C.S. Lewis’s Transcendental Argument for God

“Unless I believe in God, I can’t believe in thought: so I can never use thought to disbelieve in God.”
-C.S. Lewis, The Case for Christianity, pg. 32

C.S. Lewis is one of the most popular Christian apologists of the 20th century, and arguably, one of the most read apologists of all time. His approach to the defense of the faith was fairly unsystematic, which can make categorizing his apologetic method difficult. In fact, he used lots of different methods, mediums, and arguments in his efforts to stave off attacks and go on the offensive against unbelief. While I thoroughly enjoy many of his arguments, especially the moral argument he used in Mere Christianity and the imaginative approach he took in the Chronicles of Narnia, my favorite Lewis argument is without a doubt his “Argument from Reason”.

The Argument From Reason
Lewis’s argument from reason is usually associated with the first six chapters, as well as the thirteenth chapter of his phenomenal book, Miracles. But he employed this argument throughout many of his works; it’s actually one of the most consistent through lines in Lewis’s massive corpus.

Lewis came to embrace the argument from reason after he felt it’s force himself as an unbeliever. In his book, Surprised By Joy, he recounts that his friend, Owen Barfield, helped destroy his atheism and convince him that only a theistic view could leave room for any satisfactory theory of knowledge. It’s in this book that we get one of Lewis’s most concise summations of his argument from reason, “Unless I were to accept an unbelievable alternative, I must admit that mind was no late-come epiphenomenon; that the whole universe was, in the last resort, mental; that our logic was participation in a cosmic Logos.” (Surprised By Joy, pg. 209). The argument purports that reason itself is evidence for God.

As philosopher Victor Reppert notes, the argument from reason is really a family of arguments and might be more accurately called “the arguments from reason”. Over the years lots of philosophers have appreciated Lewis’s argument and worked hard to strengthen it and appropriate it for different uses. Stewart Goetz has applied it as a deductive argument against Naturalism. Reppert has put forward several formulations as reductio ad absurdum arguments against Naturalism, focusing in primarily on Naturalism’s inability to account for rational inference. Alvin Plantinga uses the argument as a “skeptical threat” argument against Naturalism, arguing basically that if Naturalism were true we couldn’t know it to be true (though to my knowledge, his only credit to Lewis is a single footnote on the last page of his book Warrant and Proper Function). William Hasker has proposed that the argument be viewed as a Best explanation argument, and Angus Menuge has even presented an “Ontological Argument from Reason”.

These formulations (along with even more) continue to serve as insightful critiques of Naturalism while providing evidence for God. However, one of the most powerful forms of the argument seems to be the least utilized: C.S. Lewis’s Transcendental Argument from Reason. Though William Hasker has proposed the Argument from Reason might be best formulated as a transcendental argument, I don’t see a lot of people doing it. I heartily agree with Hasker and so in this post I’ll do my best to show how the Argument from Reason is a very compelling transcendental argument for God.

A Bit About Transcendental Arguments
Before we see how Lewis’s argument from Reason can be formulated as a powerful transcendental argument, we better take some time to understand what exactly a transcendental argument is. As if I hadn’t already used enough weird words, we now have to deal with “transcendental” but fortunately it’s not as weird as it sounds. Philosophers Julian Baggini and Peter Fosl encourage us that “despite it’s name, this sort of argument has nothing to do with Eastern religion or meditation. It is, rather, a cool, calm analytic procedure most notably used by Immanuel Kant (1724-1804).” (The Philosopher’s Tool Kit, pg. 218). There may be other instances of transcendental arguments before Kant, but if we want to blame someone for the name, it’d be safe to blame him, “in transcendental knowledge, so long as we are concerned only with concepts or the understanding, our guide is the possibility of experience.” (Critique of Pure Reason, Kant, A783/B811)

Just like the argument from reason, Transcendental arguments are a family of arguments, with lots of formulations, patterns, and purposes, but there is a definite essence to the argument that unifies them. James Anderson says, “If there is any consensus on the nature of the transcendental premise, it is that the premise must at least express a necessary condition of some essential feature of human thought or experience.”(No Dilemma for the Proponent of TAG, James Anderson, Philosophia Christi 11, no. 2 (2009). Similarly, A.C. Grayling says, “What is typical of TAs proper is that they purport to establish the conditions necessary for experience, or experience of a certain kind, as a whole; and, at their most controversial, to establish a conclusion about the nature and existence of the external world, or other minds, as these – and particularly the world’s existence – can be derived in consequence of paying attention to what has to be the case for there to be experience, or in order for experience to be as it is.” (The Refutation of Skepticism, pg. 83). So the common thread between all TA’s is that they start with a given, some incontrovertible experience, and seek to answer the question: “what must be true given this experience.”

