April 16, 2009

A Short Post on the Argument from Reason (AfR)

Posted in Answering Apologists, Atheism tagged , , , , , , , , at 4:38 pm by Andrew

I very much enjoy Victor Reppert’s Christian blog, “Dangerous Idea,” although obviously I disagree with his conclusions. Reppert’s favorite argument is a modern version of C.S. Lewis’s “Argument from Reason” (AfR); he posts a brief summary of its claims here.

In a recent post, Reppert also commends an article in the Calgary Herald that supposedly sets forth an application of the AfR.

Here’s the problem. The author, Hugo Maynell, summarizes the AfR as follows:

C. S. Lewis argued that scientific materialism is ruined by one fundamental inconsistency. Its proponents asked him to believe, in the name of science, that reason had arisen in the universe as a result of particles of matter moving randomly about over an enormous lapse of time. This is scientism, not science. Science, as Lewis said, depends on the assumption that reason is an absolute; furthermore, that matter in the remotest galaxies conforms to thought-laws excogitated by scientists in their laboratories here on Earth. (emphasis added)

If that’s what C.S. Lewis said, then C.S. Lewis is just flat wrong, and the AfR need not be taken seriously. I don’t want to straw-man a serious argument if it exists, but this claim is nonsense. No serious atheist I know — not the most dedicated, hardcore materialist — claims that reason is “an absolute.” Rather, we look to science as a way of discovering facts about the world because it’s been inductively reliable so far.

Now a fair response to the atheist would be to cite the problem of induction, for example. But it straw-mans the atheist to insist that the he must prove that reason is an “absolute.” We know that reason misleads us all the time. It just so happens it’s the best tool we’ve got.


  1. I don’t have a good response to your post. (Deep stuff. Admittedly, I have not read C.S. Lewis.) I appreciate your humane approach to dialogue šŸ˜‰ as I’m sure you know the back and forth between atheists and theists can get really ugly. I personally do not think there is ever a reason to resort to such ugliness. Anyway, just wanted to let you know I revisited Becky’s blog today and saw you had responded to one of my comments. I gave you a “shout” back. Well, actually it wound up being a rather long comment…


    You have a nice blog going here. Good to “meet” you.

  2. Steven Carr said,

    Particles do not move ‘randomly’ about.

    Doesn’t Lewis say elsewhere that atheists have to believe in determinism?

    So particles move about randomly in a deterministic manner….

    Was Lewis capable of not contradicting himself?

    It is very hard to produce a really good refutation of Lewis.

    You can’t really nail his arguments. It is like trying to nail jelly to a wall.

  3. […] at 10:46 am by Andrew Christian Science Fiction fan Jessica Thomas, in the comments to a previous post, references a post she made elsewhere that responds to my basic question as to why God […]

  4. Robert Ritchie said,

    You have not understood the argument.

    Think of it this way:

    If my mental processes are determined wholly by the motions of [matter] in my brain, I have no reason to suppose that my beliefs are true … and hence I have no reason for supposing my brain to be composed of [matter]…

    and I have no reason for supposing anything else my mind tells me is true, fore example materialism.

    Thus materialism is self refuting. Why don’t you attack some of the premises of the argument you linked to on Reppert’s site? That will make sure you don’t misinterpret what the argument says.

    • Andrew said,

      1. What’s the warrant for your assertion in your first paragraph?

      2. Why don’t you respond to the criticism I’ve made of this particular formulation of the AfR, which makes unfounded assertions? (I invited Victor to do the same, and the most he came up with was something like, ‘well, this was probably written pretty colloquially.’)

      3. Materialism is not equivalent to atheism.

  5. Robert Ritchie said,

    1. You are using “reason is an absolute” to mean we never make mistakes when we attempt to reason. Lewis means only that we can use our power of inference to reach truth even though we may be mistaken.

    2. ditto

    3. Absolutely true. And the AfR is not meant to attack anything but materialism. For example, Thomas Nagel is an atheist and wrote and extended defense of the AfR in his book The Last Word.

  6. Robert Ritchie said,

    The argument as it is listed on the link to Reppert’s site makes this very clear. And see the Wikipedia entry which should help clear some things up too.


  7. Jim Donaldson said,

    I don’t think the wikipedia version that Reppert copied was written colloquially at all. If you’d actually address the numbered arguments I think you’d see that they’re pretty sound. To deny them you’d have to say things like mindless material can arrange itself in a way that a mind develops to control the arrangement. I guess you could make that argument, but this is not an “unfounded assertion.”

    • Andrew said,

      I pass no judgment on Reppert’s defense (or lack thereof) of Maynell.

