Penultimate version of paper published in Faith and Philosophy 26:2 (2009) 186-204. NOT PROPERLY A PERSON: THE RATIONAL SOUL AND 'THOMISTIC SUBSTANCE DUALISM' Christina Van Dyke Abstract: Like Aristotle, Thomas Aquinas holds that the rational soul is the substantial form of the human body. In so doing, he takes himself to be rejecting a Platonic version of substance dualism; his criticisms, however, apply equally to a traditional understanding of Cartesian dualism. Aquinas's own peculiar brand of dualism is receiving increased attention from contemporary philosophers-especially those attracted to positions that fall between Cartesian substance dualism and reductive materialism. What Aquinas's own view amounts to, however, is subject to debate. Philosophers (such as J. P. Moreland and Scott Rae) have claimed that 'Thomistic substance dualism' (TSD) centers around two beliefs: 1) the rational soul is an immaterial substance, and 2) this immaterial substance is the human person. In this paper, I argue that labeling such an account 'Thomistic' proves dangerously misleading-not only does Aquinas himself explicitly deny both of these claims, but he denies them for philosophically significant reasons. Furthermore, I argue that Aquinas's own position provides an account of human nature both more coherent and philosophically attractive. In the ongoing debates among Christian philosophers concerning personal identity and human nature, there's increasing interest in Thomas Aquinas's position on the subject. This interest has been sparked in large part by the fact that Aquinas rejects traditional forms of both substance dualism and reductive materialism-a rejection that resonates with many contemporary philosophers who also want to carve out conceptual space between either accepting Platonic/Cartesian substance dualism or denying the existence of the soul. The project of getting clear on the details of Aquinas's view of the relation between soul and body, however, has gained a reputation in analytic circles as both difficult and frustrating.1 Thus, although an increasing number of philosophers recognize that Aquinas holds a position distinct from both substance dualism and reductive materialism, they often express confusion over the view itself and dismiss it in more or less short order. Hud Hudson, for instance, qualifies his claim that the vast majority of Christians have been dualists by quickly adding: "Or if not dualists, whatever it is that Aquinas is."2 This attitude more than any other, perhaps, epitomizes contemporary reactions to Aquinas's account of human nature.3 2 A notable exception to this general rule, however, is J.P. Moreland. Long a proponent of a Thomistic account of human nature,4 he argues in Body and Soul: Human Nature and the Crisis in Ethics (co-authored with Scott Rae) that Aquinas's position proves "both intellectually defensible and biblically based" (14).5 In fact, Moreland and Rae maintain that what they term 'Thomistic substance dualism' (TSD) provides us with a metaphysical account of human nature that in turn grounds a distinctive and highly plausible position in the current ethical debates surrounding abortion, fetal-tissue research, genetic technologies, and euthanasia.6 As such, they argue, Aquinas's position deserves serious consideration from contemporary ethicists as well as metaphysicians and philosophers of mind. I agree that the Thomistic account of human nature merits further attention from contemporary philosophers. Yet, as I show in this paper, Aquinas's actual position diverges radically from TSD; this divergence is important, moreover, because Aquinas's position proves more philosophically plausible than TSD. Moreland and Rae identify two claims as central to their theory, the first of which is that the rational soul is an immaterial substance. As they say, TSD "is not a dualism of two separable substances. There is only one substance...the soul, and the body is an ensouled biological and physical structure that depends on the soul for its existence" (201). TSD thus distinguishes itself from Cartesian substance dualism largely by denying that both body and soul are substances. Instead, on this account a human person is composed of only one substance-the soul. The second claim central to TSD is that this one substance is the human person. At the heart of TSD, then, lies the statement that "[H]uman persons are identical to immaterial substances, namely, to souls" (11). Aquinas himself, however, explicitly rejects both of these claims. In fact, his insistence that the human soul is not the human being (or human person) lies at the very heart of his metaphysics of human nature. Furthermore, his denial that the rational soul is a substance and his subsequent explanation of the unity of the form-matter composite gives the body a central role in his account in a way that, ironically, 'Thomistic substance dualism' does-and, as we'll see, can-not. In identifying both the human being and the human person with the form-matter composite, Aquinas advocates a position that grounds further accounts of the flourishing human life in the deep good of embodied existence7-a position that should prove of interest to Christian philosophers of all stripes. 3 I. Rational Souls and Individual Substances In characterizing their position as one consistent with the main tenets of Aquinas's thought, Moreland and Rae consciously place themselves in a tradition; they claim to be employing the TSD label in "widely accepted ways" (201), and they cite John Cooper, Peter Kreeft, and Ron Tacelli as contemporary adherents of this view.8 Moreland and Rae acknowledge that what they're calling 'Thomistic substance dualism' might not follow Aquinas's original account to the letter; nevertheless, they do believe that it captures the spirit of Aquinas's thought. "[W]e do not claim to offer a version [of philosophical-theological anthropology] that conforms to Aquinas's in all details," they write. "Still, our view shares enough of the important aspects of a Thomistic approach to warrant our using that label for that position" (10). Later, they add: "[W]e do believe that our use of [this label] accurately captures the spirit-and often the letter-of [Aquinas's thought]" (200).9 In particular, Moreland and Rae hold that TSD's main advantage over traditional forms of substance dualism is that it identifies not two substances- body and soul-in the metaphysical make-up of human beings, but only one: the rational soul, which animates the matter that constitutes the body. Aquinas clearly shares Moreland and Rae's concern with the essential unity of the human person; in particular, he explicitly rejects a standard version of substance dualism, claiming instead that a human being is composed of one and only one substance. As this section goes on to demonstrate, however, Aquinas also presents philosophical grounds for denying that the one substance relevant to an account of human nature is the rational soul. In the early thirteenth century, a full-blooded substance dualism was the standard solution to the problem of the body-soul relation.10 Both the body and the soul were typically considered substances in their own right: the body was seen as a substance in virtue of its possessing the substantial form of 'corporeity', and the rational soul was considered an immaterial substance on a par with intellective substances (such as angels).11 Aquinas, however, argues against this position. First, he worries that if the soul were a complete substance in its own right, it would have no real need of the body, thus raising (among other things) the problem of why an absolutely perfect God would have joined the soul to the