by John M. DePoe
Western Michigan University
from: http://www.johndepoe.com/dualism.pdf ; quoted at the philosophical archive for the constructive study of ontological dualism: www.newdualism.org.
Substance dualism is not among the most popular theories of mind in contemporary philosophy. Although, a number of significant contemporary philosophers maintain that property dualism1 or substance dualism2 is true. In philosophy, however, truth is not decided by the popularity of a theory but by the arguments that support it. In this essay, I will attempt to provide arguments that support substance dualism. I will also consider counterarguments to dualism at the end of this essay.
What do I mean by "dualism"? For my purposes, dualism is the theory that there are two separate classes of properties: material and immaterial. If these distinct properties are understood to have substantial, enduring existence, then the theory can be called substance dualism. Insofar as substance dualism relates to humans, it means that humans consist of two connected substances: the material body and the immaterial mind. The popular alternative to dualism is monism, the view that only material substances and properties exist.3 My case for dualism follows, to some degree, on the grounds that monism fails to account for all of the features of the mind.
1 For example, Thomas Nagel, "What is it Like to be a Bat?" Philosophical Review 83, no. 4 (1974): 435-50; Saul Kripke, "Naming and Necessity"in Donald Davidson and Gilbert Harmon, eds ., Semantics of Natural Language (Dordrecht: Reidel, 1974), 253-355 and 763-69; Frank Jackson, "Epiphenomenal Qualia," Philosophical Quarterly 32 (1982): 127-36; David Chalmers, The Conscious Mind (Oxford: Oxford University Press, 1996.
2 For example, W. D. Hart, The Engines of the Soul (Cambridge: Cambridge University Press, 1988); John Foster, The Immaterial Self: A Defense of the Cartesian Dualist Conception of the Mind (London: Routledge, 1991); David Braine, The Human Person: Animal and Spirit (Notre Dame, IN: University of Notre Dame Press, 1992); Richard Warner, In Defense of Dualism, in Richard Warner and Tadeusz Szubka, eds., The Mind-Body Problem (Cambridge, MA: Blackwell, 1994); Charles Taliaferro, Consciousness and the Mind of God (Cambridge: Cambridge University Press, 1994); Eleanor Stump, "Non-Cartesian Substance Dualism and Materialism without Reductionism, in Faith and Philosophy 12 (October 1995): 505-31; Richard Swinburne, Is There a God? (Oxford: Oxford University Press, 1996), ch. 5; idem., The Evolution of the Soul, 2d ed. (Oxford: Oxford University Press, 1997); William Hasker, The Emergent Self (Ithaca, NY: Cornell University Press, 1999).
3 In the contemporary literature monism has been cashed out in a number of ways including type identity theories, token identity theories, functionalist theories (which are not essentially materialistic), and eliminative materialism.
The first step in my case for dualism is to establish property dualism.4 Thomas Nagel in his famous article, "What is it Like to be a Bat?" shows that there is an irreducible, subjective, first-person feel as to what-it-is-like-to-be that cannot be captured in an objective, third-person description. Saul Kripke's argues that physical and mental properties cannot be identical because this would entail that the identification is necessary, but we know that this identification is not necessary. Property dualism also follows from Frank Jackson's thought experiment about Mary, the super scientist. In the thought experiment, Mary is a super scientist who knows every scientific fact in comprehensive detail but has lived her whole life in an environment that consists of black and white colors. One day, Mary ventures out of her black and white environment and sees something red, resulting in her learning something new (i.e., what it's like to see red). Therefore, there is more to the world than third-person scientific facts—there are first-person, subjective, experiential facts as well. Finally, David Chalmers has argued from the conceivability of possible zombie worlds that it is possible for a physically identical world like ours to exist, except there would be no conscious people, only zombies. Since conscious people exist in the actual world that is physically identical with the conceivable zombie world, there must be more properties than merely physical ones in the actual world.