Here’s a good place to introduce the term “presuppositions”. Transcendental arguments use presuppositional reasoning, which is an indirect method, instead of the direct approach of deductive or inductive arguments. According to Harry Gensler, “A deductive argument claims that it’s logically necessary that if the premises are all true, then so is the conclusion. An Inductive argument claims that it’s likely (but not logically necessary) that if the premises are all true, then so is the conclusion.” (Introduction to Logic, pg. 81).

A Transcendental or Presuppositional argument differs from traditional arguments in that if A presupposes B, then B is the necessary precondition of A such that if B were not true then A can be neither true nor false. Now I know that might be hard to understand at first but bare with me.

Two of the most widely known proponents the presuppositional method (besides Kant) are P.F. Strawson and Bas Van Frassen, so let me quote Van Frassen quoting Strawson to cover all my bases. Van Frassen says,

The best known source for the concept of presupposition is the view (a.o. Strawson’s) that a property cannot be either truly or falsely attributed to what does not exist. Thus, the sentence “The King of France (in 1967) is bald” is neither true nor false, on this view, because the King of France does not exist. The explicit characterization of presupposes is therefore given by

1. A presupposes B if and only if A is neither true nor false unless B is true.
This is equivalent to
2. A presupposes B if and only if
(a) if A is true then B is true
(b) if A is false then B is true
(“Presupposition, Implication, and Self-Reference”, Bas Van Frassen, Journal of Philosophy, Vol. 65, No. 5, pg. 137)

So in a normal deductive argument you could argue:

(1) If A then B
(2) A
Therefore B
Which demonstrates the deductive principle known as “modus ponens”.

You could also argue:

(1) If A then B
(2) -B (not B)
Therefore, -A (not A)

Which demonstrates the deductive principle known as “modus tollens”. In denying the consequent you show premise (1) to be false.

However, as stated above, a presuppositional argument is different from a deductive argument such that modus ponens is valid but modus tollens is not.

(1) A presupposes B
(2) A
Therefore B
This is a valid presuppositional syllogism.

But if we deny the consequent, B, of the presuppositional argument, then A is neither true nor false since it depends on B for it’s truth or falsity.

(1) A presupposes B
(2) -B
Therefore A is neither true nor false since B is the necessary precondition for the truth or falsity of A.

If this is your first time seeing a presuppositional argument then you are most likely confused at this point but let’s return to the King of France statement to flesh this out. The statement “the King of France is Bald” presupposes that there is a King of France. If there is a King of France then we can either affirm that this statement about his baldness is true or deny it as false. But if there is no King of France then this statement is neither true nor false, the king is neither bald nor does he have a full head of hair, for the King doesn’t exist. This is called “a failure of presupposition”. Now, you might be wondering to yourself, “Self, can’t I just say the statement is false since there is no king?”. But to say that the statement “the King of France is bald” is false is to affirm that there is a king of France, you’ve bought into the false presupposition. Thus, the appropriate answer to the statement is to say that it is neither true nor false since there is no King of France. This is the gist of a presuppositional argument and this is why Strawson and Van Frassen can say that

A presupposes B if and only if
(a) A presupposes B
(b) -A presuppose B

Since B is the necessary precondition of the truth or falsity of A, both A and -A presuppose B. If i’m starting to sound like Vizzini from the Princess Bride then just hold tight, it’ll all become more clear when we get to Lewis in the next section and we start plugging in the A’s and B’s with concepts and phrases.

Robert Stern reminds us at this point that “transcendental arguments are usually said to be distinctive in involving a certain sort of claim, namely that ‘For Y to be possible, X must be the case’, where Y is some indisputable fact about us and our mental life (e.g. That we have experiences, use language, make certain judgements, have certain concepts, perform certain actions, etc.)” (Transcendental Arguments and Scepticism, pg. 6). So if A stands from human thought (the given) then B would stand for a necessary precondition of human thought- something that is presupposed by the existence of thought, something that makes sense of it.

