This is Part 1 in a 3 part series on evolutionary theories of cognition. This part discusses C.S. Lewis’ Argument from Reason. Part 2 will examine Alvin Plantinga’s Argument from Proper Function and part 3 will cover Plantinga’s Evolutionary Argument Against Naturalism.
No matter how contentious an intellectual debate may appear, both parties agree on at least one thing. They both assume that rationality, if properly used, leads to true conclusions. The laws of identity, non-contradiction, and excluded middle, for example, accurately describe reality.1 If human perceptions about these basic truths were incorrect, then it would be impossible to reason to any conclusion.
Theists argue that this necessary presupposition is incompatible with a naturalistic worldview. If naturalism is true then rationality is not reliable, undercutting all beliefs including acceptance of naturalism itself. Arguments of this genre are coined “arguments from reason.”
C.S. Lewis’ Argument from Reason
C.S. Lewis advanced an argument from reason that can very generally be summarized as follows:
(1) If adherence to a worldview makes it impossible to believe that rational thinking is reliable, that worldview should be rejected.
(2) A naturalistic worldview makes it impossible to believe that rational thinking is reliable.
(3) Therefore, a naturalistic worldview should be rejected.2
Premise (1) is uncontroversial. “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.”3
Premise (2) is the heart of Lewis’ argument which he supports with a sub-argument:
(2.1) Rational thinking is reliable only if it is based upon recognizing ground-consequent relationships.
(2.2) If two things are related by cause-effect, they are not also related by ground-consequent.
(2.3) According to naturalism, all phenomena are explained only on a cause-effect basis.
(2.4) The category of “all” phenomena includes rational thinking.
(2.5) Naturalism requires that rational thinking be based upon cause-effect relationships rather than ground-consequent relationships.4
(2.6) Therefore, a naturalistic worldview makes it impossible to believe that rational thinking is reliable.5
Lewis’ argument hinges on his distinction between cause-effect and ground-consequent relationships.
We can say, ‘Grandfather is ill today because he ate lobster yesterday.’ We can also say, ‘Grandfather must be ill today because he hasn’t got up yet (and we know he is an invariably early riser when he is well).’ In the first sentence because indicates the relation of Cause and Effect: The eating made him ill. In the second, it indicates the relation of what logicians call Ground and Consequent. The old man’s late rising is not the cause of his disorder but the reason why we believe him to be disordered.6
Rationality depends upon premises being seen as grounds for a consequent conclusion (2.1). But if “causes fully account for a belief, then, since causes work inevitably, the belief would have had to arise whether it had grounds or not” (2.2).7 If naturalism is true8 “every event in Nature must be connected with previous events in the Cause and Effect relation” (2.3).9 Acts of thinking are “events in Nature” (2.4). Therefore, according to naturalism they also must be explained by previous events on a cause-effect basis (2.5).10 The conclusion (2.6) therefore follows from (2.1) and (2.5).11
Lewis’ argument has not been without its critics. Erik J. Wielenberg challenges Lewis’ premise that naturalism must explain rationality only on a cause-effect basis.12 He argues that because evolutionary theory predicts human reasoning will be incapable of explaining rationality, that outcome cannot be used as evidence against it.13
Weilenberg relies upon Colin McGinn’s “New Mysterianism.” According to McGinn, human intelligence “is an evolutionary contrivance, designed with purposes far removed from the solution of profound philosophical problems, and it is not terribly surprising if it lacks the tools to crack every problem.”14 Weilenberg claims the theist uses this same approach to answer the problem of evil by arguing a finite human mind should not be expected to fully comprehend the infinite divine mind.15
Weilenberg’s parallel, though, fails. The theistic argument against evil claims that strong non-propositional evidence for the existence of the theistic God overwhelms the evidence from evil against him.16 The alleged parallel is that non-propositional evidence for the existence of truth-guided rationality overwhelms the evidence from naturalism against it. The naturalist’s version, though, unlike the theist’s, contains “a double presupposition.” In claiming to believe that non-propositional evidence for accurate reasoning abilities counts as “evidence” at all, the naturalist must presuppose (1) that human belief-forming mechanisms are designed to promote the formation of accurate beliefs and (2) that these mechanisms do in fact generate true beliefs. Only then is the naturalist justified in trusting a belief in the non-propositional evidence for reliable rationality.17 But “the reflective naturalist will doubt both of these”18 because, as Lewis and Plantinga19 illustrate, a naturalistic worldview cannot support the conclusion that rationality promotes true beliefs, including a belief in non-propositional evidence.20
