Review: Richard Swinburne. 1997. The Evolution of the Soul, Revised Edition. Oxford: Clarendon Press. xiv+360 pp.
Most contemporary philosophers are physicalists. They believe that, in a relevant sense, everything (including tables, clouds, cars, the universe and even our sensations) is ultimately physical. Recently, mainly because of David J. Chalmers’ influential work on phenomenal consciousness (Chalmers 1996), some philosophers have started to take property dualism more seriously (the thesis that the mental and the physical are two fundamentally distinct kinds of property). They think that while there are a number of strong arguments for physicalism, the physical sciences might not be able to account for everything in the world. However, very few contemporary philosophers take substance dualism seriously (the thesis that the mental–what Swinburne calls the soul–and the physical are two distinct kinds of substance that interact with each other).
In The Evolution of the Soul Richard Swinburne makes a courageous attempt to defend substance dualism. The book is based on two series of Gifford Lectures that he delivered in 1983 and 1984. The first edition of the book was published in 1986 and this revised edition in 1997. In the main, he made only minor revisions for the second edition, but added a number of new appendices. I welcome Swinburne’s contribution to the philosophy of mind because substance dualism, whether it is ultimately tenable or not, is often dismissed too quickly. In the following, I summarize the content of the book and then evaluate Swinburne’s arguments for substance dualism.
2. Summary of the Book
After Chapter 1, the Introduction, the book is divided into three parts. In Part I, which consists of Chapters 2 to 7 inclusive, Swinburne argues that mental events and physical events are ontologically distinct. In Chapters 2 and 3 he argues that behaviorism and the identity theory are false because they fail to provide a satisfactory explanation of sensations. In Chapters 4 to 7 he considers such notions relevant to mental activities as thoughts, purposes, desires and beliefs. He rejects epiphenomenalism by appealing to the causal efficacy of conscious episodes. His argument for such causal efficacy is based on both philosophical and biological grounds.
In Part II, which consists of Chapters 8 to 10 inclusive, he defends substance dualism. In Chapter 8 he argues that truths about persons are other than truths about their physical bodies. In Chapters 9 and 10 he provides responses to various questions that substance dualism faces: What is the nature of personal identity? When do souls begin to exist and how do they evolve? Could artificial creatures ever have souls?
In Part III, which consists of Chapters 11 to 15 inclusive, he considers the structure and capacities of the human soul in contrast with animal souls. From Chapters 11 to 13 he argues that the human soul is different from animal souls because it has powers of complex and logically ordered thought, an awareness of moral goodness and obligation, and freedom of will. In Chapter 14 he argues that although the structure and character of the human soul rely partly on the brain, it is essentially independent. In Chapter 15 he discusses various arguments for the claim that the human soul continues to function without the brain functioning. He finds arguments from parapsychology and natural survival untenable. He concludes that the only possible argument for the claim has to go beyond nature.
3. Evaluating Swinburne’s Arguments
Swinburne defends substance dualism in a number of different ways, but in the following I will focus on and critically analyze two arguments that he provides in defense of his doctrine.
(i) In New Appendix C (pp. 322-332) Swinburne provides the following argument that purports to show that my existence as a conscious person now entails the existence of my soul:
(1) I am a conscious person and I exist in 2004.
(2) It is possible that I survive into 2005, given that I am conscious in 2004, even if my body is totally destroyed and whatever else might be the case in 2004, compatible with these last two suppositions.
(3) It is not possible that I who am conscious in 2004 survive into 2005 if my body is totally destroyed, unless there is a non-bodily part of me in 2004, namely, a soul.
(4) The fact that I am a conscious person and I exist in 2004 entails that I have a soul in 2004 (322).
In order to schematize this argument Swinburne introduces the following symbolization:
p = ‘I am a conscious person and I exist in 2004’.
q = ‘My body is destroyed in the last instant of 2004’.
r = ‘I have a soul in 2004’.
s = ‘I exist in 2005’.
x ranges over all consistent propositions compatible with (p&q) and describing states of affairs in 2004.
‘(x)’ is to be read … as ‘for all x’ (322).
[Ed: Nagasawa has updated Swinburne’s example by using 2004 and 2005 in place of Swinburne’s original 1984 and 1985, respectively.]
Using the usual logical symbols, ‘&’ as ‘and,’ ‘~’ as ‘not,’ and ‘<>’ as ‘it is logically possible that,’ Swinburne schematizes the argument as follows:
(2*) (x) <> (p & q & x & s)
(3*) ~ <> (p & q & ~r & s)
(4*) p entails r (322-323).