I believe that the arguments given above for property dualism all roughly illustrate that material and mental properties fail to be identical according to Leibniz's law of the identity of indiscernibles. Leibniz's law states that for all x and y, ifx and y have all and only the same properties, then they are identical to each other. Or symbolically:
(x)(y)[(P)(Px↔Py) → (x=y)]
4 See footnote 1 for references that correspond to works cited in this paragraph.
The reason why these arguments point to property dualism is that the properties of mental phenomena cannot be identical with material properties. Immaterial properties would include mental phenomena such as first-person experiences. These experiences are not spatially located, do not have physical properties (electrical charge, mass, volume, etc.), they are self-presenting, and they are accessible only from the first-person point of view. On the other hand, the physical properties that characterize the brain are spatially located, possess physical properties, are not self-presenting, and are not characterized by a first-person point of view. Since no physical property could be identical with the properties of what-it-is-like-to-be conscious, it is necessary to postulate immaterial properties to account for these mental phenomena.5
John Searle has said that these arguments (excluding Chalmers's, which had not yet been written) are "ludicrously simple and quite decisive" in showing that mental experiences cannot be reduced to physical properties.6 Unless one is willing to deny first-person experiences exist (including one's own),7 it seems that the arguments for property dualism present a better explanation for the data of the mind that needs to be explained.
5 As Zeno Vendler writes ("The Ineffable Soul" in The Mind-Body Problem, 318): "[T]he elements of consciousness, the buzzing-blooming confusion of our Humean selves are in principle beyond what science can explain. And here is not just a matter of two incommensurate conceptual networks grappling with the same reality. In this case we have the emergence of an altogether new domain: content of experience, essentially subjective, thus inaccessible to any public, interpersonal, conceptual system."
6 John Searle, The Rediscovery of the Mind (Cambridge, MA: MIT Press, 1992), 118. Searle, however, thinks that nothing interesting follows from the success of these antireductionist arguments.
7 My convictions side with Swinburne's, Does God Exist?, 71: "Evidently—more evidently than anything else—there really are mental events, as we know from our own experience." Compare Searle, Rediscovery, 20: "The ultimate absurdity is to try to treat consciousness itself independently of consciousness, that is, to treat it solely from a third-person point of view, and that leads to the view that consciousness as such, as "inner,' "private' phenomenal events, does not really exist."
Property dualism is one thing, but making the case for substance dualism is another. The first reason why I think substance dualism is true is that all conscious individuals have an immediate and direct awareness that they are not identical with a material body or a bundle of mental events, but that they are "a seat of consciousness" that possesses a body and experiences mental events. This "seat of consciousness" is not a material thing, nor is it divided up as a series of disconnected mental events. In other words, it is necessary to postulate that there is a subsisting immaterial "seat of consciousness" to account for this immediately and directly known awareness about oneself. Rene Descartes understood this when he wrote, "For in reality, when I consider the mind—that is, when I consider myself in so far as I am only a thinking being—I cannot distinguish any parts, but I recognize and conceive very clearly that I am a thing which is absolutely unitary and entire."8 Likewise, Immanuel Kant argued for a unitary and subsisting immaterial self:
Every composite substance is an aggregate of several substances, and the action of a composite, or whatever inheres in it as thus composite, is an aggregate of several actions or accidents, distributed among the plurality of substances. Now an effect which arises from the concurrence of many acting substances is indeed possible, namely, when this effect is external only (as, for instance, the motion of a body is the combined motion of all its parts). But with thoughts, as internal accidents belonging to a thinking being, it is different. For suppose it be the composite that thinks: then every part of it would be a part of the thought, and only all of them taken together would be the whole thoughts. But this cannot consistently be maintained. For representations (for instance, the single words of a verse), distributed among different beings, never make up a whole thought (a verse), and it is therefore impossible that a thought should inhere in what is essentially composite. It is therefore possible only a single substance, which, not being an aggregate of many, is absolutely simple.9
8 Rene Descartes, Meditations on First Philosophy, book 6.
9 Immanuel Kant, Critique of Pure Reason, A 352.
This is related to the irreducibility of the first-person point of view. Certain indexicals, like "I", "here", and "how" have meaning that is lost when "translated" into sentences that eliminate these essential indexicals.10 In the case of "I", to what does this indexical refer? Presumably, when someone uses the indexical "I", it is not referring to any material properties or a bundle of mental properties. The apparent referent is to one's self-awareness of oneself as an enduring and unified self.