Some critics claim that creatures with reliable cognitive abilities hold a survival advantage over those whose reasoning is unreliable. Therefore, over time natural selection will lead reliable faculties to predominate society.21
First, “some creatures are able to survive and procreate without any beliefs whatsoever. What is required for survival is effective response to the environment, not accurate knowledge of that environment.”22
Second, the “mere presence of survival value does not guarantee that we really have a naturalistic explanation on our hands. The item possessing the survival value must be physically realizable.”23 Lewis never claimed natural selection could not promote the survival of accurate reasoning abilities once they existed but rather that naturalism has no way to account for their coming into being initially.24
Third, even if inaccurate rationality was wholly unfavorable toward survival, natural selection would not necessarily weed it out. The same gene may influence both a favorable and an unfavorable trait.25 The unfavorable trait survives despite its disadvantages because it is “linked” to a more advantageous one. Even if accurate reasoning abilities promote survival (and human cognitive abilities have proven over time to be favored by natural selection), that does not mean those abilities are reliable. Inaccurate abilities may have survived because they were linked to something more advantageous.
In response to Lewis, John Beversluis claims the act of drawing an inference is not a form of knowledge. Logical rules are true without any need for further justification as to why they are true.26
First, Beversluis is clearly mistaken that drawing an inference is not an act of knowing. When people reason “If p then q, p, therefore q,” they are not simply stating that it will hold true in the particular case before them. Rather they believe that this inference (modus ponens) will hold true in the future as well and in all possible worlds. This is clearly “knowledge” of reality.
Second, Beversluis confuses ontology with epistemology. He is correct that modus ponens is ontologically true without any need for further explanation. However, the key question is how people may know it to be true. That is a matter of epistemology. If naturalism is true, all events are the result of preceding efficient causes. The mental act of knowing modus ponens to be true in this and all possible worlds is no different.27
(Continued in Part 2)
1. While some eastern and new age worldviews attempt to reject the law of non-contradiction in favor of a dialectic approach, this is actually one of the major stumbling blocks for these worldviews. They must employ the law of non-contradiction in order to argue against it. In the end, these truths appear undeniable.↩
2. C.S. Lewis, “Miracles,” in The Complete C.S. Lewis Signature Classics, ed. Joseph Rutt (San Francisco: HarperCollins, 2002), 218-19.↩
3. Lewis, “Miracles,” 218.↩
4. This is derived from (2.2), (2.3) and (2.4).↩
5. This is derived from (2.1) and (2.5).↩
6. Lewis, “Miracles,” 219.↩
7. Lewis, “Miracles,” 219.↩
8. According to Lewis, “The Natural is what springs up, or comes forth, or arrives, or goes on, of its own accord: the given, what is there already: the spontaneous, the unintended, the unsolicited. What the Naturalist believes is that the ultimate Fact, the thing you can’t go behind, is a vast process in space and time which is going on of its own accord.” Lewis, “Miracles,” 214.↩
9. Lewis, “Miracles,” 219.↩
10. Lewis, “Miracles,” 219. Perhaps the naturalist could claim they are caused by electrical impulses in the brain.↩
11. The reasoning is as follows: (2.1) If A then B. (2.1a) If ~B then ~A (from (2.1) via transposition). (2.5) If C then ~B. (2.6) If C, then ~A (from (2.1a) and (2.5) via the law of syllogism).↩
12. Erik J. Wielenberg, God and the Reach of Reason: C.S. Lewis, David Hume, and Bertrand Russell (Cambridge: Cambridge University Press, 2008), 104.↩
13. Wielenberg, God and the Reach of Reason, 105.↩
14. Colin McGinn, The Mysterious Flame: Conscious Minds in a Material World (New York: Basic Books, 1999), 45.↩
15. Wielenberg, God and the Reach of Reason, 107-08. The theist argues that if an infinite God exists then he may have reasons for allowing suffering that the finite mind cannot comprehend.↩
