In his book, Missionaries to the skeptics (Mercer University Press, 1995, p. 47 John A. Sims says, “Naturalism makes a modest claim. It claims that all know facts support the view that the whole of reality emerged from and is dependent upon material nature.” If this is the case, there is not need to have anything or anyone beyond the physical world explain anything: it just “happened.” We originated in nature and any appeal to supernatural means is discarded.

Lewis questions this and in his book Miracles: A preliminary study (Geoffrey Bles, 1947), he states “…the question whether miracles occur can never be answered simply by experience” (11)….This book is intended as a preliminary to historical inquiry…Those who assume that miracles cannot happen are merely wasting their time by looking into the texts: we know in advance what results they will find for they have begun by begging the question” (13). In other words, the first choice a person must make is between Naturalism and Supernaturalism because “[if] Naturalism is true, every finite thing or event must be (in principle) explicable in terms of the Total System” (13).

By Naturalism Lewis means “the doctrine that only Nature—the whole interlocked system—exists” (13) and that it does not exist by its own accord. Lewis believes strongly that we can reason and that “no thought is valid if it can be fully explained as the result of irrational causes” (17, his italics). Furthermore “You have to assume that inference is valid before you can even begin your argument for its validity” (29). Rational thought is therefore interlocked with “the great interlocking system of irrational events which we call Nature” although “Nature is quite powerless to produce Rational thought” (33).

Lewis further believes it is absurd to think that “Nature produced God” or even the human mind—the two go together (41). And because reasoning matters—it is from God—it cannot be denied by the Naturalist “without (philosophically speaking) cutting his own throat” (43). Further, “A naturalistic Christianity leaves out all that is specifically Christian” (83).

How could Nature, created by a good God come to its present deplorable condition? According to Christians, this is due to sin because “Nature has all the air of a good thing spoiled” (147). That is, “Spirit and Nature have quarreled in us; that is our disease” (190) and only God’s redemptive gift can heal us.

Victor Reppert examines Lewis’s views of naturalism in volume 3, chapter 7 of Bruce Edward’s four volume study (Praeger, 2007) of the life and works of Lewis. His chapter, “Miracles: C.S. Lewis’s critique of naturalism” conclude with this thought: “A naturalistic view of the universe, according to which there is nothing in existence that is not in a particular time and a particular place, hard pressed to reconcile their theory of the world with the idea that we as humans can access not only what is, but also what must be” (177). It follows that the maker of the universe is a rational being—whom Christians call God—and that “the argument from reason is unrefuted and constitutes a substantial reason for preferring a theistic understanding of the universe to a naturalistic one” (178).

Reppert had already examined what he called C.S. Lewis’s dangerous idea (the title of his book, InterVarsity Press, 2003). The idea, as given in the subtitle of the books was “In defense of the argument from reason,” which was Lewis’s attempt to show that you could not “account for the activity of reasoning as a byproduct of a fundamentally nonpurposive system,” without reason (8). Reppert also examines the famous argument put forth by Elizabeth Anscombe against Lewis in his book on miracles. He allows that her objections “rightfully lead us to recognize the distinction between irrational and nonrational causes” (70).

Reppert further updates his arguments on Lewis’s arguments from reason in a chapter called “Defending the dangerous idea,” in C.S. Lewis as philosopher: truth, goodness and beauty, edited by David Battett, Gary R. Habermas and Jerry L. Walls (IVP Academic, 2008, pp. 53-67). He concludes that “A naturalistic view of the universe, in which there nothing in existence that is not a particular time and a particular place, is hard-pressed to reconcile with the fact that some truths that we know are not only true in this world, but also in all possible worlds” (67).

The Cambridge Companion to C.S. Lewis, edited by Robert MacSwain and Michael Ward (Cambridge University Press, 2010) has a chapter (8) called “On naturalism” by Charles Taliaferro. He reviews Lewis’s arguments against naturalism: arguments from reason, morality and life and death and concludes that “Lewis deserves a rightful place in considering arguments pro and con, not only because of the merits of his own arguments, but because he offers us a valuable lesson in assessing any theory” (125). Lewis uses both reason and imagination to appreciate the natural world while enhancing his view of the supernatural.

As David C. Downing points out in Mysticism in C.S. Lewis: Into the region of the awe (InterVarsity Press, 205, p. 45), “In Mere Christianity Lewis goes beyond momentary impressions and gives an account of everything in the cosmos as a mirror of God’s nature.” To Lewis there was joy anda gratitude for the beauty that lay beyond the natural world.

J.T. Sellars provides a definitive picture on how Lewis combined imagination with and understanding in his book Reasoning beyond reason: Imagination as a theological source in the work of C.S. Lewis (Pickwick publications, 2011). Some things that I noted that are relevant to Lewis and naturalism are:

  • We do not start by doubting reason; we presuppose it (15)
  • The notion of rationality is not independent of God (16) because God is the source from which reasoning power comes
  • Imagination is not falsehood or wishful thinking (45)
  • Rationality resides beyond the step-by-step reason of modernity (51)
  • Our worldview is a representation of reality (61)
  • With Lewis’s Chronicles, everything began with images (74n44)
  • There is a real Good, the true and the beautiful, independent of our particularity and tradition, but mediated through our tradition (107; 118)
  • The poetic and mythic utilize the imagination, a deeper level of consciousness (166)
  • When the spirit and God descend to nature we have difficult understanding the higher (197)
  • Reasoning beyond the rational is present in imagination—the prelude to action and motivation (202)