PhilosoPhia Christi Vol. 19, No. 2 © 2017 The Argument from Reason, and Mental Causal Drainage A Reply to Peter van Inwagen braNDoN rickabaugh Department of Philosophy Baylor University brandon_rickabaugh@baylor.edu toDD buras Department of Philosophy Baylor University todd_buras@baylor.edu 1. Introduction Naturalism faces numerous problems. One family of objections that has gained more recent attention falls under the banner of the argument from reason. Contemporary versions of the argument are commonly inspired by the work of C. S. Lewis.1 Peter van Inwagen, however, is not so impressed and has recently raised a significant objection.2 According to van Inwagen, Lewis never defended the central premise of his argument from reason. Even worse, van Inwagen argues that Lewis's central premise is false. If van Inwagen is right, a significant gap in Lewis's argument must be filled and may not even be fillable. Indeed, the problem van Inwagen raises may also apply to other versions of the argument from reason. aBstraCt: According to Peter van Inwagen, C. S. Lewis failed in his attempt to undermine naturalism with his argument from reason. According to van Inwagen, Lewis provides no justification for his central premise, that naturalism is inconsistent with holding beliefs for reasons. What is worse, van Inwagen argues that the main premise in Lewis's argument from reason is false. We argue that it is not false. The defender of Lewis's argument can make use of the problem of mental causal drainage, a long-standing issue in philosophy of mind, to show how van Inwagen's objection fails. 1. C. S. Lewis, Miracles: A Preliminary Study, rev. ed. (1960; New York: Harper Collins, 1996), ch. 3. 2. Peter van Inwagen, "C. S. Lewis's Argument against Naturalism," The Chronicle of the Oxford University C. S. Lewis Society 7 (2010): 2–12; reprinted in Res Philosophica 90 (2013): 113–24. All references are to the Res Philosophica version. 382 PhilosoPhia Christi Others have argued that van Inwagen's objection fails by ignoring essential elements of Lewis's argument.3 We are less interested in defending Lewis than with strengthening the argument from reason in such a way as to avoid van Inwagen's objection. We contend that the defender of the argument from reason has a promising argument-the problem of causal drainage-to fill the gap van Inwagen identifies. In what follows we explain van Inwagen's exposition of Lewis's argument. We then introduce and analyze van Inwagen's objection to Lewis's argument from reason. In the final section, we offer our argument against van Inwagen's objection, and raise and respond to likely replies. 2. The Argument from Reason The argument from reason is actually a family of arguments each of which argues from certain features of cognition to either the demise of determinism, physicalism, or naturalism or for the existence of the soul, and or the existence of God. For example, James Pratt states the core issue as follows. To say that a thought is even in a minute degree a co-cause of the following thought would be to wreck Materialism. In the process known as reasoning, therefore, it is a mistake to suppose that consciousness of logical relations has anything whatever to do with the result. It is not logical necessity but mechanical necessity that squeezes out our so-called reasoning conclusions.4 More recently, E. J. Lowe, makes the same point regarding determinism when he writes, If what they [determinists] say is true, then the movements of their minds that have led them to say it are simply consequences of certain causal laws governing those movements. Hence, these movements of their minds may at most replicate valid reasoning but do not and cannot constitute it. Consequently, their belief in the conclusion-that we have no rational free will-is not a rationally held belief.5 Common among all versions of the argument is that reason is a problem for views such as determinism, naturalism, or physicalism. Although generally associated with C. S. Lewis, versions of this argument can be found in 3. See, e.g., Marcel Sarot, "The Cardinal Difficulty for Naturalism: C. S. Lewis' Argument Reconsidered in Light of Peter van Inwagen's Critique," Journal of Inklings Studies 1 (2011): 41–53. 4. James Pratt, Matter and Spirit (1922; London: Forgotten Books, 2012), 19. 5. E. J. Lowe, "Substance Causation, Powers, and Human Ontology," in Mental Causation and Ontology, ed. S. C. Gibb, E. J. Lowe, and R. D. Ingthorsson (New York: Oxford University Press), 171. BranDon riCkaBaugh anD toDD Buras 383 the works of Augustine, Anselm, Descartes, and Kant.6 Versions of the argument just before Lewis were made by Arthur Balfour, and J. B. Pratt.7 The argument was revived by A. E. Taylor, and received significant attention by those such as Eric Mascall, Norman Malcolm, J. R. Lucas, and A. C. Ewing, among many others.8 More recently, versions of this argument have been developed and defended by Noam Chomsky, William Hasker, J. P. Moreland, Ian Markham, Alvin Plantinga, Darek Barefoot, Angus Menuge, Michael Rea, E. J. Lowe, Todd Buras, and John DePoe.9 No doubt, Victor Reppert 6. In what follows we are indebted to Victor Reppert's historical work on the argument from reason. See Victor Reppert, C. S. Lewis's Dangerous Idea: In Defense of the Argument from Reason (Downers Grove, IL: InterVarsity, 2003). We have done the research to include references to the specific passages of these works. See, Augustine, On Free Choice of the Will, trans. Thomas Williams (Indianapolis, IN: Hackett, 1993), bk. 2.6, and 10, 40–1, and 49–50; Anselm, Monologion, ch. 18; Rene Descartes, Meditations on First Philosophy, meditations 3 and 4; and Henry E. Allison, "Kant's Refutation of Materialism," The Monist 79 (1989): 190–209. 7. Arthur Balfour, The Foundations of Belief: Notes Introductory to the Study of Theology, 8th ed. (New York: Longmans, 1906); and Pratt, Matter and Spirit, 18–21. 8. A. E. Taylor, "Freedom and Personality," Philosophy 14 (1939): 259–80; "Freedom and Personality Again," Philosophy 17 (1942): 26–37; Eric Mascall, Christian Theology and Natural Science: Some Questions in Their Relations (New York: Longmans, 1956), 214–16; Norman Malcolm, "The Conceivability of Mechanism," Philosophical Review 77 (1968): 45–72; J. R. Lucas, Freedom of the Will (New York: Oxford University Press, 1970), 114–16; A. C. Ewing, Value and Reality: The Philosophical Case for Theism (London: George Allen and Unwin, 1973), 76–8. For others, see, e.g., Paul Weiss, Nature and Man (Carbondale, IL: Southern Illinois University Press, 1947), 23–6; E. L. Mascall, Christian Theology and Natural Science (London: Longmans, 1956), 212–19; A. C. MacIntyre, "Determinism," Mind 66 (1957): 28–41; Lionel Kenner, "Causality, Determinism and Freedom of the Will," Philosophy 29 (1964): 233– 48; Warner Wick, "Truth's Debt to Freedom," Mind 73 (1964): 527–37; Sir Malcolm Knox, Action (London: Allen and Unwin, 1968), 68–80; James N. Jordan, "Determinism's Dilemma," Review of Metaphysics 23 (1969): 48–66; Joseph M. Boyle, Germain Grisez, and Olaf Tollefsen, "Determinism, Freedom, and Self-Referential Arguments," The Review of Metaphysics 26 (1) (1972): 3–37. 