      However, when Maynell says:

      Science, as Lewis said, depends on the assumption that reason is an absolute

      Then Maynell either (a) has no idea what science is, or (b) doesn’t care. Either way, that’s not really a good argument for theism.

      • Facilis said,

        So reason isn’t absolute??
        Reason doesn’t apply to God or Christianity. Now your blog is worthless.

      • Robert Ritchie said,

        I assure you that is not what he meant. He meant that science depends on the assumption that reason is an absolute (in the sense I keep describing and that materialism leaves no room for this assumption. Therefore materialism is self-refuting. Please stop assuming these people are such morons, they aren’t going to make such obvious mistakes, I promise

  8. Robert Ritchie said,

    Ok, if you think he means that “reason is an absolute” means we never make a mistake, he is obviously wrong. But this is absurd.

    First of all, Lewis had nothing against science. He thought reason was an absolute. And obviously he thought people made mistakes. So what did he mean.

    He meant it as shorthand as it were for the idea the the laws of reason are an absolute. That, for example, the law of non-contradiction is an absolute. And, what’s more, he thought humans could infer from sense data with regard to the laws of reason to truth. He said science (or any pursuit of truth) depends on this assumption. But materialism refutes this assumption. Therefore materialism is self-contradictory.

    I assure you that “the assumption that reason is absolute” is not the assumption that humans never make errors when exercising their power of reasoning. You should, as I keep saying, read the numbered argument so that this comes through instead of setting up this straw man.

  9. Andrew said,


    It sounds to me that you are confusing the AfR with various forms of TAG (discussed elsewhere on this site); you’re talking about the laws of logic more than just reason generally.

    The AfR says that we have no evolutionary reason to believe that our reason is reliable. One obvious answer is that our reason is not entirely reliable, which is exactly what we would expect from an evolutionary process.

  10. Robert Ritchie said,

    That is not it. The AfR is about why we can reason at all. If you would read the numbered arguments you would get it. Why do you insist on assuming you know what the argument is when the numbered argument makes it extremely clear and is at your fingertips?

  11. Robert Ritchie said,

    For example, if you look at the comments on the link you provide to Reppert’s site, you will see people actually grappling with the issues you say are not part of the argument. Here’s one, for example:

    I think 2 & 8 are the same assertion. They strike me as axiomatic, which is essentially what the page says later:

    “One cannot form a combination of one thing to create another which is different in kind from it. For example, say we definitively found that there exists two and only two kinds of irreducible physical particles A and B. One could not combine A with itself to produce B. B is different in kind than A. Similarly, Hume teaches that you cannot reach a conclusion in the imperative mood from premises in the indicative mood (i.e. you can’t get an ought from an is). Assertions in the one mood are different in kind from assertions in the other. Therefore, likewise the rational ability to control matter cannot arise from mere matter itself (i.e. element eight).

    Therefore, even if the universe has always existed and is uncreated, this argument holds that it would not be possible for non-rational materials to arrange themselves in such a way that rationality would arise. Therefore, a rational being that did not begin to exist is required for the assumption that humans can be convinced by argument to be upheld.

    There is a problem with denying element nine. If rationality could spontaneously enter our experience, where would it come from? That is, the denial of element nine implies existence springing forth from non existence, which is impossible (See Aristotle, Metaphysics III, 4, 999b, 8; Arguing that the impossibility that generation should take place from nothing is self-evident).”

  12. Cody said,

    I think you might be taking that bit of the argument too far. It is true that scientific naturalism posits that we can learn about the world around us using reason, and so it is essential to any of the conclusions it reaches. So I think you’re playing with words a little bit. Reason is paramount, but not technically “absolute.”

  13. WalterD said,

    Maynell got it wrong.

    In his original argument, Lewis didn’t say that reason was an “absolute”. What he said was that the laws of reasoning — deductive and inductive logic — are correct. They allow us to gain actual knowledge about the natural world.

    Randomly moving particles aren’t a part of Lewis’s argument either. He mentions quantum mechanics briefly but he admits he doesn’t understand it well, and he doesn’t base any aspect of his argument on it.

    All the sources I’ve seen that try to summarize the AfR do it rather poorly. If you can find a copy of “Miracles” and read Chapter 3, where Lewis spends a good 20 pages fleshing out the AfR. It’s much more thorough and less… stupid sounding… than Maynell’s summary.

  14. Metacrock said,

    you misunderstand the argument from reason. He’s not saying atheist think reason is absolute he is saying reason is absolute. the problem with naturalism is it reduces reason to nothing but a by product of chemicals and so on. But by the nature of reason should be accounted for through a p0rocess of reason not of non-cognitive forces.

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