is that being is always flowing from God. That fact defines primary causation. God is the Cause that undergirds all other causes. Secondary causation is what human beings, and all other agents in the natural world, are given to do. Shakespeare created Hamlet and Ophelia—that is the nature of authorship. They would not exist without him, but within the story they have real interaction. The analogy is not perfect because once the book is written, the real interactions between Hamlet and Ophelia are fixed in a way that ours is not. Nonetheless the central point of the analogy lies here: if Shakespeare were to have stopped writing Hamlet in the midst of its creation, the entire story would have ceased. And so too it is with God. God is the primary cause, but we are the real secondary causes. If God were to stop creating, we would no longer exist.
Returning to our text at hand: “Is Theology Poetry?” is a fascinating lecture—as Lewis is wont to create—not on science per se, or even strictly evolutionary science, but on the use of evolution to create a worldview, one that challenges orthodox Christian accounts of the world. To repeat: This atheistic challenge confuses methodological naturalism (tbe basis of evolution) with philosophical naturalism. Or, in this essay, Lewis juxtaposes science and the Scientific Outlook. Therefore, when scientists grasp this distinction, no conflict between science and God need arise prematurely. Now there may be discoveries about creation and raise questions about the Creator, but science by its nature does not have the power and right to say that all that exists is what it studies. It is as if sculptors were to assert that painting does not exist because they have never touched paint.
Therefore, Lewis held out great hope for science and faith. As he puts in the mouth of the devil, Screwtape, in the first letter of the Screwtape Letters, the imagined correspondence between a senior devil and a junior devil, Wormwood, on how to tempt a human soul.
Above all, do not attempt to use science (I mean, the real sciences) as a defense against Christianity. They will positively encourage him to think about realities he can't touch and see. There have been sad cases among the modern physicists (Letter One).