9. See, Noam Chomsky, "The Case Against B. F. Skinner," New York Review of Books, December 30, 1971, 20–6; William Hasker, "Transcendental Refutation of Determinism," Southern Journal of Philosophy 9 (1973): 175–83; and The Emergent Self (Ithaca, NY: Cornell University Press, 1999), 64–74; J. P. Moreland, Scaling the Secular City: A Defense of Christianity (Grand Rapids, MI: Baker Books, 1987), 90–6; The Recalcitrant Imago Dei: Human Persons and the Failure of Naturalism (London: SCM, 2009), 67–103; Ian Markham, Truth and the Reality of God: An Essay in Natural Theology (Edinburgh: T&T Clark, 1998); Alvin Plantinga, Warrant and Proper Function (New York: Oxford University Press, 1993), ch. 12; and Warranted Christian Belief (New York: Oxford University Press, 2000), 227–40, 281–4, 350–1; Darek Barefoot, "A Response to Nicholas Tattersall's 'A Critique of Miracles by C. S. Lewis'" (2001), http:// www.secweb.org/index.aspx?action=viewAsset&id=89; and "A Response to Richard Carrier's Review of C. S. Lewis's Dangerous Idea" (2007), http://www.infidels.org/library/modern/ darek_barefoot/dangerous.html; Angus Menuge, Agents under Fire: Materialism and the Rationality of Science (Lanham, MD: Rowman and Littlefield, 2004), ch. 6; Michael Rea, World without Design: The Ontological Consequences of Naturalism (New York: Oxford University Press, 2002), 177–93; E. J. Lowe, Personal Agency: The Metaphysics of Mind and Action (New York: Oxford University Press, 2008), 179–98; Todd Buras, "On the Failures of Naturalism," Review and Expositor 111 (2014): 259–73; and John DePoe, "The Self-Defeat of Naturalism: A Critical Comparison of Alvin Plantinga and C. S. Lewis," Christian Scholars Review 44 (2014): 9–26. 384 PhilosoPhia Christi has done the most detailed work on the argument from reason.10 Even atheist Thomas Nagel argues that reason is a problem for materialism.11 Given that our aim is to meet van Inwagen's objection directly, we follow his statement or rather his restatement of Lewis's argument from reason. Consequently, our conclusions may be limited to those arguments that closely track with Lewis's. 3. Lewis's Argument from Reason 3.1. Naturalism and Complete Explanation To begin with we must be clear about what naturalism is and what it entails. Van Inwagen understands Lewis's description of naturalism as follows: Nature (the cosmos, the physical universe) is all there is or was or ever will be: everything that exists is a part of Nature. All the parts of Nature-from sub-atomic particles to clusters of galaxies-are governed by the same set of exceptionless deterministic laws.12 Van Inwagen broadens the notion of naturalism to allow for both strict deterministic laws and probabilistic laws. However, even if nonrational states or subpersonal processes establish the probability of my having a specific thought, it is not necessarily the case or even very likely that my thought has a rational or personal cause. Hence, even supposing that Lewis focused on deterministic versions of naturalism, it is not plausible that merely appealing to indeterminism will help.13 Indeterminism does not entail rational or personal causation. For that matter neither does libertarian free will. What we need, in our estimation, is personal or agent causation. A few details must be clarified before we move on.14 The term "naturalism" has been used in various ways.15 While, van Inwagen has stated natu10. See, e.g., Reppert, C. S. Lewis's Dangerous Idea; "The Argument from Reason and Hume's Legacy," in In Defense of Natural Theology, ed. J. Sennett and D. Groothuis (Downers Grove, IL: InterVarsity, 2005), 253–70); "Miracles: C. S. Lewis's Critique of Naturalism," in C. S. Lewis: Life Works and Legacy, vol. 3, Apologist, Philosopher, Theologian, ed. Bruce L. Edwards (Westport, CT: Praeger, 2007), 153–81; and "The Argument from Reason," in The Blackwell Companion to Natural Theology, ed. William Lane Craig and J. P. Moreland (Oxford: Blackwell, 2009), 344–90. Although we have a number of reservations about it, the recent book by Jim Slagle is worth noting: The Epistemological Skyhook: Determinism, Naturalism, and Self-Defeat (New York: Routledge, 2016). 11. Thomas Nagel, Mind and Cosmos: Why the Materialist Neo-Darwinian Concept of Nature Is Almost Certainly False (New York: Oxford University Press, 2012), esp. ch. 4. 12. Van Inwagen, "C. S. Lewis's Argument against Naturalism," 117. 13. We are grateful to an anonymous reviewer for this point. 14. The following discussion relies on the treatment in Todd Buras, "On the Failures of Naturalism," 260–2. 15. The ambiguity of the term has been noted by virtually everyone writing on the subject. See, e.g., Roy Wood Sellars, Evolutionary Naturalism (Chicago: Open Court, 1922), vii; and BranDon riCkaBaugh anD toDD Buras 385 ralism as a claim about what there is, naturalism also entails a claim about explanation. Realism about explanation is widely accepted, and entails the existence of entities posited by our best explanations. The principle of parsimony requires that we accept the existence of only those entities posited by our best explanations. A claim about what there is entails a claim about a certain mode of explanation, and vice versa. The distinctively scientific mode of explanation is subpersonal and mechanistic.16 To give a mechanistic explanation of some phenomena (for example, change in location) is to cite a property of an object (for example, the mass of a body) together with a natural law (for example, Newton's inverse-square law) describing how things with that property regularly behave. Such laws describe the most general patterns of variation in nature, based on the inherent tendencies of things. Mechanistic explanations thus tell us what we can expect to happen automatically (deterministically or probabilistically) and, as it were, of its own accord. That is, whether prior events strictly necessitate or fix the chances of a future event, still that event is the automatic result of nonrational causes. Deterministic laws predict a fixed outcome for phenomena that fall under their jurisdiction. Probabilistic laws, by contrast, assign a probability to all possible outcomes, and leave it to chance to resolve which comes to pass. Mechanistic explanations thus tell us that some phenomenon occurs because the state of the universe and the laws of nature necessitate it or make it somewhat likely. Here is our point: the central idea of naturalism (at least with respect to explanation) is that mechanistic explanation is in principle complete, that is, sufficient to explain everything that needs explaining.17 Barry Stroud, "The Charm of Naturalism," in Naturalism in Question, ed. Mario De Caro and David Macarthur (Cambridge, MA: Harvard University Press, 2004), 22. Both sources are discussed by Stewart Goetz and Charles Taliaferro, Naturalism (Grand Rapids, MI: Eerdmans, 2008), 6–7. See also, David Papineau, "Naturalism," in Stanford Encyclopedia of Philosophy, ed. Edward N. Zalta, http://plato.stanford.edu/archives/spr2009/entried/naturalism. For important surveys of positions that have flown under the banner of naturalism in the twentieth century, see Michael C. Rea, World without Design, 21–49; and Philip Kitcher, "The Naturalist's Return," Philosophical Review 101 (1992): 53–114. 