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WillowOne's Positions

Argument from Reason

Form

C. S. Lewis's argument (Miracles, 1947, ch. 3), revived by Victor Reppert (C. S. Lewis's Dangerous Idea, 2003), with ancestors in Arthur Balfour and J. B. S. Haldane: "If my mental processes are determined wholly by the motions of atoms in my brain, I have no reason to suppose that my beliefs are true."

  1. If naturalism is true, every belief is fully explained by non-rational causes: the motion of atoms, the chemistry of neurons, the pressures of evolution.
  2. A belief that is fully explained by non-rational causes is not held because of reasons, and so is not rationally grounded.
  3. So, on naturalism, no belief is rationally grounded, including the belief in naturalism.
  4. Naturalism is therefore self-refuting. Reason must have a source that is itself rational, and that source is God.

My Positions

  1. It confuses the causal history of a belief with its justification. A calculator is caused entirely by physics and its outputs are correct, because the physical process implements the logical one. A brain can likewise be a physical system whose states track reasons, because it was built, by selection and learning, to do so. "Caused by atoms" and "held because of reasons" are not competitors; the second is a description of what a certain arrangement of the first does (Functionalism, Substrate Independence). This is the Genetic Fallacy applied to one's own thoughts.
  2. Lewis lost this argument in public and rewrote the chapter. At the Oxford Socratic Club in 1948, Elizabeth Anscombe pointed out that he had run together "irrational" causes with "non-rational" causes, and that showing a belief has a physical cause does nothing to show it was arrived at irrationally. Lewis conceded, and the 1960 edition of Miracles carries a revised and weaker version. Reppert's revival restates the original without the concession.
  3. The argument assumes that if reasoning has a physical explanation it is not reasoning. That is dualism as a premise, not a conclusion, and it is the Argument from Consciousness in epistemic clothing. Computers perform valid inference. Nobody thinks the silicon is being irrational.
  4. It proves too much, in both directions. If God's reasoning is determined by God's nature, it is as "caused" as mine. And the theist's beliefs are also produced by neurons; if neuronal causation undermines belief, it undermines theism along with everything else. The believer cannot stand outside the brain to make the argument.
  5. Reliability is checked, not assumed. Darwin's "horrid doubt" about a monkey's mind is answered by the observation that truth-tracking is adaptive in general, and that where it is not (probability, the very large, the very small) we know, because we have built the tools that show us. The sophisticated version of this argument is Plantinga's Evolutionary Argument Against Naturalism; the crude version is the Transcendental Argument; the answer to all three is the same.

Sources

  • Lewis, C. S., Miracles (1947; rev. ed., 1960), ch. 3
  • Anscombe, G. E. M., "A Reply to Mr C. S. Lewis's Argument that 'Naturalism' is Self-Refuting", Socratic Digest 4 (1948)
  • Reppert, V., C. S. Lewis's Dangerous Idea (2003)
  • Haldane, J. B. S., Possible Worlds (1927)
  • Balfour, A., The Foundations of Belief (1895)
  • Beversluis, J., C. S. Lewis and the Search for Rational Religion (2nd ed., 2007)
  • Carrier, R., "Critical Review of Victor Reppert's Defense of the Argument from Reason", The Secular Web (2004)

Also see