He Has Hemmed Us In: Why Reason Requires a Divine Mind

“If a man feels that all the movements of his own mind are meaningless, then his mind is meaningless, and he is meaningless; and it does not mean anything to attempt to discover his meaning. Most fundamental sceptics appear to survive, because they are not consistently sceptical and not at all fundamental.”

~ G.K. Chesterton, St. Thomas Aquinas, 1933[1]

Do you have a favorite apologetics argument? Students often ask me this, and my answer is always an unhesitating “Yes.” It’s a topic I love discussing, especially with those who are new to the field. While it may not present the strongest case overall for the existence of God—a cumulative case is truly the most powerful—it’s certainly the most meaningful one for me personally.

My favorite is the Argument from Reason, an argument most famously articulated by C.S. Lewis in his book Miracles and Alvin Plantinga in his Evolutionary Argument Against Naturalism. This defense focuses on the legitimacy of the reasoning process, essentially authenticating the act of argumentation itself. Its difficulty, however, lies in its proximity. We are so thoroughly steeped in the reasoning process that it is not only easy to overlook, but it also presents us with an unusual paradox the moment we try to look. We cannot step outside the fact that we have to use the very faculty we are investigating to carry out the investigation.

Lewis Versus Plantinga

Although there is overlap between Lewis’s and Plantinga’s formulations—both are concerned with the self-defeating nature of philosophical naturalism—I prefer Lewis’s approach because it digs deeper into the foundations of human rationality, making its consequences more profound. While Plantinga focuses on the unreliability of reasoning if the brain is a product of blind evolution, Lewis examines the validity of logic itself if such reasoning is solely dependent upon non-rational matter.

Furthermore, Lewis argues that if we can genuinely use logic to reach a conclusion, we do not live in a closed physical system as naturalism contends. This breach then opens up the possibility of the miraculous. Though I will move between the two formulations, as they are philosophical cousins, I will focus primarily on Lewis’s approach.

Ground/Consequent Thinking

In Miracles, Lewis begins by noting that everything we know about the world “beyond our own immediate sensations,” and certainly everything we know about science, is inferred.[2] “We infer Evolution from fossils,” he writes, and “we infer the existence of our own brains from what we find inside the skulls of other creatures like ourselves in the dissecting room.”[3] When we reason in this way, our inferences follow a ground/consequent pattern: because we find brains in the skulls of other beings like us (ground), we conclude that we must possess brains ourselves (consequent). More importantly, we presuppose the validity of this pattern of reasoning every time we assert the truth of an inference.

However, can we make such an assumption if strict naturalism is true? Naturalism insists that, as Lewis writes, “Nature is the whole show”—a closed physical system that operates entirely on its own according to natural causes and laws, without reliance on anything supernatural.[4] This “show” includes our reasoning faculty, which has itself been shaped through evolution by these same natural processes. In this view, there is no “outside” to reality; nothing exists independently of these basic material parts.

By definition, Nature’s creativity is aimless. While the results of evolution are non-random (as biologists correctly argue) in that they follow a predictable path of survivability, this output is merely a happy accident. It is the fortuitous convergence in which a random mutation meets the right environmental conditions that grants it an advantage. As mutations and environments are nonrational physical variables, the process remains blind and ultimately aimless. The naturalist says that it is the great ruse of the evolutionary process to fool us into thinking that it intentionally aims at anything. Lewis would add that it follows that the ruse also fools the naturalist into thinking he has intentionally thought his way to naturalism through the rules of reasoning.

Stimulus/Response Inevitability

At its most fundamental level, within the naturalist paradigm, cognition is entirely reducible to blind physical events. Cerebral activity defined in this manner cannot give rise to our conclusions based on the ground/consequent pattern. Neural firing is governed by evolution and physical laws, not the rules of logic. The ground/consequent of reason is reduced to a stimulus/response of matter. The inference—“because of the scientific evidence, naturalism must be true”—is no longer a leap of genuine insight, but a biological necessity: one neural firing caused by a previous neural firing, as mindless as a burp or a yawn. In this view, the mind is no longer “seeing” a truth but simply undergoing a material response. Lewis argues that if this kind of certainty “is merely a feeling in our own minds and not a genuine insight into realities beyond them—if it merely represents the way our minds happen to work—then we can have no knowledge.”[5]

Quantum Loophole?