16. The account of scientific explanation in this paragraph and the next follows Richard Swinburne, The Existence of God, 2nd ed. (New York: Oxford University Press, 2004), 26–35, which is in turn based on the classic exposition in C. G. Hempel and P. Oppenheim, "Studies in the Logic of Explanation," Philosophy of Science 14 (1948): 135–75. 17. This account of naturalism follows Richard Swinburne's treatment of "materialism" in Is There a God?, rev. ed. (New York: Oxford University Press, 2010), 36–37. It is also draws from C. Stephen Layman, Letters to a Doubting Thomas (New York: Oxford University Press, 2007), 16–17, and from Peter Forrest, God without the Supernatural: A Defense of Scientific Theism (Ithaca, NY: Cornell University Press, 1996), 88–9. Because of the connections between this claim of explanatory sufficiency and the ontological claims discussed in this section, the account is also consistent with that defended by David Papineau in Philosophical Naturalism (Malden, MA: Blackwell, 1993), and in "Naturalism." See also the discussion of "core ontological naturalism" in Paul K. Moser and David Yandell, "Farewell to Philosophical Naturalism," in Naturalism: A Critical Analysis, ed. William Lane Craig and J. P. Moreland (New York: Rout386 PhilosoPhia Christi Of course, this does not entail that naturalism must explain everything. Claiming that mechanistic explanation is in principle complete is also not the same as claiming simply that mechanistic explanation is complete. Naturalists are therefore also free to concede that we do not yet have a properly mechanistic explanation for all causal difference-makers. The defining claim of naturalism requires only that there be no principled barrier to such explanations. 3.2. Naturalism and Anti-Rationalism The core of Lewis's argument, says van Inwagen, is the conditional claim that if naturalism is true then our thoughts are governed by "the same set of exceptionless deterministic laws that govern the behavior of falling apples and beams of light and neurons and clouds of intersidereal gas."18 The claim is that naturalism entails mechanistic explanation, as we argued above. From this it follows that naturalism implies what van Inwagen calls "antirationalism," the thesis that none of our beliefs are based on reasoning; reasoning plays no role in the explanation of why anyone holds any belief.19 Consequently, if naturalism is true, then none of our beliefs is based on reasoning, including our belief in naturalism.20 In light of this we should reject naturalism for the same reasons we should reject antirationalism: we quite literally have no reason to believe it is true.21 3.3. Explanation: Mechanistic and Rational Lewis distinguishes between mental states (for example, beliefs) that are produced by cause-effect relations and mental states that are brought about by ground-consequent relations.22 To see the difference, consider two types of answers we can give to the question, "Why do you believe that p?" An answer can invoke one of the following notions of explanation. Mechanistic Explanation: You explain your belief by explaining its cause: your belief that p is the effect of some mechanical, nonmental causal story. ledge, 2000), 4; and in Graham Oppy, The Best Argument against God (New York: Palgrave Macmillan, 2013), 6–7. 18. Van Inwagen, "C. S. Lewis's Argument against Naturalism," 117. 19. Ibid. 20. Ibid. 21. Others makes the same point regarding determinism. See, e.g., Lowe, "Substance Causation, Powers, and Human Ontology," 171; and Malcolm, "The Conceivability of Mechanism." 22. Lewis introduces these terms and distinction in, Miracles, 22–3. For the sake of readability, we substitute Lewis's terms of cause-effect because and ground-consequent because with mechanistic explanation and rational explanation, respectively. BranDon riCkaBaugh anD toDD Buras 387 Rational Explanation: You explain your belief by explaining its ground: your belief that p is rationally based on the intentional content of prior beliefs, and certain logical relations among those beliefs.23 More must be said to clarify what we mean by rational explanation. The claim that some belief b is based on reasons purports to explain an action- the mental action of accepting or forming b. Although this is a causal explanation it is not a mechanistic explanation, but is a rational explanation. The suggestion is that a belief b is accepted because an agent S: (i) intends to accept the truth; (ii) sees that certain propositions are true;24 and (iii) sees that the truth of these propositions supports the truth of the propositional content of b. The rational explanation for an agent's belief is further understood as a causal claim, and has been since Donald Davidson made the following point.25 An agent may have a reason to perform some action and actually perform the action, but not do so because of the reason she has. In order to perform the action because of a reason the reason must be part of the causal explanation of the action. You may have a reason (in the form of a convincing piece of evidence) to believe, say, that everyone is out to get you; and yet you might believe that everyone is out to get you not because of the evidence you have, but because you are afflicted with psychotic paranoia. Unless your reason is involved in the production of the belief,26 it seems fair to say that you did not believe based on the reason. Another way of understanding the distinction between mechanistic explanation and rational explanation is to understand that rational explanation 23. E.g., your belief that Alyssia is taller than Sawyer could be grounded in the intentional content of the belief that Alyssia is taller than Laura and Laura is taller than Sawyer along with the implicit or explicit belief in the transitivity of identity. 