Another argument supporting substance dualism is that one maintains personal identity through change. Even though one is continuously going through physical changes and experiencing different mental states, a person continues to be the same person. If persons were identical with their physical parts or mental states, they would cease to be the same persons as these changes occurred. Therefore, it is necessary to postulate an immaterial, substantial self that endures through change.
Suppose that someone believes that people do not maintain identity through change and concludes that the previous argument for substance dualism fails. This denial of personal identity through change, I contend, presents untenable difficulties. First, there is one's own awareness of being the same person through change. Moreover, if one is not literally the same person through these changes, how can a person maintain long-term goals and desires? As Christine Korsgaard has noted, "You are one continuing person because you have one life to lead."11 For example, suppose Timmy wants to earn a Ph.D. in philosophy. If Timmy does not endure through change, he is choosing a future that he will not enjoy. Rather, a later time-slice of Timmy will go to graduate school in philosophy, not the Timmy who wanted the Ph.D. So, without an enduring self the Timmy who worked hard and desired to go to graduate school will not be identical to the Timmy who attends graduate school. Furthermore, the time-slice of Timmy that goes to graduate school may not want to be in graduate school. This theory of the self is utterly foreign to one's own experience, and if one came to believe it, it would utterly annihilate any motivation or responsibility for long-term decisions. Why work hard for payoffs that someone else will enjoy?
10 See especially John Perry's, "The Problem of the Essential Indexical," Nous 13 (1971): 3-21.
11 Christine Korsgaard, "Personal Identity and the Unity of Agency: A Kantian Response to Parfit," Philosophy and Public Affairs 18, no. 2 (1989): 113.
The above point can be extended. The practical results of denying substance dualism are untenable from a practical point of view. Strictly speaking, denying an enduring self would entail that it is wrong to punish convicted criminals who have reached a point where they are no longer identical with the physical and mental bundles that were identical with the people who committed their respective crimes. Likewise, it would be wrong to reward Nobel laureates for their achievements since the people receiving the awards would not literally be the same persons who accomplished the great intellectual feat. The practical results that follow from rejecting a unified self would require a Copernican revolution in practical reasoning. While this is not, strictly speaking, an argument for dualism, it demonstrates the high costs that result from denying an enduring self.
A final reason for supporting dualism is that material monism shows little prospects for accounting for the rich mental experiences people have. For example, consider Richard Swinburne's criticism of monism:
If monism were correct, then there would be nothing more to the history of the world than the succession of those events which involve material substances, their coming into existence or ceasing to exist and having properties and relations (physical or mental). But, I am now going to point out, if you knew all that, you would still not know one of the most important things of all—whether you or any other human continued over time to live a conscious life.
This critique focuses on the failure of monism to account for the immaterial properties of consciousness, but there are other implications that follow. If humans are merely caught up in a series of physical causes that are closed in a mechanical system determined by physical laws, this leaves no room for human agency to bring about free actions and rational beliefs.13 Dualism, on the other hand, has no problem accounting for the properties of the mind, and the role of personal agency to bring about free actions, intentionality, and rationality. So, part of my case for dualism rests on the claim that physical monism is ontologically impoverished to account for the full range of mental phenomena presented in one's own experience.
The arguments I have presented follow from observations and arguments about the mind. It may seem that my arguments are too simple and that I incorrectly portray opponents to dualism as denying transparent facts. Next, I hope to bring some balance to my presentation by considering some of the leading arguments against substance dualism. While I maintain that substance dualism is a convincing theory, it should become clear that many other views can be credible and convincing given certain assumptions and depending on how severe one counts the arguments against dualism.