body in the first place;12 second, he points out that the essential unity of the human being would be seriously undermined if both body and soul were independent substances.13 Aquinas endorses Aristotle's doctrine that every substance has a unique function; if the soul were itself a 4 substance, however, it would be able to perform its function apart from the body (and vice versa), making it hard to understand what either would gain by being united. In fact, Aquinas believes that if the soul can exist naturally apart from the body, it would actually be inappropriate for it to be joined to a material body, since material things are by nature inferior to immaterial things.14 Identifying both body and soul as independent substances also undermines the subsequent unity of body/soul composite; Aquinas argues, for instance, that Plato is wrong to think that the rational soul is a substance precisely because this would imply that the union of soul and body is nothing more than accidental.15 Rather than emphasizing the nobility of the rational soul (by stressing its independence from the body), then, Aquinas prefers to stress the intimate connection between body and soul inherent in the Aristotelian claim that the rational soul is the substantial form of the human body.16 As the body's substantial form, the human soul structures, organizes, and accounts for the continued biological processes of the entire human organism. The rational soul is not just responsible for abstract thought, in other words-it's also responsible for our toenails growing, our livers filtering toxins from our blood, and our hearing the alarm clock go off in the morning. Our bodies cannot function in separation from our souls. At the same time, however, our souls cannot function properly in separation from our bodies. Indeed, the body plays a vital role in carrying out the human function of intellective cognition: although the activity of intellection does not require union with matter per se-after all, God and angels are paradigmatically intellective-human intellection involves the activity of the bodily senses as well as the soul.17 As Aquinas points out, even the standard medieval definition of 'human being' as 'rational animal' includes reference to both the rational soul and matter.18 In his account of human nature, then, Aquinas focuses his attention on the composite of form and matter rather than on the form alone; he holds that the rational soul cannot have central importance in discussions of human nature because it is only one part of a human being. Aquinas makes the claim that the rational soul is not the one substance relevant to human nature in a number of places,19 but his most extended discussion of the topic takes place in the first of his Questions on the Soul (QDA)-a treatise aimed at clarifying the nature of the rational soul, as well as its relation to the human being, the human body, and God. Aquinas claims that the rational soul is the substantial form of the human being, but he also holds that it survives the death of the composite and that it exists in separation from matter at death and 5 prior to the bodily resurrection.20 As Aquinas himself realizes, however, this raises troubling questions about the status of the rational soul. Insofar as it can persist in separation from matter, the soul appears to be capable of independent existence. According to Aquinas's own metaphysical views, though, if the rational soul has independent existence, it also seems as though it should count as an individual substance. If the soul were an individual substance, however, and thus presumably already a member of its own species, it couldn't, together with the body, constitute a member of the human species.21 The question that Aquinas faces, then, is whether something can be capable of independent existence without also being a substance. Aquinas responds in the affirmative. In order for something to qualify as an individual substance in the sense relevant for an account of human nature (that is, for it to qualify as a hoc aliquid22), he claims that it must meet two conditions: it must be able to subsist per se and it must be a member itself of a particular species and genus. In his own words: "An individual in the genus of substance possesses not only per se subsistence, but is also something complete in a particular species and genus of substance" (QDA 1.co). For something-say, 'David'-to meet the conditions for being a particular substance (a hoc aliquid), David must be an entity capable of independent existence and must also satisfy the definition of a particular species-in this case, 'human being'-and a genus-in this case, 'animal'. This two-fold criterion is key for understanding the status of the rational soul, for Aquinas goes on to argue in this context that the human soul meets the "independent existence" condition for being a particular substance but that it fails to meet the "complete in species and genus" requirement. The soul counts as a particular substance only "insofar as it is able to subsist per se, not as if it belongs in itself to a complete species, but as it completes the human species as the form of the body" (added emphasis).23 Because intellective activity-the rational soul's proper act-is by nature independent of the body, the soul's "being" (its esse) is, in a crucial sense, also independent from the body.24 The rational soul is not, however, complete in species and genus in a way that would meet the second requirement. Aquinas claims, for instance, that Plato was mistaken in thinking that the rational soul contains the "full nature" of the species; instead, he argues that, although the human soul "is part of what is complete in species", it "is not complete in species per se" (ad 3 and 4).25 David's soul, in other words, is one part of the human being-in fact, it is the very part that accounts for its being a human in 6 the first place-but it isn't itself a rational animal. It can't, for instance, laugh, or breathe, or sneeze. Instead, the physical composite of David's substantial form and matter is what performs those activities: the composite is what satisfies the definition of 'human being' and 'animal'.26 This discussion seems to indicate rather strongly that Aquinas believes that the one substance relevant to an account of human nature is the composite of form and matter, rather than the rational soul. Yet, on Moreland and Rae's 'Thomistic substance dualism', "the one substance is the soul, and the body is an ensouled biological and physical structure that depends on the soul for its existence" (201). In the following section, I ward off objections that this conflict is only apparent, or merely the result of two different understandings of 'substance', with a closer examination of Moreland and Rae's explicit claims about the nature of substance and the role it plays in TSD. Despite their own intentions, I believe that Moreland and Rae's emphasis on the soul's status as a substance departs rather radically from Aquinas's own view; in particular, I believe that this emphasis ultimately renders the body's role in an account of human nature extraneous. II. The "Traditional View of Substance" and the Rational Soul In discussing and defending what they call the 'traditional view' of substance (70), Moreland and Rae present seven necessary attributes for something's being a substance: 1) basic ownership of properties, 2) unity and wholeness at a time, 3) identity and sameness through change, 4) law and lawlike change, 5) the unity of the natural kind itself, 6) final causality, and 7) individuation.27 They then claim that, according to TSD, it is the human soul rather than the body-soul composite