24. By "seeing" we mean seeing in the sense of Edmund Husserl's "eidetic intuition" or intellectual seeing. For an internalist evidentialist account of this see Trent Dougherty, "Principles of Inferential Justification," in Intellectual Assurance: Essays on Traditional Epistemic Internalism, ed. Brett Coppenger and Michael Bergmann (New York: Oxford University Press, 2016), 128–43; as well as, Michael Huemer, "Inferential Appearances," in Intellectual Assurance, 144–60. 25. Donald Davidson, "Actions, Reasons, and Causes," Journal of Philosophy 60 (1963): 685–700. On the history of causalism in the twentieth century, see Giuseppina D'Oro and Constantine Sandis, "From Anti-Causalism to Causalism and Back: A History of the Reasons/ Causes Debate," in Reasons and Causes: Causalism and Anti-Causalism in the Philosophy of Action, ed. D'Oro and Sandis (London: Palgrave McMillan, 2013). 26. Such cases involve causal deviance where a reason figures in the causal etiology of a conclusion, although it does not participate in the right way. E.g., suppose that a neuroscientist can correlate your brain states with certain intentional states. In doing so she causes you to believe F as well as "if F then Y." Suppose further that you are too lethargic to draw the proper conclusion that Y. However, she stimulates your brain so that you believe that Y. In such a case, your reasons cause you to believe that Y, but not in the right way. The neuroscientist reasoned to the conclusion that Y, but you did not. We are grateful to an anonymous reviewer for pointing this out to us. 388 PhilosoPhia Christi is a subclass of what Richard Swinburne calls personal explanation.27 Personal explanations make no appeal to the changes dictated by the state of the universe together with deterministic or probabilistic laws. Instead, they cite agents with basic powers and the intention to exercise those powers. Personal explanations tell us that something happens on purpose, that is, because an agent with the power to bring it about meant for it to occur. As Swinburne notes, personal explanation is a pervasive feature of our ordinary understanding of mundane phenomena. We offer and accept personal explanations not only for changes in our own thoughts (as when one calls something to mind in order to contemplate it), but also of changes in the physical world (as when one waves an arm to send a signal). What personal explanation adds to rational explanation is that an agent acts in virtue of her reasons. That a reason is part of the causal explanation of an action is not enough, as one would only be acting in accordance with reason (acting reasonably), which is distinct from acting rationally. "To be rational, says Lowe, "it much be done for a reason which the agent freely chooses to act upon . . . ."28 Accordingly, the reason for which a rational agent acts is not just some reason, but the reason she chooses to act upon. It is the agent herself, not her mental states or brain states, that brings about her free mental action. There are no subpersonal mechanisms or process doing the work.29 The agent provides a personal explanation, not reducible to anything else, for rational action. Although we will talk of mental states and rational explanations, on our view it is the causal power of agents that put mental states and rationality to work. So, when we refer to mental states and reasons as causes, we consider the agent is first cause. 3.4. Exclusion: The Core of Lewis's Argument The core of Lewis's argument from reason is that if the explanation for our beliefs is in terms of a complete mechanistic explanation, then our beliefs cannot be explained by a rational explanation. That is, Lewis's argument hinges on the truth of the following principle. exClusion: For any belief b, if b has a complete mechanistic explanation then b cannot also have any rational explanation. 27. See Swinburne, The Existence of God, 35–8. 28. Lowe, Personal Agency, 182. 29. An interesting implication lurking in the background is that externalism about justification, which reduces justification to subpersonal processes makes physicalism in the philosophy of mind more probable than internalism about justification, which seems to make mind-body dualism more probable. See Brandon Rickabaugh and Trent Dougherty, "Epistemology, Mind, and Hard Choices: Externalism or Dualism, but Not Both," forthcoming (preprint available at http://www.brandonrickabaugh.com). BranDon riCkaBaugh anD toDD Buras 389 It is important to understand the work that a complete mechanistic explanation is doing here. Recall that naturalism entails a claim about explanation, that is, naturalism is complete or sufficient to explain everything that needs explaining. With respect to belief, naturalism entails that any belief b, if it is to be explained, will in principle be given a sufficient mechanistic explanation, such that nonmechanistic explanations are eliminable. That is, if mechanistic explanation is complete, personal explanations are eliminable. Swinburne thus takes a commitment to the eliminability of personal explanation to be definitive of the view we are calling naturalism, as does Ted Honderich and Graham Oppy.30 Furthermore, exClusion follows from the fact that mechanistic explanations do not depend on either intentional content or teleology. However, an agent's rational action is explained by their reasoning, which requires intentional contents with the goal of finding or proving a conclusion. So, given that a complete mechanistic explanation makes content and teleology unnecessary to explain any aspect of reality, then rational or personal explanation is redundant. However, we argue below, that if naturalism is true, then rational or personal causes do not even exist. In summary, Lewis's argument from reason aims to show that if naturalism is true, then any belief one holds will in principle be given a complete mechanistic explanation, such that all rational explanation is eliminated. This argument defends the following conditional: if naturalism is true, then every event has a complete mechanistic explanation, and if every event has a complete mechanistic explanation, then any other explanation will have no work to do. This argument is made in part by defending the claim that exClusion follows from naturalism. In the final section, we defend this claim. 