Now as you might guess, transcendental arguments are a bit controversial. The strong claims made by TAs have led some to argue that they “have all the advantages of theft over honest toil.” And others, like Moltke S. Gram, have even said that “The problem about transcendental arguments is whether there are any.” TAs have been discussed and debated ever since Kant and while there isn’t a settled consensus on their validity, Don Collett reminds us that “From this it does not follow, however, that Christian apologists are somehow bound to share in Gram’s skepticism with respect to transcendental arguments.” (“Van Til and Transcendental Arguments” in Revelation and Reason, pg. 278). With that in mind, we’re now ready to examine C.S. Lewis’s Transcendental Argument for God from Reason.

Part 1. Human Thought and Reason
Lewis’s argument can be understood as a two part transcendental argument: Part 1. seeks to show that human thought presupposes Reason, i.e. the Laws of Logic, and part 2. seeks to demonstrate that Reason Presupposes God.

As I said earlier, the argument from reason is a consistent through line in the Lewis corpus. Whether he’s dealing with early forms of Postmodernism, or Subjectivism, or Darwinian Naturalism, or Nihilism, or Freudianism, or Marxism, or any other “ism”, Lewis has no time for the discrediting of Reason. In Miracles, he explains that “no account of the universe can be true unless that account leaves it possible for our thinking to be a real insight. A theory which explained everything else in the whole universe but which made it impossible to believe that our thinking was valid, would be utterly out of court. For that theory would itself have been reached by thinking, and if thinking is not valid that theory would, of course, be itself demolished. It would have destroyed its own credentials. It would be an argument which proved that no argument was sound – a proof that there are no such things as proofs- which is nonsense.” (Miracles, pg. 21-22).

Lewis really enjoys attacking the thought that there can be “a proof that there are no proofs”. He refutes that claim in Miracles, Pilgrim’s Regress (pg. 71), “The Funeral of A Great Myth” (Christian Reflections, pg. 111), “Meditations in a Tool Shed” (CompellingReason, pg. 55), and “Bulverism” (Compelling Reason, pg. 20), to name a few. But I digress.

Lewis starts his transcendental argument with the incontrovertible position that humans have thoughts and that some human thoughts can be true. In one of his best essays, De Futilitate, he says “In other words, we are asking ‘is the thought that no thoughts are true, itself true?’ If we answer Yes, we contradict ourselves. For if all thoughts are untrue, then this thought is untrue.” (In Christian Reflections, pg. 75). 

As Robert Stern notes in regards to starting a TA, “we [start] with something which the sceptic cannot deny is actual, and therefore possible, so that our starting-point does not require any further justification.” (Transcendental Arguments and Scepticism, pg. 8). So Lewis, in that light, starts with human thought.

Next, Lewis, thinking transcendentally, argues that human reasoning, or thinking, presupposes big “R” Reason, or the laws of logic, which are necessary, universal, immaterial, and independent of the human mind. Correct and incorrect human reasoning both presuppose Reason as we saw earlier that A and -A both presuppose B. But if Reason is invalid then human thinking is nonsensical, neither true nor false.

Lewis fleshes out the distinction between human thought and Reason in De Futilitate so we’re able to see the presuppositional relationship, “As I have said, there is no such thing (strictly speaking) as human reason: but there is emphatically such thing as human thought- in other words, the various specifically human conceptions of Reason, failures of complete rationality which arise in a wishful and lazy human mind utilizing a tired human brain. The difference between acknowledging this and being sceptical about Reason itself, is enormous. For in the one case we should be saying that reality contradicts Reason, whereas now we are only saying that total Reason – cosmic or super-cosmic Reason –corrects human imperfections of Reason… To say that Reason is objective is to say that all our false reasonings could in principle be corrected by more Reason.” (In Christian Reflections, pg. 83-84). The fact that humans can reason correctly and incorrectly presupposes the existence of a standard by which to judge human thoughts as correct or incorrect, thus human thought presupposes objective Reason.

