Chisholm's Simple Souls vs. Clark's Extended Selves1 Selmer Bringsjord [email protected] version of 020411-1045NY As the bibliography for his volume (XXV) of The Library of Living Philosophers attests, and as his many students confirm, the late Roderick Chisholm grappled indefatigably for decades with problems related to personhood. Toward the end of his storied and seminal career, Chisholm directed his attention toward the view of the self encapsulated under the phrase \simple souls." Proponents of simple souls include Augustine, Descartes, and Bolzano, but the clearest expression of the doctrine, and the most formidable defense of it, has been given by Chisholm (1989, 1991). Following the other just-mentioned famous friends of simple souls, Chisholm uses the term `soul' or `self' to simply mean the same thing as `person'; he is thus talking about us: beings who persist through time and exemplify diverse mental properties | judging, wondering, desiring, believing (in the occurrent sense), wishing, hoping, enjoying | which themselves have certain key (to- be-discussed-below) properties. According to the doctrine of the simplicity of the soul, we are unextended and incorporeal substances.2 Here is Chisholm just before defending the simplicity of the soul: I will defend the thesis according to which there is something that is metaphysically unique about persons: we have a nature wholly unlike anything that is known to be true of things that are known to be compound physical things. I will attempt to show how this thesis coheres with the traditional doctrine of \the simplicity of the soul." And I will argue that the doctrine of the simplicity of the soul is, in William James' terms, very much a live option. (Chisholm 1991: 167) After briefly discussing the defense to which Chisholm here alludes, I present an attack on it that Chisholm never anticipated, one built from the view, recently defended by Andy Clark (and David Chalmers), that selves extend beyond the human bodies in which they are usually taken to be \enclosed." I then show that Chisholm and other friends of simple souls have nothing to fear from this attack. 1 Chisholm's Argument In the space we have here, Chisholm's argument for the simplicity of the soul can't be treated in the detail it deserves, but a level of detail sufficient for the purposes at hand can probably be reached. Chisholm's starts by encouraging us to examine our mental properties | fearing ghosts, in- tending to work another two hours, believing that Frege's Axiom V has been successfully replaced by the axiom-schema of separation, etc. Such examination, according to Chisholm, reveals that our mental properties have five structural properties, viz., 1As is the case with nearly all philosophy I write, I'm indebted to Jim Fahey (who himself studied at Brown during some of Chisholm's rather extended tenure there) for insightful comments and suggestions on many of the topics treated herein. A full version of this paper, which perhaps at some point I'll get around to writing, would include systematic consideration of emergentism as set out and defended by Fahey and Zenzen (the latter a thinker whose thoughts on some of the matters here analyzed have also been quite helpful), and more recent statements of the \extended mind" view by Clark. 2The simplicity of the soul ought not to be confused with the doctrine of divine simplicity, a radically different notion. Note also that the use of `soul' in Chisholm's simplicity account contrasts with it Aristotelian usage, according to which we could only be said to have souls, not be them. These issues, and others, are discussed in a paper by the late Philip Quinn (1997) on simple souls, to which Chisholm (1997) replies. [RC and PQ were together at Brown for many years before PQ moved to Notre Dame.] 1 (S1) Mental properties are open, in the sense that a property is open iff it is possibly such that, for any number n, there are n substances that have it, and n substances that don't. (S2) Mental properties are repeatable, where a property is repeatable iff it is possibly such that there is something that doesn't have it, but did have it and will have it. (S3) Mental properties are not compositive, where a property is compositive iff it is necessarily such that whatever is composed of things that have it is itself a thing that has it. (S4) Mental properties aren't divisive, where a property is divisive iff it is necessarily such that any com- pound thing that has it has a proper part that has it. (S5) Mental properties are internal properties of substances, where a property is an internal property of substances iff it is necessarily such that whatever has it is a substance, and either it is necessary to whatever has it or it is necessarily such that whatever has it has every open and repeatable property it implies. Ignoring certain technical details that needn't detain us,3 Chisholm then defines a qualitative property as one that is open and repeatable, neither compositive nor divisive, and internal. Now here is his argument (Chisholm 1991: 177) for simple souls: Arg1 (1) We have qualitative properties. (2) Every qualitative property that we are acquainted with is known to be possibly such that it is exemplified by simple substances. (3) No qualitative property is known to be such that it may be exemplified by compound substances. .·. (4) Some of our properties are known to be such that simple substances can have them and are not known to be such that compound substances can have them. .·. (5) We have a nature which is wholly unlike the nature that anything known to be a compound physical thing is known to have. Those who, like Chisholm himself, find the argument to be a powerful defense of simple souls, must apply disjunctive syllogism in a manner that falls beyond Arg1. As Chisholm writes: [T]he conclusion of this argument leaves us with two possibilities: either (a) the soul is an unextended substance or (b) souls have a type of property that extended physical substances are not known to have. The latter option is defended by those who have argued that the fact of thinking indicates the presence of a peculiar type of \emergent property" in nature. (1991: 177) The fact of the matter is that the soundness of Arg1 is perfectly consistent with some such view as that we are extended souls (brains, perhaps; or maybe proper physical parts of brains) that have properties not known to be possessed by extended things. So for Chisholm, and for other contemporary friends of simple souls (e.g., Philip Quinn 1997), the power of Arg1 hinges on whether or not some form of emergentism (according to which our mental properties somehow arise from the \ordinary" physical realm) is plausible. Chisholm, as you might guess, rules out option (b) from the previous quote; he then arrives at a complete argument for the doctrine of simple souls, viz., Arg1 sound ! (a) _ (b); Arg1 sound ^ :(b). What rationale does Chisholm give for :(b)? Note, first, that, as Quinn (1997) seems to acknowledge, perhaps the only sort of formidable emergentism is one aligned with supervenience. Quinn appeals to a brand of supervenience due to Jaegwon Kim, defined as follows. 3There are certain disjunctive properties that have all five properties on this list, and they need to be excluded from the class of qualitative properties if qualitative properties are to attach to things that are capable of thinking. Certain conjunctive properties need to be excluded for similar reasons. Like Quinn (1997), I ignore these details, which are outside the focus of my paper. 2 (D1) A-properties supervene on B-properties =df Necessarily, for any object x and A-property a, if x has a, then there is a B-property b such that (i) x has b, and (ii) necessarily, if anything has b, it also has a. (Kim 1984, 165) The idea here would be that mental properties supervene on certain physical properties; such a scheme would lend credence to option (b). Chisholm's response is vintage Chisholm: If we take [this bolstering of (b)] seriously, then we should consider how we might go about applying it to some property that is quite obviously mental and not merely sensory. Let it be the property of concluding that it is about to rain. We should have at least one plausible version of how the explication might go. We would like to know, for example, how to complete the following thesis: (T) The mental property of concluding that it is about to rain supervenes upon the physical property of |. How are we to fill in the blank? At present, the only examples we have are make-believe, such as \The mental event supervenes on the Z excitation of the C-fibers," where one offers no real terms with which \Z excitations" and “C-fibers" might be replaced. Have there been any real attempts to answer this question? Or have there been any conflicting theories about what the answer might be? When we try to consider all the things that can influence one's mental life, doesn't it seem clear that the physical upon which any mental event depends would need to be put as an extraordinarily complex disjunctive property? One cannot help but wonder whether the finding of such a property would have to await the completion of the natural sciences. (Chisholm 1997: 69) Perhaps you find this line of defense to be at least somewhat successful.