4. Van Inwagen's Rejection of Exclusion Van Inwagen recognizes that exClusion is essential to Lewis's argument.31 Accordingly, his objection is rightly aimed at exClusion. So, why does he think exClusion is false? Suppose that naturalism is true. Human persons are purely physical things, which, among other things, have beliefs (as naturalists understand them). Suppose that Phoebe, a human person, believes that Lewis fought in WWI. Why does Phoebe hold this belief? It seems to van Inwagen that the following is a correct answer: "She believes that because [mechanistic explanation] she believes that it says so in the C. S. Lewis book, Surprised by Joy, and she also believes that no one includes eas30. Swinburne, Is There a God?, 36 (his name for the view is materialism). Ted Honderich, How Free Are You?, 2nd ed. (New York: Oxford University Press, 1993). For a discussion of Honderich's point as it relates to the argument from reason, see Goetz and Taliaferro, Naturalism, 96–103. Oppy, The Best Argument against God, 6–7. 31. Van Inwagen, "C. S. Lewis's Argument against Naturalism," 119. 390 PhilosoPhia Christi ily detectable falsehoods in an autobiography."32 Van Inwagen points out that given naturalism the following must be true:33 (1) Phoebe believes that Lewis fought in the First World War. (2) Phoebe believes that Lewis stated in Surprised by Joy that he had fought in the First World War. (3) Phoebe believes that no one includes easily detectable falsehoods in an autobiography. Given naturalism, these three facts, says van Inwagen, are related such that the first two mechanistically cause the third.34 In the mechanistic sense, these two beliefs are drilled into her, as it were, by teachers in her past. These three facts mechanistically cause Phoebe to believe that Lewis fought in WWI. However, according to van Inwagen, this mechanistic explanation does not exclude Phoebe from giving the following first-person rational explanation. "I believe that because [rational explanation] Lewis states in Surprised by Joy that he fought in the First World War, and no one includes easily detectable falsehoods in an autobiography."35 According to van Inwagen we have no good reason to suppose that the third-person mechanistic explanation precludes the first-person rational explanation.36 Moreover, according to van Inwagen, the fact that Phoebe's having this belief was mechanistically caused by the universe having been in such-and-such a state millions of years ago does not exclude a rational explanation. Hence, exClusion is false. In order to explain this, van Inwagen makes use of a distinction between a remote cause and a proximate cause. According to van Inwagen, a remote cause x produces a distant effect y through a proximate cause z of y.37 In the case of Phoebe, the remote cause of Phoebe's belief that Lewis fought in WWI-the fact about the state of the universe long ago-causes the fact that Phoebe believes that Lewis fought in WWI. However, the remote cause will cause Phoebe's belief only through Phoebe's present-day belief facts, which are proximate causes of her belief. Remote causes, according to van Inwagen, provide third-person mechanistic explanation, while proximate causes provide first-person rational explanations. Accordingly, two types of causes, and thereby the two types of explanations, work together. From this van Inwagen concludes that Lewis has not shown us that a belief fact that has a complete mechanistic explanation cannot also have a complete rational explanation. He explains, "For all Lewis has shown, Phoebe's answer to the question, 'Why do you believe that Lewis fought in the First World War?' may be correct even if the fact that she has that belief is 32. Ibid., 121. 33. Ibid. 34. Ibid. 35. Ibid. 36. Ibid. 37. Ibid. BranDon riCkaBaugh anD toDD Buras 391 an inevitable consequence of facts about the state of the physical universe billions of years ago."38 If van Inwagen is correct, then this counterexample reveals a significant gap in Lewis's argument from reason. Moreover, his counterexample with Phoebe shows that this gap will be unfillable because what would fill the gap, exClusion, is false. An individual's belief (Phoebe's belief that Lewis fought in WWI) has both a complete mechanistic explanation as well as a rational explanation. But is this truly the case? 5. Filling the Gap: The Problem of Mental Causal Drainage Contrary to what van Inwagen claims, there are compelling reasons to think that third-personal mechanistic explanations exclude first-personal rational explanations as explanation. Jaegwon Kim, for example, has spent much of his career defending what he calls the supervenience or exclusion argument. If physicalism is true, argues Kim, then even if mental states supervene on or emerge from physical base states in the brain, the physical base states preempt or exclude any additional causal contribution by the supervenient or emergent mental states.39 Physicalism embraces the thesis that all physical effects have sufficient physical causes. Given overdetermination, that no physical effects are caused twice by distinct physical and mental causes, it follows that there cannot be any mental causation.40 That is, the complete mechanistic explanation and the physical level excludes any mental explanation. Likewise, John Searle argues in more than one place that if a non-Humean agent's libertarian free will is not the deciding factor in drawing a conclusion, then such an agent does not reason to a conclusion. One reason Searle offers is that the logical form of mechanistic explanations and personal or rational explanation are disparate. From our first-person conscious experience, we are aware of how our reasons for acting provide an explanation for our free actions, including reasoning.41 Moreover, these personal explanations are often complete explanations as no additional explanation 38. Ibid., 122. 39. We find the most powerful version of this argument stated in terms of a powers ontology. See, Timothy O'Connor and John Ross Churchill, "Is Non-reductive Physicalism Viable within a Causal Powers Metaphysic?," in Emergence in Mind, ed. Graham Macdonald and Cynthia Macdonald (New York: Oxford University Press, 2010), 43–60. 40. See, e.g., Jaegwon Kim, Physicalism, or Something Near Enough (Princeton, NJ: Princeton University Press, 2005), ch. 2. 41. For an additional argument for the necessity of the first-person perspective for rationality see Jaegwon Kim, "Reasons and the First Person," in Human Action, Deliberation and Causation, ed. J. A. M. Bransen and S. E. Cuypers, 67–87 (Dordrecht: Kluwer Academic, 1998); reprinted in Jaegwon Kim, Essays in the Metaphysics of Mind, 105–24 (New York: Oxford University Press, 2010). 