Even more aggressively, in The Abolition of Man, Lewis says,“An open mind, in questions that are not ultimate, is useful. But an open mind about the ultimate foundations either of Theoretical or of Practical Reason is idiocy. If a man’s mind is open on these things, let his mouth at least be shut.” (pg. 48). And again in Miracles, he says “If the value of our reasoning is in doubt, you cannot try to establish it by reasoning. If, as I said above, a proof that there are no proofs is nonsensical, so is a proof that there are proofs. Reason is our starting point. There can be no question either of attacking or defending it. If by treating it as a mere phenomenon you put yourself outside it, there is then no way, except by begging the question, of getting inside again.” (pg. 33). Again, Lewis makes the point that human thought presupposes Reason; Reason itself is the necessary precondition of the truth or falsity of human reasoning.

Lewis presses the point that Reason cannot be proven directly by a deductive argument, since all such arguments presuppose the validity of Reason. However, if you presuppose Reason then you can make sense of human thought, be it valid or invalid. Reason is proven indirectly through transcendental argument rather than directly. Without it, human thought can be neither true nor false. If you take away the measuring rod, there’s no way to tell who’s off.

While transcendental reasoning has been tacit in the quoted sections thus far, there are at least two instances where Lewis comes right out and says his argument is transcendental. The first comes from the essay “Bulversim”, where he says

 “The forces discrediting reason, themselves depend on reasoning. You must reason even to Bulverize. You are trying to prove that all proofs are invalid. If you fail, you fail. If you succeed, then you fail even more – for the proof that all proofs are invalid must be invalid itself. The alternative then is either sheer self-contradicting idiocy or else some tenacious belief in our power of reasoning, held in the teeth of all the evidence that Bulverists can bring for a ‘taint’ in this or that human reasoner. I am ready to admit, if you like, that this tenacious belief has something transcendental or mystical about it. What then? Would you rather be a lunatic or a mystic?” (Compelling Reason, pg. 20).

And the second instance comes from his essay, “Religion Without Dogma?”,

“The Validity of rational thought, accepted in an utterly non-naturalistic, transcendental (if you will), supernatural sense, is the necessary presupposition of all other theorizing. There is simply no sense in beginning with a view of the universe and trying to fit the claims of thought in at a later stage. By thinking at all we have claimed that our thoughts are more than mere natural events. All other propositions must befitted in as best they can round that primary claim.” (ibid. pg. 94). This last quote especially shows that in his view, objective Reason is the necessary precondition for the truth or falsity of human thought.

All that to say, correct human thought presupposes Reason and incorrect human thought presupposes Reason.

With that dead horse thoroughly beaten, we can now move on to the controversial part 2: Reason presupposes God.

Part 2. Reason and God
As we’ve seen from part. 1, human thought presupposes Reason, but that’s not the end of the story. In part 2 we take Reason as our given and ask what must be the case for Reason to be intelligible; given Reason, what are it’s necessary preconditions? Following up on part 1 of his transcendental argument, Lewis says “So we see there is justification for holding on to our belief in Reason. But can this be done without theism? Does ‘I know’ involve that God exists?”( “Bulverism”, in Compelling Reason, pg. 21). 

Lewis answers his own question in the affirmative, “There are all sorts of different reasons for believing in God, and here I’ll mention only one. It is this. Supposing there was no intelligence behind the universe, no creative mind. In that case nobody designed my brain for the purpose of thinking. It is merely that when the atoms inside my skull happen for physical or chemical reasons to arrange themselves in a certain way, this gives me, as a bye-product, the sensation I call thought. But if so, how can I trust my own thinking to be true? It’s like upsetting a milk-jug and hoping that the way the splash arranges itself will give you a map of London. But if I can’t trust my own thinking, of course I can’t trust the arguments leading to atheism, and therefore have no reason to be an atheist, or anything else. Unless I believe in God, I can’t believe in thought: so I can never use thought to disbelieve in God.” (The Case for Christianity, Lewis, pg. 32).

And again in Miracles,
“If Naturalism is true we have no reason to trust our conviction that Nature is uniform. It can be trusted only if quite a different Metaphysic is true. If the deepest thing in reality, the Fact which is the source of all other facthood, is a thing in some degree like ourselves – if it is a Rational Spirit and we derive our rationality from It – then indeed our conviction can be trusted.” (pg. 168).

Only if God is the ultimate Fact, does Reason and human thought make sense. God serves as the ultimate presupposition, and if God fails to be real then we have a failure of presupposition when it comes to objective Reason and thus human thought can neither be true nor false.