12 Swinburne, Is There a God?, 73-74.
13 Substantiating this claim in further detail is beyond the scope of this essay. I am currently researching the need for personal agency to account for rationality, which I plan on giving as my final paper in this class. Those who agree with this controversial claim include Norman Malcolm, "The Conceivability of Mechanism," Philosophical Review 77 (1968): 45-72; Warner Wick, "Truth's Debt to Freedom," Mind 73 (1964): 527-37; James N. Jordan, "Determinism's Dilemma," Review of Metaphysics 24 (1969-1970): 48-66; Karl Popper, "Of Clouds and Clocks," in Objective Knowledge: An Evolutionary Approach (Oxford: Clarendon, 1972); William Hasker, "The Transcendental Refutation of Determinism," Southern Journal of Philosophy 11 (1973): 175-83; Lynne Rudder Baker, Saving Belief: A Critique of Physicalism (Princeton, NJ: Princeton University Press, 1987); Hasker, Emergent Self, 58-80; Swinburne, Is There a God?, 91-94; Swinburne, Evolution of the Soul, 231-61; Dallas Willard, "Knowledge and Naturalism," in J. P. Moreland and William Lane Craig, eds., Naturalism: A Critical Analysis (New York: Routledge, 2000), 24-48; Robert Koons, "The Incompatibility of Naturalism and Scientific Realism," in Naturalism: A Critical Analysis, 49-64; Charles Taliaferro, "Naturalism and the Mind," in Naturalism: A Critical Analysis, 133-55; Stewart Goetz, "Naturalism and Libertarian Agency," in Naturalism: A Critical Analysis, 156-86; Victor Reppert, "Causal Closure, Mechanism and Rational Inference," Philosophia Christi 3 (2001): 473-84; Mark Thomas Walker, "The Freedom of Judgment," International Journal of Philosophical Studies 11, no. 1 (2003): 63-92.
Perhaps the chief objection to dualism questions how two utterly different properties can interact with one another. In other words, it seems implausible to imagine how a mind lacking any material properties could interact with a body lacking any immaterial properties. This is a difficult question for dualists to face, and I would concede that no plausible explanation for how causal interaction occurs between mind and body has been given. Indeed, the question of causal interaction is the "hard problem" for dualism.
Nonetheless, I do not believe the problem of causal interaction is devastating for dualism. Since this objection does not show that it is logically impossible for such interaction to take place, it only highlights an epistemic problem-niamely that we do not know how such interaction takes place. The problem of interaction, however, raises no ontological impossibility for dualism. Currently causal interaction is epistemically inexplicable for dualists, but this should not be surprising since many aspects of the mind and causation are utterly inexplicable at this time.
Another leading objection to dualism is that dualism is not consistent with science. There are at least two ways this objection has been raised. The first way this objection is stated claims that dualism cannot square with the biological story given by evolution. This version of the objection from science is categorically false, which is evident by the way certain dualists have drawn on evolutionary biology to support their position.14
14 In particular, see Hasker, Emergent Self and Swinburne, Evolution of the Soul.
Another approach that the objection from science can take is more applicable. This approach takes the conviction that using a materialistic worldview must be compatible with an account of the mind. David Armstrong's comments candidly express this point of view:
What does modern science have to say about the nature of man? There are, of course, all sorts of disagreements and divergences in views of individual scientists. But I think it is true to say that one view is steadily gaining ground, so that it bids fair to become established scientific doctrine. This is the view that we can give a complete account of man in purely physico-chemical terms. [...]