(2*) and (3*) jointly entail that ~r is not within the range of x. But since ~r describes a state of affairs in 2004, it follows that it is not compatible with (p&q). Hence, (p&q) entails r. However, the addition to p of q, which describes what happens to my body at the end of 2004, can hardly affect whether or not p entails r. Therefore, p by itself entails r (322-323).
[Ed: The format in which Swinburne presents his symbolized argument has been slightly changed here by the author for easier presentation.]
Although critics have already provided a variety of objections to Swinburne’s argument, I introduce in the following yet another objection.
I submit that Swinburne’s argument is either invalid or unmotivated, depending on how it is interpreted. In order to defend (2), Swinburne provides two logically possible cases: (a) a case in which a person becomes disembodied and (b) a case in which the scope of one’s bodily control gradually shifts from one’s own body to someone else’s body (pp. 151-152). (a) cannot be used legitimately, at least in this context, because it implicitly assumes the existence of the soul. Suppose then that (b) is possible. Suppose, using Swinburne’s example, that one morning a person wakes up to find himself unable to control the right side of his body, including his right arm and leg. When he tries to move the right-side parts of his body, he finds that the corresponding left-side parts of his wife’s body move. This process continues until the person’s control is completely shifted to his wife’s body and his wife completely loses her control of it (p. 151). Assuming that this scenario is logically possible and that the same thing could happen to me, (2) is obviously true. It is possible that I survive into 2005, given that I am conscious in 2004, even if my body is totally destroyed and whatever else might be the case in 2004, compatible with these last two suppositions. For the control of my body could shift completely to someone else’s body before the destruction of my body.
(3) says that it is not possible that I, who am conscious in 2004, survive into 2005 if my body is totally destroyed unless there is a nonbodily part of me in 2004; namely, a soul. The important question here is exactly how we interpret the phrase ‘my body’ in (3). There are two possible interpretations. The first is that ‘my body’ refers to my current body, that is, whatever body that I have now. According to this interpretation, (3) means the following:
(3′) It is not possible that I, who am conscious in 2004, survive into 2005 if my current body is totally destroyed unless there is a nonbodily part of me in 2004; namely, a soul.
Suppose that my current body is totally destroyed in 2004. If I am nothing but my current body, the destruction of my body is the end of my existence. Hence, it is perfectly plausible to say in this context that unless there is a nonbodily part of me in 2004, I cannot survive into 2005. Thus (3′) is true.
However, Swinburne cannot adopt this interpretation of the phase ‘my body’ in his argument. For, unlike (3′), (2) assumes that ‘my body’ refers to my original body, rather than my current body. When (2) says that I can survive the destruction of my body, it means that I can survive the destruction of my original body, not my current body. Hence, if we adopt the first interpretation of the phrase, (2) and (3) could refer to different bodies and thus Swinburne’s argument turns out to be invalid.
On the second interpretation, ‘my body’ refers to my original body. That is, according to this interpretation, (3) means the following:
(3”) It is not possible that I, who am conscious in 2004, survive into 2005 if my original body is totally destroyed unless there is a nonbodily part of me in 2004; namely, a soul.
On this interpretation, (2) and (3) refer to the same body–viz., my original body–and Swinburne’s argument remains valid. However, this interpretation renders his argument unmotivated. Given the plausibility of the bodily control shift scenario, it is possible that I–who am conscious in 2004–survive into 2005 if my original body is totally destroyed. Now the truth-value of (3”) depends on whether or not the existence of the soul is the only possible explanation for the bodily control shift. However, it has not been shown that the soul is the only possible explanation. (Indeed, it seems impossible for Swinburne to show this without begging the question against opponents of this argument.) Hence, on the second interpretation of the phrase ‘my body,’ Swinburne’s argument is unmotivated.
Therefore, depending on how one interprets the phrase, Swinburne’s argument is either invalid or unmotivated.
(ii) Swinburne’s dualism is a version of Cartesian dualism because it involves the thesis that mental events and physical events causally interact with each other. Most contemporary philosophers reject Cartesian dualism because of this very thesis. They claim that if, as Swinburne and Cartesian dualists say, there is a significant ontological gap between mental events and physical events, then it is impossible for them causally to interact with each other. Conversely, if mental events and physical events do causally interact with each other, they claim, there cannot be a significant ontological gap in the first place. While Swinburne admits that he cannot explain how interaction works, he does not find this to be a serious problem for his dualism. He writes:
I had indeed not discussed [this objection to substance dualism], for the simple reason that it seems no good argument against the existence of a causal connection which can be repeated endlessly at will, that we cannot explain how it works. That bodily events cause brain events and that these cause pains, images, and beliefs (where their subjects have privileged access to the latter and not the former), is one of the most obvious phenomena of human experience. If we cannot explain how that occurs, we should not try to pretend that it does not occur. We should just acknowledge that human beings are not omniscient, and cannot understand everything (xi).