392 PhilosoPhia Christi is required to explain what we have done. However, these personal or rational explanations have a logical form quite different from mechanistic explanations. Mechanistic explanation is of the logical form A caused B, while personal or rational explanation is of the logical form a rational self S performed act A, and in performing A, S acted on reason R. The form of the explanation is not to give causally sufficient conditions, but to cite the reason(s) for which the agent acted. From this Searle concludes that such explanations require postulating a non-Humean self.42 For our purposes, it is enough to show that mechanistic explanations exclude personal explanation. To clarify, there is a strong and weak understanding of van Inwagen's objection to Lewis's argument from reason. According to the weak objection, van Inwagen argues that Lewis failed to give an argument for exClusion. To support this, the Phoebe counterexample is an illustration of how Lewis does not defend exClusion. Alternatively, according to the strong objection, van Inwagen argues that exClusion is false. On this reading, the case of Phoebe is a counterexample that shows exClusion to be false. In this section, we offer a principled defense of exClusion that is not subject to van Inwagen's counterexample, thereby responding to both the weak and strong readings of van Inwagen's objection. We argue that if naturalism is true, then complete mechanistic explanations do in fact exclude personal, rational explanations. We argue for this by way of the problem of causal drainage. 5.1. Not Token, But Type, Plus Dependency Before introducing our main response to van Inwagen, a preliminary argument should be made. Our reply makes use of a particular picture of brain states and mental states. A naturalist might block this picture by appealing to identity theory. We want to briefly explain why this way out of the presupposition of our argument fails. Theories that identify mental and physical states, come in type or token varieties. If one adopts the type identity theory, then the property of having a mental content (the belief that Lewis fought in WWI), is the same property, for example, as having a c-fiber firing. Philosophers largely reject type identity theory in virtue of the multiple realizability of mental states. In the 1970s, Hilary Putnam and Jerry Fodor introduced and defended an argument against the type identity theory that has persuaded most to abandon type identity physicalism: the multiple realizability argument.43 What the multiple 42. See John R Searle, Freedom and Neurobiology: Reflections on Free Will, Language, and Political Power (New York, NY: Columbia University Press, 2007), 52–5. For a more robust defense of this argument see John R. Searle, Rationality in Action (Cambridge, MA: MIT Press, 2001), esp. ch. 4. 43. Hilary Putnam, "Psychological Predicates," in Art, Mind, and Religion, ed. W. H. Capitan and D. D. Merrill (Pittsburgh: University of Pittsburgh Press, 1967), 37–48; reprinted and reBranDon riCkaBaugh anD toDD Buras 393 realizability arguments show is that it is implausible that a mental state of a certain sort, say pain, is identical with a certain type of neural activity, say a c-fiber firing. It is conceivable, perhaps even empirically verifiable, that creatures of this planet or perhaps others experience pain although they have radically different neural states than ours. These creatures could experience pain without having any c-fibers at all. Hence, pain is not identical to any specific neural type, but is rather realizable by multiple neural types. Hence, type identity theory is widely taken to be false.44 Perhaps then one might opt for a token identity theory, according to which everything that instantiates any property at all instantiates physical properties.45 The standard identity view, especially among naturalists, is token identity supplemented with a dependence claim. The dependence claim is standardly expressed in terms of supervenience according to which two possible worlds that are alike with respect to physical properties will be alike with respect to all properties. Stated differently, the nonphysical properties of things are dependent upon or fixed by the physical properties. No change in the mental without a change in the physical.46 Given that our main argument in the following section applies to this supervenience picture, consider our argument there as addressing the popular naturalist token identity plus supervenience view just mentioned. titled as "The Nature of Mental States," in Hilary Putnam, Mind, Language, and Reality: Philosophical Papers, vol. 2 (New York: Cambridge University Press, 1975), 429–40. See also, Jerry A. Fodor, "Special Sciences, or the Disunity of Science as a Working Hypothesis," Synthese 28 (1974): 97–115; reprinted in Philosophy of Mind: Classical and Contemporary Readings, ed. David J. Chalmers (New York: Oxford University Press, 2002), 126–34; and Jerry Fodor, "The Nature of Mental States," in Mind, Language, and Reality: Philosophical Papers, vol. 2 (New York: Cambridge University Press, 1975). 44. For more recent reevaluations of the argument, see Jaegwon Kim, "Multiple Realization and the Metaphysics of Reduction," Philosophy and Phenomenological Research 52 (1992): 1–26; reprinted in Philosophy of Mind: Classical and Contemporary Readings, ed. David J. Chalmers, 135–49; and William Bechtel and Jennifer Mundale, "Multiple Realizability Revisited: Linking Cognitive and Neural States," Philosophy of Science 66 (1999): 175–207. For an extensive discussion of the multiple realizability argument see Lawrence Shapiro, The Mind Incarnate (Cambridge, MA: MIT Press, 2004); and Lawrence A. Shapiro and Thomas W. Polger, "Identity, Variability, and Multiple Realization in the Special Sciences," in New Perspectives on Type Identity: The Mental and the Physical, ed. Christopher Hill and Simone Gozzano (New York: Cambridge University Press, 2012), 264–87. 45. See, e.g., David Papineau, "Causation Is Macroscopic but Not Irreducible," in Mental Causation and Ontology, ed. S. C. Gibb, E. J. Lowe, and R. D. Ingthorsson (New York: Oxford University Press, 2013), 150–1. 46. For an alternative argument that naturalists face substantive problems when embracing supervenience, see, J. P. Moreland, "Should a Naturalist Be a Supervenient Physicalist?," Metaphilosophy 29 (1998): 35–57. 