For me, then, and for many philosophers who think like me, the moral is clear. We must try to work out an account of the nature of mind which is compatible with the view that man is nothing but a physico-chemical mechanism.15
This commitment to materialism, while motivated by a noble trust in science, should only be maintained insofar as it is capable of accounting for the phenomena it is invoked to explain. If my arguments for property and substance dualism are cogent, however, then this commitment to materialism must be abandoned. No scientific discovery seems possible to account for the mental phenomena I presented above. The stalwart materialist is left at odds to account for mental phenomena. Take, for example, J. J. C. Smart's confession: "So sensations, states of consciousness, do seem to be the one sort of thing left outside the physicalist picture, and for various reasons I just cannot believe that this can be so."16 Smart's argument continues, like the strategy of many materialists, by eliminating the mental phenomena that threatens to unseat materialism. At this point, materialists, like Smart, are allowing their conclusion to interpret the premises of their argument, which seems like a wrongheaded method to understand the mind.
15 David M. Armstrong, "The Nature of Mind," in The Nature of Mind and Other Essays (Ithaca, NY: Cornell University Press, 1981); reprinted in Brian Cooney, ed., The Place of Mind (Belmont, CA: Wadsworth, 2000), 136-37 (page references correspond to the reprint).
16 J. J. C. Smart, "Sensations and Brain Processes," Philosophical Review 68 (1959): 141-56; reprinted in Place of Mind, 86 (page references correspond to the reprint).
Dualists can reject materialism on the grounds that they have argued and reasonably demonstrated that the mind cannot be entirely material. Materialists, on the other hand, only seem able to maintain their conviction by denying what seems obvious or placing hope that in some future date science will explain what seems inexplicable today. As Swinburne notes, though, one ought to recognize the limits of science:
[SJcience needs to explain both why certain things happen in the brain and why people have certain experiences. If it was able only to explain one of these things, there would be something occurring in the world which it had failed to explain. [...] Science must start from the data of experience, and these include sensations. And if it finds some of these too difficult to explain in terms of current theories, it should openly acknowledge this fact; not pretend that what it cannot explain does not exist.17
Another way to reject dualism, offered by John Searle, is to redefine materialism. Searle suggests that contemporary philosophy of mind takes its cue from a set of issues and terms that presents a false dichotomy.18 Consciousness is not a problem for materialists according to Searle. The problem is that materialists do not see that consciousness is a natural capacity of material, scientific processes. "Consciousness, in short," Searle writes, "is a biological feature of human and certain animal brains. It is caused by neurobiological processes and is as much part of the natural biological order as any other biological features such as photosynthesis, digestion, or mitosis."19 Once one accepts that the rich experiences of consciousness are as natural as photosynthesis, the threat of dualism seems to vanish.20
17 Swinburne, Evolution of the Soul, 60.
18 Searle, Rediscovery, 13-14: "In contemporary philosophy of mind, the historical tradition is blinding us to the obvious facts of our experiences, giving us a methodology that make obviously false hypotheses seem acceptable."
19 Ibid., 90.
20 Ibid., 91: "And once you accept our world view the only obstacle to granting consciousness its status as a biological feature of organisms is the outmoded dualistic/materialistic assumption that the "mental' character of consciousness makes it impossible for it to be a "physical' property."
Searle's attempt to uphold both consciousness an d materialism is one of the most innovative moves in philosophy of mind. If Searle is right, he is correcting an entire field of study that has gone astray at its most fundamental level. At this juncture, however, the disciplinary insurrection Searle is calling for does not seem more cogent than the current semantics used in philosophy of mind. I admire Searle's unashamed recognition of the irreducibility of consciousness with which I heartily concur. What remains questionable is his move to redefine materialism so as to include the properties of consciousness. The exact same properties of consciousness seem applicable to ghosts, ghouls, and God—all of which are essentially immaterial. If Searle's restructuring of the categories of the philosophy of mind is broad enough so that materialism includes all of these traditionally immaterial entities, it seems trivial to call it materialism.
This concludes my brief defense of dualism. While I acknowledge that many find the "hard problem" of causal interaction discredits dualism, I find it more difficult to discard dualism. Likewise, many reject dualism on the grounds that it is inconsistent with scientific materialism. Others may stretch the definition of materialism to include the properties traditionally subsumed under dualism. At the end of the day, however, I find dualism gives the most satisfying account of the phenomena of the mind.