that possesses these attributes and meets the conditions for 'substancehood'. In this section, however, I argue that an examination of Aquinas's own views on the nature of just four of these attributes (namely, basic ownership of properties, unity and wholeness at a time, individuation, and final causality) demonstrates clearly enough for our purposes that Aquinas identifies the matter-form composite and not the soul as a substance in Moreland and Rae's sense-and, furthermore, that he is right to do so. Moreland and Rae begin their list of the criteria for 'substance-hood' with "basic ownership of properties." In their own words: "Substances have properties that are 'in' them; properties are had by the substances that possess them" (70). Thus, if the rational soul is the 7 one substance at stake in discussions of human nature, the soul is the substance that possesses the properties of a human being. David's kindness, for example, is a property that inheres in his rational soul, as is his ability to multiply or add fractions. Although it makes a certain amount of sense to claim that David's mathematical skill is a property that inheres in his soul, it's not clear how properties typically associated with his physical body (such as height, weight, and hair color) could properly be attributed to his soul. How, for instance, can the blueness associated with David's eyes meaningfully be said to inhere in his rational soul-as opposed to, say, inhering in his living body? Claiming that the blueness inheres in a "physical structure dependent on the soul" is, after all, not the same as claiming that such blueness inheres in David's soul itself. The same problem arises for all of the properties typically associated with David's physical body. At best, it seems that David's soul would possess those properties derivatively or in virtue of his body's possessing them- surely not something that bolsters the soul's claim to being a substance. One could, perhaps, argue that the soul has basic ownership of all the properties of a human being simply by dint of being the only sort of thing in the ontological neighborhood that could possess such properties (it has independent existence, say, while the body is dependent for its existence on the soul), but that tack seems merely to beg the very question at issue. Indeed, this difficulty neatly illustrates one of the central problems facing TSD: namely, that its attempt to present a unified account of human nature by positing just one substance (rather than two) in the human being is undermined by its identification of the rational soul as the one relevant substance in such an account. The apparent difference between mental and physical properties is one of the main considerations that leads Descartes, among others, to posit the existence of both an immaterial and a material substance in the human being in the first place, with mental properties inhering in the immaterial substance (soul), and physical properties inhering in the physical substance (body). In claiming that there is but one substance present in the human being and then identifying that substance with the immaterial soul rather than the composite, TSD appears to offer an implausible (or question-begging) subject of inherence for physical properties. In contrast, Aquinas himself argues explicitly that the living body-the matter-form composite-is the one substance relevant to an account of human nature, and that it possesses both physical and mental properties.28 The blueness of David's eyes is, according to him, a 8 property that inheres in the ensouled body that is David. As we saw above, the rational soul is only one part of the human substance. Aquinas takes this claim very seriously: even the rational soul's characteristic activity-namely, intellective cognition-requires the body's participation, absent divine intervention.29 The composite human being (and not the rational soul) is, thus, what's properly responsible for actions such as understanding and perceiving. As Aquinas himself writes: "It can be said that the soul understands...but it is said more properly that the human being understands through the soul" (ST Ia.75.2.ad2).30 Furthermore, the soul alone cannot properly be praised or blamed for the goodness or badness of human actions;31 the sin of anger, for example, is committed not by the rational soul, but by the composite of form and matter. This is, in fact, one of Aquinas's arguments for the necessity of the bodily resurrection: because it was the composite human being who sinned or acted well, corresponding punishment or reward would be incomplete if it involved the soul alone.32 From his understanding of the concept of a triangle to the size of his feet, David's properties inhere in the living compound of matter and form that is David. It might seem counter-intuitive to claim that an account which posits a substance composed of matter and form is more genuinely holistic than an account which posits only a non-composite substance. An examination of how these two accounts fare with respect to Moreland and Rae's second criterion for substance-hood-namely, metaphysical priority and unity-yields further support for this claim, however. Moreland and Rae characterize this criterion as follows: "[A] substance is a primitive unity of properties, parts and capacities. Moreover, the type of unity in a substance is to be explained by seeing the substance as a whole that is metaphysically prior to its parts in that the parts get their identity by the role they play in the substance as a whole" (73). That is, a substance can possess parts-but any parts that exist in that substance must depend on it for their identity, function, and so on. According to TSD, the rational soul is what plays this unifying role for the human being. That is, the soul is metaphysically prior to the soul-body composite and all its parts; as the human being's substantial form, the soul accounts for the human being's physical structure, its capacities, etc. Because the rational soul is responsible for both structuring and maintaining the life-processes of the physical organism, it seems plausible to suppose that the soul would be metaphysically prior to that organism. 9 When examined more closely, however, this view appears to commit TSD to the highly unintuitive claim that the human body is a proper part of the rational soul. If the human being is identical to the substance that is the rational soul (as Moreland and Rae explicitly claim), then either the human body is not part of the human substance, or the human body is a part of the human being-a part that "gets its identity" by the role it plays in the substance as a whole, in which case the human body is, properly speaking, a part of the substance that is the rational soul. Clearly, given the emphasis that TSD is meant to place on embodied experience, TSD would reject the possibility that the human body is not part of the human substance (being instead either a substance in its own right or a non-substantial collection of accidents or elements). That leaves only the possibility that the human body must, in some way, be a proper part of the rational soul. Although Moreland and Rae might be willing to bite this metaphysical bullet, it seems a heavy price to pay for a unified account of human nature-especially given that they explicitly and consistently identify the rational soul as an immaterial substance.33 Accepting that the human body is a proper part of the rational soul for the sake of a holistic account of human nature appears even more unpalatable in light of the fact that Aquinas himself provides an alternate explanation for how the composite human substance can