394 PhilosoPhia Christi 5.2. The Problem of Causal Drainage The phrase, "causal drainage," refers to how the causal powers of anything dependent upon macrophysical properties is drained away by the causal powers at the microphysical level.47 Consider the following statement from David Papineau: Macroscopic causal patterns do not depend on massive coincidences at the physical level. Rather any macroscopic cause corresponds to a common physical condition satisfied by its realizers, and there is a physical story to be told about why this condition gives rise to the relevant effect.48 Clearly, what does the actual causal work on such a view is the base physical level. Ned Block's causal drainage argument points out a problem for this view. If all physical effects have sufficient physical causes, then whatever causal power we might attribute to anything not at the microphysical level (in our case reasons) is drained away, is reducible to, the microphysical. The causation at any level gives way to causation at the next lower level. The result is that all causation is drained away to the base level. Our proposal is more modest as it applies to the mental only. Our argument is that if naturalism is true, then mental causation is drained away to mechanistic causation. The success of such an argument fills the gap van Inwagen's identifies in Lewis's argument from reason, as it would entail exClusion. To that argument we now turn. 5.3. How Mechanistic Causes Drain Away Personal Causes It is helpful to return to thinking in terms of personal causes and mechanistic causes. Personal causes include, among other things, the reasons and rational explanations of agents. Mechanistic causes do not include reasons, but only allow subpersonal mechanistic explanations. Consider the following picture of personal explanation as representing by the following familiar diagram.49 47. Ned Block, "Do Causal Powers Drain Away?," Philosophy and Phenomenal Research 67 (2003): 133–50. See also Kim, Physicalism, or Something Near Enough, 52–69, for a discussion of this issue in connection with mental-mental causation. 48. Papineau, "Causation Is Macroscopic but Not Irreducible," 140. 49. Both figure 1 and 2 are variations of Jaegwon Kim's often used diagrams. See Kim, Physicalism, or Something Near Enough, 45, 55, and 63. BranDon riCkaBaugh anD toDD Buras 395 R1 R2 P1 P2 mental causation correlation correlation R = Reason/Mental State P = Physical State Figure 1. Personal Explanation Notice that both the physical states and the mental states exercise causal powers. What is unique about personal explanation is that reasons, as used by agents, act as causes both on other reasons/mental states as well as physical states.50 As a result, reasons do act as explanations. Now consider the picture of mechanistic explanation, given naturalism, as represented by the following diagram. R1 R2 P1 P2mechanistic causation supervenience supervenience R = Reason/Mental State P = Physical State Figure 2. Mechanistic Explanation Notice that all the causal work is being done by the physical states. There is no causal relation between mental states or between physical states and mental states. Mental states, in our case reasons, play no causal role. Hence, explanation is reduced to mechanisms and excludes reasons. Because mental states play no causal role, they play no explanatory role. That is, the causal work of the physical states, in virtue of the fact that they fully account for what goes on, drains away the possibility of mental causation. In turn, personal explanation is drained of any explanatory power in virtue of comprehensive mechanistic explanations for any event. Even supposing that mental states exercise causal power, on this picture they would be redundant. 50. One might think, e.g., that at least in some cases the physical and personal causes are each only partial, which avoids concerns regarding overdetermination of explanations. mechanistic causation mental causation 396 PhilosoPhia Christi 5.4. The Argument from Reason and the Problem of Mental Causal Drainage Suppose naturalism is true. It follows that beliefs are physical (although they might have nonphysical properties) as everything is physical. Accordingly, the realizers of mental properties have physical properties and these mental properties are dependent upon the physical properties. Consequently, forming a belief based on reasons is therefore dependent upon the occurrence of a physical event. This is ensured by the conjunction of causal closure and exClusion. The causal closure principle requires that the physical events on which one's beliefs depend have complete mechanistic explanations and therefore complete physical causes. Causal closure is the driving principle behind the widespread acceptance of physicalism.51 This principle plays a prominent role in the mental causation literature under various names, such as completeness of the physical, and causal closure of the physical.52 According to Papineau, the great cost of rejecting causal closure is that there would be no reason to reject substance dualism, a view which holds mental causation and personal explanation as irreducible.53 Moreover, exClusion entails that there can be no other distinct cause of the physical states that fix beliefs. Consequently, the physical states that fix beliefs have no causes distinct from their physical causes. Therefore, the mental properties (reasons) associated with any state prior to one's belief are not causes of that belief. In terms of the causal drainage problem this means that, given naturalism, mechanistic explanations drain away the causal powers of rational explanation. It is not possible to avoid this by saying there is a noncausal reasons explanation because as we specified above, reasons explanations are causal explanations. Although prior mental states may be associated with the physical causes of belief, the physical causes do all the heavy lifting. Only physical causes 51. See David Papineau, Thinking about Consciousness (New York: Oxford University Press, 2002), 13–44, 232–55. 52. On "completeness of the physical," see Tim Crane, "The Mental Causation Debate," Proceedings of the Aristotelian Society, supplementary 69 (1995): 211–36; Tim Crane, Elements of Mind: An Introduction to the Philosophy of Mind (New York: Oxford University Press 2001), 43–8; David Papineau, Philosophical Naturalism (Oxford: Blackwell, 1993); Papineau, Thinking about Consciousness, ch. 1; and Tim O'Connor, and John Ross Churchill, "Is Nonreductive Physicalism Viable within a Causal Powers Metaphysic?," 43–60. On "causal closure of the physical," see Tim Crane, "Mental Causation and Mental Reality," Proceedings of the Aristotelian Society 92 (1992): 185–202; Lynne Rudder Baker, "Metaphysics and Mental Causation," in Mental Causation, ed. John Heil and Alfred Mele (Oxford: Clarendon, 1993), 75–95; Andrew Melnyk, A Physicalist Manifesto: Thoroughly Modern Materialism (New York: Cambridge University Press, 2003), 281–309; and Kim, Physicalism, or Something Near Enough, 49–50, 153–6. 