Lewis answers the question of the preconditions of Reason in an Augustinian fashion. If human thought is to be rational, then there must be an objective Reason outside of humanity, if there is to be an objective Reason outside of humanity, then God must exist as the precondition for Reason and for man’s ability to engage in reasoning. Lewis explains that a Theist “is not committed to the view that reason is a comparatively recent development molded by a process of selection which can select only the biologically useful. For him, reason- the reason of God – is older than Nature, and from it the orderliness of Nature, which alone enables us to know her, is derived. For him, the human mind in the act of knowing is illuminated by the Divine reason.” (Miracles, pg. 34).

And again, “The supernatural Reason enters my natural being not like a weapon- more like a beam of light which illuminates or a principle of organization which unifies and develops.” (ibid. pg.48).

These quotes serve to show that Lewis’s ultimate presupposition is God and without God we can’t know anything. Without God, objective Reason and human thought come crumbling down. But Lewis doesn’t merely assert a dogmatic notion and leave it at that. In demonstrating that human thought presupposes Reason and Reason presupposes God, Lewis is at his best! He says, “what exists on its own must have existed from all eternity; for if anything else could make it begin to exist then it would not exist on its own but because of something else. It must also exist incessantly: that is, it cannot cease to exist and then begin again. For having once ceased to be, it obviously could not recall itself to existence, and if anything else recalled it it would then be a dependent being. Now it is clear that my Reason has grown up gradually since my birth and is interrupted for several hours each night. I therefore cannot be that eternal self-existent Reason which neither slumbers nor sleeps. yet if any thought is valid, such a Reason must exist and must be the source of my own imperfect and intermittent rationality. Human minds, then, are not the only supernatural entities that exist. They do not come from nowhere. each has come into Nature from Supernature: each has its tap-root in an eternal; self-existent, rational Being, whom we call God. Each is an offshoot, or spearhead, or incursion of that Supernatural reality into Nature.” (Miracles, pg. 42-43).

That in summary, is C.S. Lewis’s Transcendental Argument for God from Reason!

Here we have it in syllogistic form:
(1) Human thought presupposes Reason
(2) Reason presupposes God
(3) Human thought
Therefore, God.

Man can’t think without Reason, but Reason isn’t dependent on mans thoughts. Reason’s taproot is God, whether we believe that Reason is an attribute of God or Reason is analogically related to God’s character, Reason presupposes God. Since we’ve been made in God’s image, God has made us with the ability to engage in reasoning. God’s thought is original and eternal, ours is derivative and finite.

If Lewis’s argument holds, if human thought presupposes objective Reason, and objective Reason presupposes God, then all human thought, be it Christian, Atheist, or otherwise, be it correct or incorrect, all human thought presupposes God. Remember back to Strawson and Van Frassen:

A presupposes B if and only if
(a) A presupposes B
(b) -A presuppose B

If A stands for a correct human inference and B stands for God, then correct inferences and incorrect inferences presuppose that God exists.

James Anderson and Greg Welty, in the same vein as Lewis, rightly observe that “If the laws of logic are metaphysically dependent on God, it follows that every logical argument presupposes the existence of God. What this means is that every sound Theistic argument not only proves the existence of God but also presupposes the existence of God, insofar as that argument depends on logical inference. Indeed, every unsound theistic argument presupposes the existence of God. And the same goes, naturally, for every antitheistic argument. The irony must not be missed: one can logically argue against God only if God exists.” (From “The Lord of Noncontradiction”, in Philosophia Christi volume 13, No. 5, 2011, pg. 337).

Lewis’s Transcendental Argument may have a lot of entailments and may need the amount of explanation I gave, if not more, but at it’s core, the argument is simple: “Unless I believe in God, I can’t believe in thought: so I can never use thought to disbelieve in God.” -C.S. Lewis, The Case for Christianity, pg. 32

Some may ask, “well, which God does this argument presuppose?” to which I would reply, there is only one God, YAHWEH. If asked for a demonstration on how this argument presupposes the Christian God of the Bible and not another god, I would say that the unity and diversity presupposed by human thought, itself, presupposes the Trinitarian God of the Bible who is one Essence, Three Persons. But that’s an argument for another time and brings us outside the scope of this incredibly long blog post.

*cover picture is a screenshot from CSLewisDoodle’s YouTube video “Bulverism by C.S. Lewis Doodle (The Foundation of 20th Century Thought”


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