Some attempt to use quantum indeterminacy to find room for rational inference, but substituting physical laws with stochastic quantum fluctuations does not correct for either the blindness or the purposelessness of the process. Ultimately, whether our minds are determined by chemistry or they emerge from the collapse of the wave function, they remain the result of non-rational activities.[6] Our experience of “seeing” a truth in light of a premise is governed by matter. Matter neither sees nor knows. Matter just is.

In this system, rational thought cannot rise beyond the level of any other impulse. Our experience of forming beliefs, such as the belief that naturalism is true, has no more validity than the burp or yawn. Thus, in such a world, the act of knowing dissolves into a meaningless vacuity.

The Naturalist’s Sacred Space

There are naturalists who try to embrace the void. Daniel Dennett describes naturalism as a “universal acid” that eats through all our concepts of mind and meaning.[7] For him, rationality is entirely explicable in terms of an evolutionary algorithm—a mindlessly arranged “heap of cranes” with no immaterial “skyhook” to guarantee its accuracy. Our experience of appealing to an external system of logic to verify our conclusions is an illusion.

Yet, his reliance on the terms “cranes” and “algorithm” reveals a curious irony: these words imply design and purpose—concepts that have no place in anything that is mindless. He is hemmed into borrowing the language of mind in order to argue that the mind does not exist. It takes a mind to see an illusion, after all. If Dennett wants to make any assertions at all, his acid cannot be universal; he must protect some sacred space of rationality from naturalism’s corrosive effects. Make no mistake, even if it’s just a rental, he is using a “skyhook.”

An Unexpected Anchor

It was this conundrum that provided an unexpected anchor for me during a season of spiritual doubt. I realized that in order to trust my doubts about God’s existence, I had to presuppose my ability to reason. Atheistic naturalism provided me with no grounds for this assumption; in fact, it actively undermined it as shown. Yet trusting my ability to reason was inescapably necessary; without it, I could not trust anything, even my doubts! I was caught in a kind of Ouroboros of skepticism—an infinite circle where my mind tried to justify its doubts using the very reasoning process it had just rendered dubious.

Darwin’s Inconsistency

Charles Darwin was also caught in this endless loop. While he confessed that he could not shake the “inward conviction” that the universe was “not the result of chance,” he understood that his theory undermined his confidence in such thoughts:

With me, the horrid doubt always arises whether the convictions of man’s mind, which has been developed from the mind of the lower animals, are of any value or at all trustworthy. Would anyone trust in the convictions of a monkey’s mind, if there are any convictions in such a mind?[8]

Nevertheless, like Dennett, Darwin exempts some aspect of mind from his own theory. He must at least rescue one conviction—the belief that his naturalism is true.

Lewis’s Consistency

C.S. Lewis, as a young atheist, was likewise troubled by this same structural flaw in naturalism, especially once he applied it to the reasoning process itself. He realized that if he wanted to maintain that abstract thought, when obedient to logic, “gave indisputable truth,” then thought could not be an event that was solely dependent upon the action of matter.[9] Again, matter “knows” nothing about the logical relationship between a premise and a conclusion. If our reasoning is entirely reducible to something that by its very nature does not reason, the former is nothing but sound and fury.

The Cosmic Logos

Our reasoning is not some arbitrary net, fashioned by millions of years of blind biological processes, that we cast over the world to make sense of it. It is not a mere cognitive adaptation that, given a different set of evolutionary circumstances, would have been woven into a different and equally arbitrary pattern. Such mindless contingency kills our cognitive confidence. It leads us directly to what G.K. Chesterton called the suicide of thought. He writes,

Reason is itself a matter of faith. It is an act of faith to assert that our thoughts have any relation to reality at all. If you are merely a sceptic, you must sooner or later ask yourself the question, ‘Why should anything go right; even observation and deduction? Why should not good logic be as misleading as bad logic? They are both movements in the brain of a bewildered ape?’ The young sceptic says, ‘I have a right to think for myself.’ But the old sceptic, the complete sceptic, says, ‘I have no right to think for myself. I have no right to think at all.’[10]

As shown with Darwin and Dennett, even the strictest naturalist is forced to allow for an invasion into his contained physical system if he wants to maintain the right to think at all. Something that is not physical must, at just the right moment, swoop in and rescue his reasoning. Even he must allow a nonphysical foot in the door at some point if he wants to keep on thinking.