53. Papineau, "Causation Is Macroscopic but Not Irreducible," 149. BranDon riCkaBaugh anD toDD Buras 397 enter into a naturalistic account of the production of beliefs. The acceptance of a belief is explained, like everything else, exclusively in mechanistic terms or mechanistic explanations. Thus, it is not explained in personal terms or rational explanations, and therefore not by reasons. The problem is not that one lacks reasons to believe. The problem is that naturalism leaves no room for one's reasons to play a causal role in the production of belief. If mental states are not causally involved in the production of other mental states, it follows that no one believes anything based on reasons, including the belief that naturalism is true. Of course, naturalism might explain how mechanical devices like calculators and computers act in accordance with reason. However, naturalism cannot explain how persons act from reason, where reason itself is the explanation. It is worth mentioning that appealing to emergence in order to avoid the problem of mental causal drainage does not change the situation for the naturalist. Nonreductive physicalists such as John Searle and Nancey Murphy maintain that mental states, although emergent from brain states, can exhibit top-down causation, causation from emergent mental properties back on the brain from which they emerged.54 This type of nonreductive physicalism has faced a number of criticisms.55 For example, Kim has shown that such a view does not survive the exclusion problem. If a mental state, M, emerges from a physical basal condition P, then, argues Kim, P displaces the causal power of M. Even with M as an emergent mental state, P is sufficient in explaining why any alleged effect of M occurred. This, Kim argues, is true for either a nomological or counterfactual view of causation.56 J. P. Moreland has provided at least two objections to top-down causation.57 First, Moreland argues that there are no accurate examples of emergent top-down causation. Moreland surveys the examples offered by Murphy, Warren Brown, Philip Clayton, and Harold Morowitz explaining how all their examples, save consciousness, are not cases of emergence but of structural supervenience and therefore do not provide analogical evidence for mental states or consciousness to be emergent.58 Secondly, Moreland argues that the conjunction of emergent supervenience and the dominant 54. John Searle, The Rediscovery of the Mind (Cambridge, MA: MIT Press, 1992), 111–12. Nancey Murphy, Bodies and Souls, or Spirited Bodies? (New York: Cambridge University Press, 2006), 78–85. 55. For other arguments against nonreductive physicalism see, Brandon Rickabaugh and C. Stephen Evans, "Neuroscience, Spiritual Formation, and Bodily Souls: A Critique of Christian Physicalism," in Christian Physicalism?, ed. Keith Loftin and Joshua Farris (Lanham, MD: Rowman and Littlefield, 2018); and C. Stephen Evans and Brandon Rickabaugh, "What Does it Mean to Be a Bodily Soul?," Philosophia Christi 17 (2015): 315–30. 56. Jaegwon Kim, "Emergence: Core Ideas and Issues," Synthese 151 (2006): 557–8. 57. J. P. Moreland, "Mental vs. Top-Down Causation: Sic et Non, Why Top-Down Causation Does Not Support Mental Causation," Philosophia Christi 15 (2013): 133–47. 58. See also, Dallas Willard, "Non-Reductive and Non-Eliminative Physicalism?," http:// www.dwillard.org/articles/artview.asp?artID=48. 398 PhilosoPhia Christi physicalist mereological hierarchy, which includes ontological reduction, preempt the causal powers of mental properties. Applied to our purposes, these considerations help show that emergence cannot help the physicalist avoid our argument for exClusion. 5.5. What Really Happened to Phoebe Let's return to Phoebe. Given naturalism she is a purely physical thing, and believes that Lewis fought in the First World War. Suppose this belief fact is explained by a macro property, a rational explanation she reports as, "Lewis states in Surprised by Joy that he fought in the First World War, and no one includes easily detectable falsehoods in an autobiography." However, as van Inwagen states, Phoebe's belief is also completely explained by a complex of mechanistic causes, a complete mechanistic explanation, including facts about the state of the universe long ago, which cause her to believe that Lewis fought in WWI. But, we now have a good reason to think that rations explanation from Phoebe is excluded by the mechanistic explanations from Phoebe. As we have argued, the causal power at work in the rational explanation is drained away by the causal powers at work in the complete mechanistic explanation. That is, the causal power of Phoebe's reasons for believing that Lewis fought in WWI are drained away, are eliminated, because nonrational factors (her brain states in conjunction with the relevant facts about the history of the universe) fully explain why she holds this belief. Because of this, Phoebe's belief is not rational, as it is not based on reasons, but on complete mechanistic causes. Perhaps one might accept overdetermination as a way out of this argument. However, naturalists such as Kim and Papineau are convinced that such a line of response is not available to the naturalist. Papineau, for example, maintains that the rejection of overdetermination is a premise in what he refers to as "the canonical argument for materialism," his causal argument.59 Therefore, rejecting overdetermination is not a live option for naturalism. Others have argued that overdetermination would involve an "intolerable coincidence" that every time someone reasons to a conclusion there are two independent causal lines converging on the same effect, both a complete physical explanation and a sufficient rational or person explanation.60 But such coincidental overdetermination is highly implausible. Consequently, contra van Inwagen, the naturalist can avoid neither the problem of mental causal drainage nor the argument from reason. 59. Papineau, Thinking about Consciousness, ch. 2, esp. 27–8. 60. Melnyk, A Physicalist Manifesto, 291–3. BranDon riCkaBaugh anD toDD Buras 399 6. Conclusion Van Inwagen may be right that Lewis never gave us an argument for exClusion. Our purpose was not to dispute that exegetical issue.61 Instead, we have offered an argument for exClusion: given naturalism, mechanistic explanations drain away the causal powers of rational explanations. Consequently, van Inwagen's objection is undermined. Complete mechanistic explanations exclude personal explanations because the personal or mental causal powers drain away to the mechanistic causal powers. Given naturalism, reasons or the mental have no causal powers. Only the micro mechanistic causal powers at the level of fundamental physics remain. Perhaps van Inwagen would reject our argument, and we are curious how he might reply. Regardless, there need not be a gap in the type of argument from reason Lewis has inspired. 61. For an argument that Lewis does give us an argument for exClusion, see Menuge, Agents under Fire, ch. 6.