Swinburne’s claim seems to beg the question against antidualism. The dialectical situation here is the following: Swinburne and other Cartesians claim that dualism is true because it is obvious that the mental and the physical are ontologically distinct entities that interact with each other. In response to this claim, antidualists (such as physicalists) reject dualism on the ground that if the mental and the physical are ontologically distinct, the interaction between them is impossible. Swinburne cannot reject this antidualist objection by simply repeating that it is obvious that mental events and physical events are ontological distinct entities that interact with each other.
If Swinburne is going to insist that the interaction is real but inexplicable, he needs to at least explain why it is inexplicable. In Chapter 10 Swinburne tries to explain this by appealing to what he takes to be Colin McGinn’s argument for the insolubility of the mind-body problem (McGinn 1989). Swinburne says that we cannot fully explain the interaction between the mental and the physical because physics or chemistry cannot “be enlarged so as to become a super-science dealing with both physical and mental properties.” Scientists can “compile a very, very long list of the correlations between brain-events and sensations,” but mere correlation does not provide a full explanation (pp. 188-190). He says, moreover, that the inexplicable interaction between the mental and the physical provides a reason to believe in the existence of God:
So if we cannot give a normal scientific explanation of how brain-events cause mental events and conversely, we should seek a personal explanation. Invoking a personal explanation in this case involves invoking God, a power behind nature, who intentionally keeps the laws of nature operative … and also brings it about that there is linked to the brain of an animal or man a soul which interacts with it in a regular and predictable way…. [T]he ability of God’s actions to explain the otherwise mysterious mind-body connection is just one more reason for postulating his existence (198).
I have three responses to Swinburne’s argument here.
First, contrary to what Swinburne says, his argument is different from McGinn’s. McGinn maintains that we cannot solve the mind-body problem because we are cognitively closed with respect to the solution to the problem. That is, according to McGinn, while there is a solution to the problem, human beings are denied access to it because of our unique cognitive limitations. Swinburne’s argument, however, does not refer to such cognitive limitations. Moreover, McGinn explicitly denies that his argument entails anything supernatural, such as the existence of God; for he thinks that there are possible creatures with different cognitive capacities from ours that are able to access the solution.
Second, while Swinburne’s argument might motivate dualism in general, it does not motivate substance dualism in particular. For, if Swinburne’s argument is successful, it shows only that mental events are not fully explicable using physical terms. Whether or not the interaction between the mental and the physical is explicable is a different issue. Evidently, many property dualists, whose doctrine is inconsistent with Swinburne’s substance dualism, endorse arguments similar to Swinburne’s.
Third, Swinburne’s argument does not provide a reason to believe in the existence of God. For even if Swinburne is right in saying that the physical sciences cannot explain the interaction between the mental and the physical, this putative fact does not immediately invoke the notion of a divine personal creator of the universe. It is perfectly possible that there is a natural–but not scientific–explanation for the interaction, or that there is a supernatural–but neither personal nor divine–explanation for it. On the other hand, if we take Swinburne’s lead and attribute the inexplicability to God, it is hard to see God’s purpose for precluding us from understanding the interaction.
As we have seen, Swinburne’s arguments for substance dualism are not very compelling. However, I still find The Evolution of the Soul worth reading as it contains a number of interesting and illuminative ideas that contemporary philosophers of mind tend to overlook. It would be a significant mistake to dismiss the book simply because one is not sympathetic to Swinburne’s theism.
 See William P. Alston and Thomas W. Smythe (1994), Nicholas Everitt (2000), William Hasker (1998), Kent Reames (1999), Eleonore Stump and Norman Kretzmann (1996).
Alston, William P. and Thomas W. Smythe. “Swinburne’s Argument for Dualism.” Faith and Philosophy 11 (1994): 127-133.
Chalmers, David J. The Conscious Mind. Oxford: Oxford University Press, 1996.
Everitt, Nicholas. “Substance Dualism and Disembodied Existence.” Faith and Philosophy 17 (2000): 331-347.
Hasker, William. “Swinburne’s Modal Argument for Dualism: Epistemically Circular.” Faith and Philosophy 15 (1998): 366-372.
McGinn, Colin. “Can We Solve the Mind-Body Problem?” Mind 98 (1989): 349-366.
Reames, Kent. “A Response to Swinburne’s Latest Defense of the Argument from Dualism.” Faith and Philosophy 16 (1999): 90-97.
Stump, Eleonore and Norman Kretzmann. “An Objection to Swinburne’s Argument for Dualism.” Faith and Philosophy 13 (1996): 405-414.
Copyright ©2005 Yujin Nagasawa and Internet Infidels, Inc.