C.S. Lewis’s Dangerous Idea: In Defense of the Argument from Reason, is a relatively short, but philosophically rigorous book. The fundamental burden of the book is to explicate Lewis’s argument found in his Miracles, sometime called the argument from reason, and defend it against some contemporary trends in philosophy. Reppert takes an almost deceptively simple argument against naturalism and reveals it as the powerful apologetic tool that it is.
Lewis’s fundamental claim is that rational inference cannot be explained in purely naturalistic terms, and because it is obvious that rational inference does occur, that is a reason to reject naturalism. The title of the book is a self-confessed spin-off of Dennett’s book, Darwin’s Dangerous Idea. The deliberate connection in the title juxtaposes Dennett’s contention about the fundamental realities of reasoning and Lewis’s. Dennett argued that the best way to build knowledge was through the use of “cranes” and not “skyhooks.” Cranes are ideas and theories built on previous, naturalistically achieved, theories. A skyhook is a derogatory term for theories explained in terms of the supernatural or non-natural, and which, as the title implies, have no real grounding. Lewis’s contention is that there is something fundamental about the way reason works that turns Dennett’s idea on its head.
The first obstacle Reppert works to overcome is what he calls a biographical objection. He notes that many of the objections to Lewis’s philosophy are attacks on Lewis the person and not on his ideas. As legend has it, this argument of Lewis’s was once attacked and (apparently) trounced at a meeting by Elizabeth Anscombe. As the legend goes, Lewis basically gave up his apologetic writings after this apparent embarrassment. But as Reppert details, Lewis not only replied to Anscombe’s objections in an updated version of Miracles, Anscombe openly admitted that the second version was much more rigorous and harder to critique.
This section of the book was helpful to me in that I think many people’s objection to Lewis as a serious philosopher are biographical and not technical. His reputation as a favorite of evangelicals and as the author of children’s books has colored the view of many. In all honesty, I don’t see the need for the seeming bifurcation between serious thinker, religious thinker, and popular author. I think we need more serious and rigorous thinkers, not less, writing popular books than we might have now.
After a helpful chapter on apologetic arguments in which Reppert classifies Lewis as a “critical rationalist,” the philosophical defense begins in ernest. The first objections he deals with are the original objections posited by Anscombe. She critiqued Lewis’s original formulation by arguing that non-rational reasons may give rise to rational inference (Lewis originally used the term “irrational”), and that paradigm cases of reasoning may serve as an example of good and bad rational inference. Later in the book, Reppert continues to defend the argument from reason against more contemporary objectors. He deals with critiques concerning the explanatory power of non-physical causes, and what he calls the inadequacy objection.
Essentially, the inadequacy objection is that when naturalistic/materialistic reasons are found for any explanatory gap, they are the best and most sufficient explanations for phenomena. So, non-physical explanations, by their very nature, fall short. This chapter, along with its specific intent, provides a solid philosophical look into an answer to the “god-of-the-gaps” objection to theism.
Theism, and all the science and philosophy surrounding it, is often rejected as a point of view that will naturally be discarded when a better, materialistic, explanation is discovered. So is the case in this book with rational inference. Lewis and Reppert argue that it cannot be explained by naturalism, and thus is a reason to reject it. Naturalists reply that the non-natural explanation is a stopgap measure that will simply fade away when science has caught up with itself: we used to explain thunder as God doing something or other in the heavens, and now we know differently. It is, so the argument goes, the same with rational inference.
But Reppert’s point is that the argument from reason is no “god-of-the-gaps” argument. Instead of being an argument simply from an ignorance of natural explanation, it is a positive argument about the only good philosophical explanation for rational inference. In other words, if the argument from reason holds, there is logically no naturalistic explanation for the exercise of reason.
This same point can be made in the case of Intelligent Design, and recent work in the area of testable models of nature that infer (or abduct, if “abduct” is a verb) the existence of an intelligence. The straw man argument against ID is the claim that it is a “god-of-the-gaps” point of view that will disappear with the next scientific advancement. But that misses the point entirely. The point is the same as Reppert’s-if the argument holds, naturalism will never explain our origins or our apparent design.
I would highly recommend this book with one simple caveat: be prepared to think. It was a more philosophically rigorous book than I expected. I refuse to call this caveat a warning: it is a challenge and an encouragement to think a bit more deeply about Lewis, about apologetics, and about how your mental faculties work.