constitute a "primitive unity" that is metaphysically prior to its parts-both matter and form. As we've already seen, Aquinas claims that the human soul is one part of the human being, not the human being itself. Moreover, in his commentary on the famous resurrection passage in I Corinthians 15, Aquinas even refers to the human soul as one part of the human body (where he's taking the body to be the already-existing composite of matter and form): "Since the soul is part of the human body, it is not the whole human being," he writes, "And I am not my soul."34 This seems to indicate rather strongly that Aquinas sees soul and matter as proper parts of the living human substance.35 Certainly, on his view, they are not ontologically prior to the composite, for the individual rational soul begins to exist only when the composite comes into being. God infuses the substantial form 'human being' into an already-existing fetal body, at which point both the individual rational soul and the particular human body come into existence. Thus, both parts of the matter-form composite begin to exist at the very moment that the composite substance itself begins to exist. Even God could not create multiple human souls apart from matter, Aquinas argues, or actual bodies apart from form. Since human souls are all 10 particular instances of the universal substantial form 'human being', without reference to matter there would be nothing to distinguish one soul from another.36 In turn, since matter is, by nature, potentiality, material beings are dependent on substantial forms for their actual being. On Aquinas's view, then, it does appear that the form-matter composite, rather than the rational soul, is the "whole that is metaphysically prior to its parts," since those parts- particular souls and individual bodies-"get their identity by the role they play in the substance as a whole." The rational soul is indeed responsible for organizing, structuring, and vivifying the human physical organism, but that organism's existence is the necessary ontological and conceptual precondition for that soul's possessing and carrying out the particular functions and processes that it does. The form-matter composite also appears to comprise a "primitive unity" in Moreland and Rae's sense, insofar as it grounds all the properties, capacities, and activities of the human being. In this way, the human composite of form and matter constitutes a fundamental unity that is metaphysically prior to both the body and the individual rational soul.37 The careful reader may have noticed that this discussion of unity also pertains directly to the seventh criterion for substance-hood, namely 'individuation'. Moreland and Rae raise the following question: "If Smith and Jones have the very same human nature, then how are they different? What makes them two humans instead of one?" (77). Their answer is that the rational soul possesses an inherent, individual "thisness" that distinguishes it from all other souls; it is "a universal nature related by predication to an individuating component" (78). Yet Moreland and Rae do not identify what this "individuating component" is. Indeed, I believe that on a hylomorphic theory they cannot identify this component in a non question-begging way, at least without appeal to matter. Such an appeal is blocked, however, by their insistence that the soul possesses the attribute of individuation. If the body were essential for individuating either the rational soul or the human being, the soul's claim to substance-hood would be compromised. Moreland and Rae might well respond that the soul's individuating capacity is simply a brute fact about it; the soul just is a bare particular. Although, generally speaking, this claim is perfectly intelligible, it again downplays the body's role in human nature-a consequence which, as we'll see, has deeply negative effects for a holistic account of human nature. 11 In addition, the claim that the soul individuates the human being directly conflicts with Aquinas's own stated view and further weakens the rationale for calling this position "Thomistic" substance dualism. Aquinas himself flatly rejects the possibility of each soul's possessing a unique haecceitas on the grounds that the substantial form 'human being' is by nature a universal; particularity can, so to speak, "come to it" only from outside itself. It is for this reason that Aquinas identifies matter as the principle of inter-specific individuation for all corporeal creatures, including human beings. Substantial form lacks any inherent "thisness", whereas matter by nature distinguishes one thing from another and entails that they occupy unique spatio-temporal locations.38 Although Aquinas's theory of individuation is notoriously complex, I've argued elsewhere that it is both coherent and defensible.39 In fact, the complications that arise for his theory stem from the very ways in which soul and body depend on each other-a fact which only underscores the unity of the human substance. An examination of one final criterion for substance-hood, "final causality", is sufficient, I believe, to demonstrate conclusively not only that Aquinas does not identify the rational soul as a substance on this seven-fold list of attributes, but also that his rejection of that possibility in favor of the form-matter composite renders his theory more philosophically attractive than TSD. Moreland and Rae summarize the idea of final causality as follows: "Many advocates of the traditional view [of substance] hold that an individual substance has, within its nature (formal cause), an innate, immanent tendency (final cause) to realize fully that nature...When a part or process of a living thing functions naturally, it functions the way it ought to function, that is, in the way appropriately specified by its nature" (75). Most advocates of the Aristotelian view of the four causes, of course, also talk about final causality in terms of teleology-the "end" or purpose of that substance. Here we enter some deep hylomorphic waters. To clarify precisely how final causality is meant to be an attribute of a substance, it helps to return to our example. The idea, as Moreland and Rae characterize it, is that David has a nature-'human being'-which is his formal cause, or substantial form. David's final cause is seen, in turn, as an "innate, immanent tendency" to actualize that nature. TSD thus appears to equate actualizing human nature with actualizing the rational soul. 12 The problem that TSD faces here again involves the unity of the human being. On this view, the human soul is integrally related to its essence or nature. In their words: "Now the individual soul is constituted by a human essence...On this view, the organism or soul is a whole that is ontologically prior to its parts-in this case, its body" (206). I've discussed the question of ontological priority above; the new component here is the issue of the "human essence."40 In their discussion of another criterion for substance ("unity of the natural kind itself"), Moreland and Rae clarify somewhat what they mean by this term: "Substances fall into natural classes called natural kinds (e.g., the class of dogs, humans and so forth). This can be explained by saying that each member of a natural kind has the very same essence in it" (75).41 These natural kinds are what Aquinas refers to as species; each member of a species or natural kind has the same essence, since possession of that essence is what accounts for their membership in that species in the first place. TSD's claim that the rational soul is constituted by the human essence (plus, as we saw earlier, an 'individuating component') and ontologically