Lewis concludes that reason must exist on its own, and not solely be the product of the magnificent but mindless evolutionary process, as philosophical naturalism claims. No amount of magnificence can salvage our reasoning in this scenario. He writes,

Where thought is strictly rational, it must be, in some odd sense, not ours, but cosmic or super-cosmic. It must be something not shut up inside our heads but already ‘out there’—in the universe or behind the universe: either as objective as material Nature or more objective still. Unless all that we take to be knowledge is an illusion, we must hold that in thinking we are not reading rationality into an irrational universe but responding to a rationality with which the universe has always been saturated.[11]

Furthermore, he notes, our “rationality is the little tell-tale rift in Nature which shows that there is something beyond or behind her.”[12] It is the invasive force that even the most convinced naturalist has to rely upon at some point. This opens the door to other miracles, including what Lewis calls “The Grand Miracle” of Christ’s Incarnation—an even grander invasion, if you will. Lewis would conclude “that our logic was participation in a cosmic Logos.”[13]

Hemmed In

Only Mind begets mind, and Rationality begets rationality. In my own struggles with this horrid doubt, I came to see that there must be a Mind behind the mind I use—even when I use my mind to doubt that Mind’s existence. It is a beautiful irony: the very faculty we can use to flee from Him is the one that demonstrates He is inescapable. He has hemmed us in.

Anytime I’m tempted towards skepticism, I cling to this argument with all my might, as it speaks to something even more fundamental than the act of doubting itself.

He has truly hemmed us in, behind and before. With the Psalmist, I think we can say,

Where can I go from your Spirit?

Where can I flee from your presence?[14]

Even if we make our beds in the depths of naturalism, He is there.

Notes

[1] G.K. Chesterton, St. Thomas Aquinas (Mineola, NY: Dover Publications, 2009), 95.

[2] C.S. Lewis, Miracles: A Preliminary Study (New York: HarperCollins, 1996), 20.

[3] Ibid., 21.

[4] Ibid., 6.

[5] Ibid., 21.

[6] Sir Roger Penrose argues that consciousness emerges from the collapse of the wave function; however, this remains a purely physical explanation. In his scenario, our thoughts are determined by mathematical necessity; therefore, they remain a cause-and-effect physical event. This still creates a challenge for the validity of ground/consequent reasoning, as our inferences remain the byproduct of a non-rational process rather than a genuine rational insight.

[7] Daniel C. Dennett, Darwin’s Dangerous Idea: Evolution and the Meanings of Life (New York: Simon & Schuster, 1995), 63.

[8] Charles Darwin to William Graham, July 3, 1881, letter 13230, Darwin Correspondence Project, accessed March 13, 2026, https://www.darwinproject.ac.uk/letter/?docId=namelookup/xml/DCP-LETT-13230.xml.

[9] C.S. Lewis, Surprised by Joy: The Shape of My Early Life (New York: Houghton Mifflin Harcourt), 208, Kindle.

[10] G.K. Chesterton, Orthodoxy (London: John Lane Company, 1908), 25-26, Kindle.

[11] C.S. Lewis, Christian Reflections, ed. Walter Hooper (New York: HarperCollins, 2014), 80, Kindle.

[12] C.S. Lewis, Miracles, 44.

[13] C.S. Lewis, Surprised by Joy, 209, Kindle.

[14] Psalm 139:7, NIV.

— Rebekah Valerius has a B.S. in biochemistry and an MA in apologetics. She teaches advanced chemistry and biology and apologetics at a classical Christian school in the Dallas area.