The Argument from Reason (an Introduction)

by Josh Hickok

“…Nature is quite powerless to produce rational thought: not that she never modifies our thinking but that the moment she does so, it ceases (for that very reason) to be rational.  For, as we have seen, a train of thought loses all rational credentials as soon as it can be shown to be wholly the result of non-rational causes.” [1] 


     The argument from reason (AR) has a very short and (supposed) troubled past.  After becoming a bit more vocal with this argument, Mr. Lewis had a confrontation with an Elizabeth Anscombe that had an enormous psychological impact on Lewis and his methods of apologetics[2].  Unfortunately, the debate with Anscombe led many to believe the AR was deeply flawed and pushed it into oblivion, handing naturalism a decisive victory.  Was this victory a bit too hasty, and is there something to the AR?  There has been renewed interest in Lewis’ argument in recent years, even getting a newer formulation from Christianities most prolific contemporary philosopher. 

     Before we try and understand the debate surrounding the AR, we must understand the target- naturalism.  This word is not as straightforward as it used to be in Lewis’ day- there are at least two major divisions in the naturalist camp; those that claim the physical realm is all that exists (call them ontological naturalists) and those who claim that only the physical realm is knowable, through the empirical sciences (call them methodological naturalists).  It is my belief that the second kind of naturalists may as well be the former.  In practice, there is no difference between them- both rely heavily on the promise of science and both scoff at any metaphysical speculation (except, of course, their own metaphysical charge against supernaturalists).  With this in mind we will focus on the ontological naturalists.

I. Naturalism’s Framework

     So what can naturalism possibly say about reason it shouldn’t?  We must come to an understanding of what naturalism is built on.  Because we are focusing our attention on ontological naturalism, we must conclude that there is no outside interference in the rationality forming process- that is, the only thing that can influence our mental states are physical causes.  Of course, this flies in the face of most theists, especially Christians who rely heavily on the doctrine of the soul.  To tell a Christian that the physical is all that exists would be like telling a bank that there is no such thing as money.[3]  So the first premise of Naturalism would roughly state-

1)      Everything that exists lies in the domain of the purely physical.

     You could also change this a bit to fit the agnostic naturalists-

1)      Only physical entities have causal powers.

     This next section is a little hairier.  In order to show naturalism inconsistent with its very claims, we must defend the claim that when we do reason, we must come to truth (or at least an approximation of it).  Remember that at the outset naturalists say that one thing is true- namely, their belief about the ontological status of the universe and anything beyond it.  But to remain consistent with premise 1, naturalists will say that reason and our belief-forming processes are the result of unguided physical causation.  So we have our next premise-

2)      Reason is the result of purely physical causes.

     Though not all naturalists, physicalists and atheists can be pegged so easily, I believe (along with others) that these two premises correctly define the general outlook they have for reality. With that being said, we can now move to the AR.

II. The Argument from Reason

     To borrow the argument from Victor Reppert[4], this is the general outline we will use (though he makes mention of more than five different forms)-

1)      If naturalism is true, then no states of a person can be either true or false.

2)      Some states of a person can be true or false.

3)      Therefore, naturalism is false.

     In defense of 1, I think we may need to qualify it a bit.  If naturalism were true, then our beliefs (about even naturalism) were caused by non-rational causes.  There is nothing true or false about the physical in and of itself, so we have no reason to think that we as humans were geared to properly discover truth (given that nothing but physical causes produced our beliefs).  Some may object on evolutionary grounds and say that in the struggle for survival our cognitive faculties began to uncover the true nature of the universe.  This would just seem demonstrably false.  If survival, not truth, is the virtue that the entire universe tends towards, then truth would become superfluous in some cases, and possibly an enemy in others.  What good would it do for our faculties to provide us with true knowledge of how things actually work?  In that case, what good would it do to debate things that have little to no bearing on our survival probabilities? 

     Those that say we can interchange empirical reliability with truth are sorely misguided.  This notion is loaded with presuppositions, but even more apparent is its mistreatment of the way our minds work.  Perhaps we do receive a completely reliable and consistent sensory input from the external world, but it is just as likely in a naturalist universe that it is consistently false as it is true.  Consider the following quote from Patricia Churchland:

     “Boiled down to essentials, a nervous system enables the organism to succeed in… feeding, fleeing, fighting, and reproducing.  The principle [sic] chore of nervous systems is to get the body parts where they should be in order that the organism should survive.  Improvements in sensorimotor control confer an evolutionary advantage: a fancier style of representing is advantageous so long as it is geared to the organism’s way of life and enhances the organism’s chances for survival.  Truth, whatever that is, takes the hindmost.”[5]

     As you see here, truth is another enterprise altogether- this takes us to point number 2.  If this hasn’t struck you as odd yet, perhaps we should reconsider the base claim of naturalism- physical events have physical causes.  Now how would the naturalist have come to this claim?  If truth is nothing but an afterthought, or at best a speculative generalization, how could they possibly have reached the truth on this matter?  That is, if there is no such thing as truth, it wouldn’t seem we could believe they were telling us the truth about the nature of the universe.  In fact, we probably are quite justified to just ignore the whole cadre they’ve built.  Perhaps David Hume was right when he said “’Tis happy, therefore, that nature breaks the force of all skeptical arguments in time, and keeps them from having any considerable influence on the understanding.”[6]

[1] C.S. Lewis, Miracles, Chap. 4.  Lewis is one of the first to formally put forward this epistemological challenge to naturalists. It is worth noting that the actual location of the argument is in Chapter 3 of the book.

[2] At least, this is the account recorded by A.N. Wilson which is most assuredly embellished, if not groundless.

[3] There is a small minority of Christian philosophers who believe that the soul is not “other than” than matter, but this view has such a small following that it would be pragmatically useless to treat.

[4] Victor Reppert, C.S. Lewis’s Dangerous Idea, p. 77-78.

[5] Patricia Curchland, “Epistemology in the Age of Neuroscience”, Journal of Philosophy 84 (Oct. 1987):548.

[6] David Hume, A treatise of Human Nature, Oxford Clarendon Press, 1988 p. 187.


(Back to articles