prior to the body allows for the further claim that the disembodied post-mortem soul is, in essence, a human being even without one of its primary parts-namely, the body. This view has the prima facie advantage of providing a neat account of post-mortem identity. It entails, for instance, that the human being does not cease to exist at death, despite the separation of soul from body. In so doing, however, this view seems to open itself to precisely the sort of worries concerning the marginality of the body that are supposed to motivate TSD as a positive alternative to Cartesian substance dualism in the first place. The claim that the body is not a substance in its own right, but rather "an ensouled biological and physical structure that depends on the soul for its existence" (201) doesn't, when combined with the claim that the human being can survive its loss, provide a holistic account of human nature that celebrates the good of embodied existence so much as it diminishes the body's role in that account to near-insignificance. At best, it appears, TSD entails that the soul-the human person on this account-has a natural inclination to inform a body, albeit an inclination that does not have to be realized in order for the person to exist. To put the point more clearly, the body itself is not essential to human nature on TSD; rather, what's essential is that the soul have an inclination to inform a body. Although Aquinas agrees that substances fall into natural kinds and that each member of a natural kind has the very same essence, he doesn't (as we saw in section I) believe that the 13 soul itself either constitutes or is constituted by that essence, for the soul is not in itself 'complete in species and genus'. Instead, as Aquinas comments in De ente et essentia, he takes the word 'essence' to signify "that which is composed of matter and form" (2.5).42 To use Moreland and Rae's language, Aquinas holds that a human being is, in essence, a physical creature: what is it to be human involves matter as well as form. To return to the question of final causality, then, although Aquinas would agree wholeheartedly with the claim that individual substances have an innate and immanent tendency to realize their nature-and he would even agree that the formal cause of an individual substance accounts for the function of that substance-he would not identify the formal cause of an individual (e.g., the substantial form of a human being) with that individual substance (e.g. the individual human being). David's rational soul accounts for his functioning as a rational animal, but that rational animal, David, is necessarily a composite of soul and matter. An account of what it means for David to actualize his human potentialities, then, and to flourish as a human being will necessarily include reference to his body as well as to his soul. David will not exist, in essence, when his soul separates from his body at death. Rather, death causes a rupture in human identity that only the bodily resurrection can repair.43 In general, Moreland and Rae are right, I believe, to claim that: "...the Thomist will insist on a more deep, intimate relationship between soul and body than the mere causal connection between a Cartesian mind and a solely physical body" (201). Nevertheless, TSD appears consistently to downplay the role of the human body in comparison to Aquinas's own view, which repeatedly stresses the importance of both the immaterial and material aspects of human nature. In this section, I have argued that this understatement is to the detriment of TSD: TSD might bring body and soul closer together than a traditional form of Cartesian dualism does, but it fails to account adequately for the unified nature of the physical human being. III. The Human Person and the Rational Soul So far, this paper has focused on the first of the two claims central to TSD (namely, that in the human being, "There is only one substance...the soul, and the body is an ensouled biological and physical structure that depends on the soul for its existence" [201]), distinguishing between this claim and Aquinas's own position on the soul, and arguing that Aquinas holds the more 14 philosophically plausible view. I want now to conclude this paper with a much briefer examination of TSD's second main claim: namely, that "human persons are identical to immaterial substances, namely, to souls" (11). Given the groundwork laid out in the previous two sections, it should come as no shock that Aquinas rejects this claim as well. The prominence of the concept of 'person' in contemporary philosophical debates concerning human nature, identity, and a variety of issues in ethics, however, makes it worthwhile to establish conclusively that Aquinas identifies the human person, as well as the human being, with the living compound of form and matter and not with the immaterial rational soul.44 To see this, it helps to begin with a look at how Aquinas understands the concept of 'person', for Moreland and Rae also advocate this characterization. Aquinas discusses the meaning and application of the term 'person' in several places (most notably, ST Ia29 and Questiones De potentia 9.2), always providing and endorsing the traditional Boethian definition of 'person' as "an individual substance with a rational nature" (rationalis naturae individua substantia).45 As he is quick to point out, this definition applies to human beings, angels, and God. God and the angels differ from human beings in being immaterial, however. Because God sets the standard for person-hood, this then raises the question of whether immateriality is one of the necessary features of person-hood. Moreland and Rae, who also endorse Boethius's definition of 'person', suggest that it is: "If God and, perhaps, angels, are paradigm-case persons and since they are immaterial spirits, then it is at least consistent that something be both a person and an immaterial spirit. But more than this, if the paradigm-case persons are immaterial spirits, then this provides justification for the claim that anything is a person if and only if it bears a relevant similarity to the paradigm cases" (25). The human soul is immaterial-and, obviously, rational-and so one might suppose that it would make a better candidate for being a person than the form-matter composite.46 Moreland and Rae go on, explaining that: "Personhood is constituted by a set of ultimate capacities of thought, belief, sensation, emotion, volition, desire, intentionality and so forth. As we will argue later in the book, none of these ultimate capacities is physical, and therefore neither is personhood itself...[H]uman persons qua persons are immaterial substances and not material ones" (25). Indeed, later in the book they recast Boethuis's defintion of 'person' as "immaterial substances with a rational nature" (157). 