16. For example, the theist could find strong evidence from the inner testimony of the Holy Spirit, or believe that “God has so created us that we have a tendency or disposition to see his hand in the world about us” and this disposition is so powerful that it overwhelms all competitors. Alvin Plantinga, “Is Belief in God Rationally Acceptable?” in Philosophy of Religion: A Reader and Guide, ed. William Lane Craig (New Brunswick, NJ: Rutgers University Press, 2002), 40-56.↩
17. This point was made by Alvin Plantinga in response to a similar argument raised against him by Timothy O’Connor. Alvin Plantinga, “Reply to Beilby’s Cohorts,” in Naturalism Defeated? Essays on Plantinga’s Evolutionary Argument Against Naturalism, ed. James Beilby (Ithaca: Cornell University Press, 2002), 238; Timothy O’Connor, “A House Divided Against Itself Cannot Stand: Plantinga on the Self-Defeat of Evolutionary Naturalism” in Naturalism Defeated? Essays on Plantinga’s Evolutionary Argument Against Naturalism, ed. James Beilby (Ithaca: Cornell University Press, 2002), 129-34.↩
18. Plantinga, “Reply to Beilby’s Cohorts,” 238.↩
19. The reasons supporting Plantinga’s argument will be explored more fully in the subsequent section of this paper discussing his “Evolutionary Argument Against Naturalism.”↩
20. Omar Mirza articulates an interesting twist on the parallel with the problem of evil. Mirza argues that theists contend God allows evil because he has morally sufficient reasons for doing so. Even under a theistic worldview, then, God could have morally sufficient reasons for allowing rational faculties to be unreliable. Omar Mirza, “The Evolutionary Argument Against Naturalism,” Philosophy Compass 6, no. 1 (2011): 84. Mirza overlooks the fact that Plantinga’s argument discusses defeaters on the basis of the “Probability Thesis;” i.e., that on the assumption of naturalism the probability of reliable rationality is low or inscrutable. It is not enough to argue that given theism God could allow for unreliable faculties. It must be probable that he would do so. Mirza never defends why it is probable, not merely possible, that God would allow this to occur.↩
21. See, e.g., Theodore Drange, “Several Unsuccessful Formulations of the Argument from Reason: A Response to Victor Reppert,” Philosophia Christi 5, no. 1 (2003): 35-52.↩
22. Victor Reppert, C.S. Lewis’s Dangerous Idea: A Philosophical Defense of Lewis’s Argument From Reason (Downers Grove, IL: IVP Academic, 2003), 100.↩
23. Reppert, C.S. Lewis’s Dangerous Idea, 97.↩
24. Erik J. Weilenberg attempts a similar argument. He claims that whether naturalism is compatible with reliable reasoning abilities depends upon whether the initial organisms were reliable cognizers. “Evolutionary forces operating on organisms that are reliable cognizers would be much more likely to produce reliable cognizers than would those same forces operating on unreliable cognizers.” Erik J. Weilenberg, “How to be an Alethically Rational Naturalist, in Synthese 131, no. 1 (April 2002), 91. However, Weilenberg fails to recognize that he has merely moved the dilemma back a step. He must now explain how those “initial organisms” were able to draw true rational conclusions, and this is precisely what a naturalistic worldview does not allow.↩
25. This concept is known as “pleiotropy.”↩
26. John Beversluis, C.S. Lewis and the Search for Rational Religion (Amherst, NY: Prometheus, 2007), 172.↩
27. Beversluis also argues that from “the fact that there is a cause for every event, including mental events, it does not follow that a person cannot also have a reason for what she believes.” Beversluis, C.S. Lewis and the Search for Rational Religion, 166. He uses the example of Beethoven’s composing his Fifth Symphony to illustrate that there can be multiple types of explanations for the same event. In response to the question, “Why did Beethoven compose this symphony?” a psychologist would articulate a different answer from a musicologist, but that does not make either answer incorrect. The problem with Beversluis’ reasoning is that even if the same event can have both a cause-effect explanation and a ground-consequent explanation (something which Lewis denied but which can be granted for the sake of argument), theism allows for this type of dual causation whereas naturalism does not. Under theism, it is possible that God instilled humanity with a physical makeup that would cause people (in a cause-effect relationship) to reason to true conclusions about the world (ground-consequent). But the essence of naturalism is that it can only give cause-effect explanations, thus it can never produce the type of dual causation Beversluis proposes.↩