15 Does Aquinas identify the rational soul as a person, even though he denies that it is the human being? There is, certainly, philosophical precedent for the idea that the person might not be identical to the human physical organism.47 This intuition is commonly primed by cases involving higher-order brain death and persistent vegetative states, where it seems that organic life persists in the absence of the capacity for rationality. Although TSD wouldn't make this distinction, since it identifies the human organic substance with the rational soul, it's an interesting question whether Aquinas would-since, in this case, he would be in agreement with TSD with respect to one of its two central claims. To that end, it is worth noting that the definition of 'person' as an "individual substance with a rational nature" doesn't itself rule out the possibility that the soul is a person on Aquinas's account. First, insofar as it is called the rational soul, the human substantial form obviously possesses a rational nature. Second, as we saw in section I, Aquinas believes that the rational soul does meet one of the two criteria for being an individual substance-namely, the capacity for independent existence. Although only things which also satisfy the definition of a genus and species count as individual substances in the strict sense, Aquinas identifies a looser sense in which even things like amputated hands and feet can be called particular substances, and he does often refer to the human soul as substance in this sense.48 Thus, if Aquinas intends the definition of 'person' to apply broadly to any kind of substance that also possesses a rational nature, then the rational soul will count as a person, given that it is an individual in the genus of substance in the broad sense of 'substance'.49 There is at least one passage in which Aquinas seems to appeal to this line of thought: in ST 29.1.ad3, he writes that "the term 'individual' is placed in the definition of 'person' to designate the mode of subsisting which belongs to particular substances". Since Aquinas holds that the rational soul possesses the capacity for subsistence, if his focus on the individuality of persons concerns subsistence to the exclusion of being complete in species and genus, rational souls could count as persons. This rather thin possibility is ruled out almost immediately, however, by further discussions in both ST Ia.29.1 and QDP 9.2 in which Aquinas explicitly considers-and denies-the claim that the rational soul is "an individual substance with a rational nature" and should, thus, be considered a person. In ST Ia.29.1.ad5, for example, Aquinas responds to this claim as follows: "[T]he soul is part of the human species; for this reason, since it is still by 16 nature unitable [to a body] even when it is separated, it cannot be the sort of individual substance which is called a "hypostasis" or "first substance" any more than a hand or any other part of a human being can. And so neither the name nor the definition of 'person' belongs to the rational soul". This response follows the same line of thought that we saw in section I: since the rational soul is only one part of the human species, it doesn't meet the conditions for being the relevant sort of individual substance ('hypostasis', 'first substance' or 'hoc aliquid'), and so it can't be a person. Again, in QDP 9.2, Aquinas writes that "the separated soul is part of [something with] a rational nature, namely, human [nature], but it is not the whole of rational human nature, and therefore it is not a person" (ad14). On the other hand, the human matter-form composite does satisfy the definition of 'person' (in all cases but that of the incarnate Christ).50 As Aquinas puts it, in the case of human beings, the word "person" dennotes "this flesh and these bones and this soul, which are the principles that individuate a human being, and indeed which, although they don't belong to the signification of 'person', do belong to the signification of 'human person' (humanae personae)" (4.co). That is, although material components such as flesh and bones are not part of the general signification of 'person' (as, for instance, when the person in question is an angel), the term "human person" signifies all the necessary components of an individual human being-including the material components, for, as we saw above, Aquinas includes matter as well as form in the essence of a human being. For Aquinas as well as Moreland and Rae, then, the human person is ordinarily identical to the human being.51 Moreland and Rae identify both human person and human being with the immaterial rational soul, however, whereas Aquinas identifies both human person and human being with the composite of form and matter.52 Aquinas's metaphysics is grounded on claims about the essential natures of genera and species. If David exists as a substance, David exists as a substance within a particular genus and species-in this particular case, David exists as a human being, a composite of matter and form. Thus, if David is a person, and a person is an individual substance with a rational nature, that rational substance will be identical to the composite of form and matter that is David. Even if there is a close connection (as Aquinas believes there is) between rationality and immateriality, then, Aquinas himself holds that the concept 'person' does not itself entail immateriality. 17 In conclusion, it seems clear that Aquinas himself rejects both of the central claims of 'Thomistic substance dualism'-he denies both that the rational soul is a substance and that the rational soul is the human person. The prominence in Christian (or, at least, Protestant) philosophical circles of J.P. Moreland's version of Thomism makes this significant in its own right, I believe. Despite their intention to present an account of human nature that conforms to the general spirit, if not the letter, of Aquinas's own theory, Moreland and Rae present a position that diverges from the most basic features of his metaphysics. At the same time, as I argued in section II, Aquinas himself appears to offer a more philosophically attractive account of human nature. In identifying the rational soul as the one substance at stake in discussions of human nature, Moreland and Rae's TSD consistently downplays the role of the body in its 'holistic' account. Although it may draw a tighter connection between body and soul than does a traditional version of Cartesian substance dualism, TSD does so at the cost of excluding physicality almost entirely from what it means to be human. As we've seen, it is to its own detriment that TSD refrains from going as far as Aquinas does in providing a unified account of human nature. Given that Moreland and Rae advocate TSD in part because they feel that traditional substance dualism places too little emphasis on the living physical organism, this seems especially ironic. In identifying the matter-form composite (and not the soul) with the human being and the human person, Aquinas offers a radically unified account of human nature that celebrates the good of embodied existence while not reducing human beings to matter.53 It's precisely this emphasis on the unity of form and matter that motivate Moreland and Rae to advocate TSD-and it's precisely this emphasis that should make Aquinas's own account more attractive than TSD to those contemporary philosophers who also find themselves unconvinced by Cartesian dualism and unwilling to accept a purely physicalist account of persons.54 Calvin College NOTES 1 Even the question of what to call his position has proved complicated. In Aquinas, for example, Eleonore Stump proposes calling his position "subsistence dualism," a version of 18 non-reductive materialism (New York: Routledge, 2003), 212. Stump's final conclusion, however, is that the real lesson to be learned from a close examination of Aquinas's account of human nature is "that it is a mistake to suppose that one must choose between materialism and dualism" (215). 2 A Materialist Metaphysics of the Human Person (Ithaca: Cornell University Press, 2001), 168, ftn. 2. 3 This confusion persists despite a recent spate of books devoted to clarifying and defending Aquinas's account of human nature within the analytic tradition, including Eleonore Stump, Aquinas (2003) and Robert Pasnau, Thomas Aquinas on Human Nature: A Philosophical Study of Summa theologiae Ia 75-89 (Cambridge: Cambridge University Press, 2002). 4 See, for example, his paper with Stan Wallace, "Aquinas versus Locke and Descartes on the Human Person and End-of-Life Ethics," International Philosophical Quarterly 35 (1995), 319330. 5 J.P. Moreland and Scott Rae, Body and Soul: Human Nature and the Crisis in Ethics (Downers Grove: InterVarsity Press, 2000). 6 For an argument against Moreland and Rae's claim that a Thomistic substance dualism entails one particular ethical stance over others, see Kevin Corcoran, "Material Persons, Immaterial Souls and an Ethic of Life," Faith and Philosophy 20 (2003), 218-228. 7 For an extended argument to this effect, see Rebecca DeYoung, Colleen McCluskey, and Christina Van Dyke, Aquinas's Ethics: Metaphysical Foundations, Moral Theory, and Theological Context (Notre Dame, IN: University of Notre Dame Press, forthcoming). 8 It's not clear that the scholars cited would be altogether pleased with this label. See John W. Cooper, Body, Soul, and Life Everlasting (Grand Rapids: Eerdmans, 1989) and Peter Kreeft 19 and Ron Tacelli, Handbook of Christian Apologetics (Downers Grove: InterVarsity Press, 1994). 9 The brackets are a function of my omitting reference to Descartes; Moreland and Rae contrast Cartesian substance dualism with Thomistic substance dualism, and make the same general claim about the relation between Descartes's original views and CSD as they do between Aquinas's views and TSD. I'm interested only in discussing Aquinas in this paper. 10 See Richard C. Dales, The Problem of the Rational Soul in the Thirteenth Century (Leiden: Brill, 1995) for a detailed overview of the people who argued for such a position. 11 For Aquinas's discussion of and rejection of this possibility, see, e.g., Summa contra gentiles [SCG] IV.81. For a detailed discussion of these issues in the secondary literature, see Anton Pegis, Saint Thomas and the Problem of the Rational Soul in the Thirteenth Century (Toronto: Pontifical Institute of Mediaeval Studies, 1934), 26-76. 12 Further, he worries that there would then need to be something else that joins the soul to the body. In Questions on the Soul [QDA] 9.co, for instance, Aquinas claims that "diverse and distinct substances cannot be joined together (colligantur) unless there is something that unites them." See also On Spiritual Creatures [DSC] 3, SCG II.71, and Summa theologiae [ST] Ia.76.6. 13 See, e.g. ST Ia.118.3.co and SCG II.69. 14 This claim about the inferiority of material things derives in part from Aquinas's hierarchy of being, which has its pinnacle God-pure actuality-and as its lowest endpoint prime matter-pure potentiality. Material things are inferior to spiritual or immaterial things because they possess more potentiality, and are, hence, farther from God on the hierarchy. 20 15 For extended versions of Aquinas's criticism of Plato's account of human nature, see DSC 2, as well as QDA 1.co and 11.co. 16 Aquinas discusses his reasons for adopting Aristotle's view at length in ST Ia76.1. See also DSC 2. 17 In separation from matter (after death and prior to the bodily resurrection), the soul actually has a different mode of cognition that requires divine assistance. (See, e.g., ST Ia.89.1 and On Truth [DV] 19.1.) The claim that the soul cognizes in separation from matter appears to raise serious problems for Aquinas's account of human identity through death and the resurrection. (For a discussion of these problems, see my ****.) 18 See, e.g., DEE 2, in which Aquinas discusses why the definition of human being requires reference to both material body and rational soul. 19 See, e.g., ST Ia 29.1.ad5, ST Ia 75.ad2, and Questions on Power [QDP] 9.2. 20 The Treatise on Human Nature (ST Ia.75-89) provides perhaps the most famous discussion of this topic. Robert Pasnau provides a very helpful commentary on this discussion together with his translation; see Treatise on Human Nature: Summa Theologiae Ia 75-89 (Indianapolis: Hackett, 2002). 21 The third objection to QDA 1 poses the problem as follows: "If the soul is a hoc aliquid, it follows that it is a particular individual. Every individual is in a particular species and in a particular genus, however. As a result, the soul would have a proper species and a proper genus. It is impossible that something having a proper species could receive something else added (superadditionem) to it for the constitution of the same species...However, matter and form are joined for the constitution of [the human] species. Therefore, if the soul is a hoc aliquid, it is not joined to the body as form to matter" (QDA 1.obj 3). 21 22 Literally 'this something', the phrase 'hoc aliquid' is consistently used by Aquinas as the technical term for what Aristotle refers to as a tode ti, or a particular substance. 23 In this looser sense, the human soul does count as a substance, and so whether or not Aquinas himself considers the rational soul a substance appears to depend on whether he is speaking more or less technically. This qualification also helps explain why Aquinas sometimes calls the rational soul a substance while in other contexts explicitly denying that it is one. When Aquinas refers to the soul as a substance, he's using the term in the broad-rather than the technical-sense. Aquinas breaks the category of creatures into two general groups: intellective and non-intellective substances; given this division, a discussion of the rational soul clearly belongs in the discussion of intellective substances, even if the soul does not technically meet both of the necessary conditions for substance-hood. Moreover, even in this context, Aquinas is careful to point out that the human soul isn't a substance in the fullest sense of the term. At the beginning of SCG II.69, e.g., Aquinas resolves an earlier objection (viz. that two actually existing substances-the soul and the body-cannot constitute a unity) by claiming that "the soul and the body are not two actually existing substances, but from these two things one actually existing substance is made". 24 "An intellective soul must act per se, as something that has a proper operation apart from union with the body. And since anything acts insofar as it is in actuality, the intellective soul must have absolute being (esse) per se, not depending on the body" (QDA 1.co). This claim about the soul's intellective operation not requiring the body does not actually conflict with Aquinas's belief that the body is needed for human cognition. Aquinas's theory of human cognition is extremely complex; in short, the physical senses provide sense data which the inner sense employs in making phantasms, from which the intellect can abstract universal, 22 'intelligible species'. The intellect's proper operation involves the contemplation of these abstract intelligible species-contemplation which could occur apart from matter (as it does in the case of angels and God). In the case of human beings, however, the intellect requires the body to get to this stage of operation, and also needs to turn back to the phantasms each time it cognizes. For detailed discussions of Aquinas's theory of cognition, see Scott MacDonald's "Theory of Knowledge," in the Cambridge Companion to Aquinas, ed. N. Kretzmann and E. Stump (Cambridge: Cambridge University Press, 1993), 160-195 and Pasnau, Thomas Aquinas on Human Nature, chapters 9-11. 25 See also ST 75.7.ad3, where Aquinas writes: "Properly speaking, it is not the soul but the composite [of soul and body] that belongs to the [human] species." 26 David's soul is what accounts for his belonging to a particular genus and species, however: it is what explains why David breathes and sneezes. This constitutes an important difference between the way in which David's soul fails to satisfy the "completeness" requirement and the way in which David's amputated hand (which also possesses a certain kind of independent existence) fails to meet that requirement. Neither David's soul nor his hand is itself a member of the human species, but as his substantial form, David's soul plays a special role in his being human. 27 They discuss these seven attributes in some detail; see pp. 70-8 of chapter two. 28 See, e.g., chapter 7 of DEE, which amounts to a short treatise on the ontological status of accidental properties. Although Aquinas claims that some accidents "come from" the side of matter and that others "come from" the side of form, he is clear that the proper subject of all those accidents is the form-matter composite, as opposed to either the form or matter itself. 23 29 Thus, although the human soul exists in separation from matter at death and prior to the bodily resurrection, it can engage in intellective cognition in that state only through the mediation of God and/or the angels. See, e.g., ST Ia.89. 30 "Potest igitur dici quod anima intelligit...sed magis proprie dicitur quod homo intelligat per animam." 31 See, e.g., SCG IV.79.4137, Commentary on First Corinthians 15 lectio 2, and the Compendium of Theology 151-4. 32 See, e.g., SCG IV.79. 33 Independent evidence for thinking that Moreland and Rae see the human body as a proper part of the rational soul comes from their claim (which I discuss in more detail below) that: "On this view, the organism or soul is a whole that is ontologically prior to its parts-in this case, its body" (206). 34 "Anima autem cum sit pars corporis hominis, non est totus homo, et anima mea non est ego." 35 As he puts it: "the soul and the body are not two actually existing substances, but from these two things one actually existing substance is made" (SCG II.69). 36 As he writes in De ente et essentia: "...the individuation of [the human soul] depends on the body for its occasion, [i.e.] for its beginning, since it acquires individuated being only in the body of which it is the actuality" (5.31). See DSC 9.ad3 for a parallel passage. 37 It's worth noting in this connection that Aquinas's view concerning the metaphysical priority of the soul-body composite prevents him from claiming that, in the very special case of the Incarnation, Christ could not simply assume a human body without also assuming a created human soul. See, e.g., ST IIIa.2.5 and SCG IV.43 (3807). 24 38 The belief that substantial forms, which are common to all members of a species, cannot be individuated without reference to matter leads Aquinas to claim that angels-immaterial substances-can exist only one per species, since there is nothing in the nature of a substantial form which could distinguish one angel from another. 39 See Metaphysical Amphibians: Aquinas on the Individuation and Identity of Human Beings (Ph.D. dissertation: Cornell University, 2000). The story becomes especially complicated because matter as such-prime matter-is nothing but pure potentiality, and so what individuates one physical substance from another must be matter with some sort of actuality, what Aquinas calls in some places "signate matter" and in other "matter under interminate dimensions". 40 The casual equation of the organism with the soul here seems deeply puzzling, given not just that Moreland and Rae identify the soul as an immaterial substance, but also that they hold that the soul can persist in separation from the body after death-in which state it possesses neither organs nor organic life-processes and seems, therefore, not to be an organism in any normal sense of the term. 41 They go on to describe an essence as "the set of properties the thing possesses such that it must have this set to be a member of the kind and that if it loses any of its essential properties, it ceases to exist" (75). 42 "...significet illud quod est ex materia et forma compositum" 43 For a defense of Aquinas's account of post-resurrection identity, see my "Human Identity, Immanent Causal Relations, and the Principle of Non-Repeatability: Thomas Aquinas on the Bodily Resurrection," Religious Studies 43 (2007) 373-9. 25 44 It is important to note at the outset of this discussion that the general claims I make throughout this section about human persons need to be qualified when it comes to the completely unique case of the incarnate Christ. Aquinas is, himself, careful to point out that Christ is one and only one person, existing from eternity; there is not another person who comes to be when Christ assumes a human substantial form and matter-there is only one person, who is composed at the Incarnation of human substantial form, body, and the divine nature. Aquinas is also clear that this is a special case that applies only to the second person of the Trinity, and that the answer to the question of how Christ's human nature is joined to his divine nature is a mystery. See, e.g., his discussions in ST IIIa.2, CT I c.209, SCG IV 41-8, and De unione verbi incarnati. For a detailed discussion of the metaphysics of the Incarnation that focuses heavily on just these issues, see chapter 14 of Stump's Aquinas. 45 See also Commentary on Peter Lombard's Sentences I.23-5. 46 Someone who wished to push this line would presumably also draw parallels between the immateriality and the uniquely intellectual nature of God, angels, and the rational soul-a connection Aquinas himself stresses in Quodlibetal Questions [QQ] 3.8, ST Ia.75.5, SCG II.50, QDA 6, and DCS 1. 47 This distinction is often drawn by advocates of the constitution relation. See, e.g., Lynne Rudder Baker, Persons and Bodies: A Constitution View (Cambridge University Press: Cambridge, 2000). 48 See, e.g., the preface to the Treatise on Human Nature, where Aquinas refers to the human being as a composite of a corporeal substance, the body, and an immaterial substance, the soul. In his discussion of rational creatures in SCG II, he also frequently calls the human soul a substance, taken in this loose sense. (It's easy to see that he isn't using 'substance' here in a 26 technical sense, since the body has no claim to substance-hood on either of the criteria he lays out in QDA 1.) 49 And, in this way, the other members of the broader class of particular substances, such as hands and feet, would be ruled out of contention for being persons because they lack a rational nature. 50 See note 44 above. 51 In fact, Aquinas appears determined to make his definitions of "human person" and "human being" mirror each other in such a way that the terms could be used interchangeably, although, of course, they'd appear in different contexts. 52 Copelston, in fact, appears simply to equate Aquinas's view of the human being with his view of the human person when he writes in Aquinas (absent any discussion of the term "person") that: "it follows from the doctrine that the soul is naturally the form of the body that in its state of separation between death and the resurrection it is not in its natural condition and that it is not strictly a human person, since the word 'person' signifies the whole composite substance, the unity of soul and body" (London: Penguin Books, 1991), 170. 53 In fact, it's an account that motivates philosophical arguments for the resurrection of the body. See SCG IV.79-81. 54 Many thanks to the participants of the Fifth Annual Midwestern Conference in Medieval Philosophy and to my colleagues in the Philosophy Department at Calvin College for their helpful comments on this paper, and special thanks to Hud Hudson-both for his valuable philosophical feedback and for his not minding being used as an example of someone who has, in the past, glossed over Aquinas without bothering to figure out what he actually thought.