Was Aquinas a dualist?
At the start of chapter 4 of Aquinas (the chapter on “Psychology”), I wrote:
As I have emphasized throughout this book, understanding Aquinas requires “thinking outside the box” of the basic metaphysical assumptions (concerning cause, effect, substance, essence, etc.) that contemporary philosophers tend to take for granted. This is nowhere more true than where Aquinas’s philosophy of mind is concerned. Indeed, to speak of Aquinas’s “philosophy of mind” is already misleading. For Aquinas does not approach the issues dealt with in this modern philosophical sub-discipline in terms of their relevance to solving the so-called “mind-body problem.” No such problem existed in Aquinas’s day, and for him the important distinction was in any case not between mind and body, but rather between soul and body. Even that is potentially misleading, however, for Aquinas does not mean by “soul” what contemporary philosophers tend to mean by it, i.e. an immaterial substance of the sort affirmed by Descartes. Furthermore, while contemporary philosophers of mind tend to obsess over the questions of whether and how science can explain consciousness and the “qualia” that define it, Aquinas instead takes what is now called “intentionality” to be the distinctive feature of the mind, and the one that it is in principle impossible to explain in materialistic terms. At the same time, he does not think of intentionality in quite the way contemporary philosophers do. Moreover, while he is not a materialist, he is not a Cartesian dualist either, his view being in some respects a middle position between these options. But neither is this middle position the standard one discussed by contemporary philosophers under the label “property dualism.” And so forth.
To the modern philosophical reader, all this might make Aquinas sound very odd indeed, confusing and perhaps confused… Yet had Aquinas been familiar with the ideas of contemporary philosophers of mind, he would have regarded them as the confused ones, and in particular as having gotten the basic conceptual lay of the land totally wrong. For the “mind-body problem” is essentially an artifact of the early modern philosophers’ decision to abandon a hylemorphic conception of the world for a mechanistic one, and its notorious intractability is, in the view of Thomists, one of the starkest indications of how deeply mistaken that decision was.
End quote. In a recent paper, the esteemed Alfred Freddoso takes his own Thomistic look at contemporary philosophy of mind, and explains how much of what is today taken for granted in the field is “bound to strike a Thomist as strange and insufficiently motivated.” Nor is it only the views of materialists that Freddoso (and I) are critical of. For reasons he clearly explains, the views of many dualists, and even of many orthodox Catholic thinkers, must from a Thomistic point of view be regarded as seriously deficient. Give the paper a read. You’ll find in it, among many other good things, a useful overview of the way the Thomistic approach to issues in the philosophy of mind reflects a broader Aristotelian-Thomistic philosophy of nature.
I have one point of disagreement with Fred, though (as it seems he would agree) it is more terminological than substantive. He says some very kind things about both my book The Last Superstition and David Oderberg’s book Real Essentialism. But he takes exception to Oderberg’s (and my) tendency to characterize Aquinas’s position as “hylemorphic dualism.” Fred writes:
Unlike Feser, I am very uneasy describing St. Thomas’s position as a form of dualism — even ‘hylemorphic dualism’ — since it is precisely the unity of the human being that St. Thomas wants to emphasize over against Plato’s position, which (as he interprets it) posits many substantial forms in the human composite. (The term ‘hylemorphic dualism’ originates, I believe, with David Oderberg in Real Essentialism (New York: Routledge, 2007).) This is largely a verbal disagreement, but I for one resist making Thomistic philosophical anthropology conform to what I believe to be the illegitimate contemporary taxonomy of ‘solutions’ to the alleged ‘mind-body problem’, according to which each solution is either a type of materialism or a type of dualism.
Freddoso is right to say that the term “hylemorphic dualism” probably originates with David Oderberg (certainly it originates with him as far as David or I know), though it is David’s 2005 Social Philosophy and Policy paper “Hylemorphic Dualism” that (at least as far as I know) actually marks its first appearance. But Aquinas’s position is characterized as “Thomistic dualism” in William Hasker’s 1999 book The Emergent Self and J. P. Moreland and Scott Rae’s 2000 book Body and Soul, and Aquinas is characterized as “a non-Cartesian substance dualist” in Eleonore Stump’s 2003 book Aquinas. And there is a good reason why these (and other) writers classify Aquinas as a kind of dualist. The reason is that is that Aquinas just obviously is a dualist given the sense of “dualism” that has long been operative in modern philosophy of mind. As Stump writes:
It is clear that Aquinas rejects the Cartesian or Platonic sort of dualism. On the other hand, Aquinas seems clearly in the dualist camp somewhere since he thinks that there is an immaterial and subsistent constituent of the subject of cognitive function. (p. 212)
In particular, Aquinas holds that the human intellect is immaterial and that because it is, the human soul of which it is a power survives the death of the body. And that is more than enough to make him a dualist as “dualism” is generally understood today. To the vast majority of contemporary philosophers, to say “Aquinas thinks the soul is immaterial and survives the death of the body, but he isn’t a dualist” sounds a little like saying “Aquinas believed the existence of God can be demonstrated, but he isn’t a theist.”
The reason Freddoso (and some other writers on Aquinas) resist the term “dualism” is that they tend to use it in an older sense, to refer more or less exclusively to what is today generally regarded only as one version of dualism among others -- specifically, to what Stump calls “the Cartesian or Platonic sort of dualism.” On a Cartesian or Platonic view, the real you is something entirely immaterial -- your soul -- and the body is merely something with which you are contingently associated, and not essential to you at all. Human beings are violently sundered in two, the seamless unity of their material and immaterial aspects denied. Naturally, Aquinas, who (following both Aristotle and Christian tradition alike) regards our bodily nature as essential to us, rejects such a view. For that reason, Freddoso worries that by applying to Aquinas the “dualism” label:
Thomism gets put into the same general category as philosophical anthropologies according to which human beings are not properly speaking (i.e., per se) animals at all, but instead immaterial souls closely associated with animal bodies… One might have hoped for a more fine-grained problematic to begin with, where Thomistic philosophical anthropology would be seen as (a) clearly distinct from dualism in insisting that human beings are both unified substances and animals in the full-blooded sense and (b) clearly distinct from materialism in insisting that there is a radical metaphysical underpinning, viz., an immaterial form, for the human animal’s distinctiveness from other animals.
The trouble is that the term “dualism” just doesn’t have these exclusively Platonic and Cartesian implications in contemporary philosophy. Many modern dualists are “property dualists,” who hold precisely that human beings are material things and indeed animals of a certain kind, but animals who happen to have immaterial properties in addition to material ones. To be sure (and as the above quote from my Aquinas book indicates) I would not classify Aquinas as a “property dualist” either, in part because it isn’t correct to describe him as holding that thoughts and the like are “properties” of a material substance. But the existence of property dualism as a position within the broad dualist camp nevertheless illustrates the point that “dualism” as it is understood today simply does not imply the idea that a person’s body is not essential to him.
Now Freddoso does have some things to say about property dualism, but his remarks seem to me somewhat odd, and are in my view in any case mistaken. For one thing, he says that though property dualism “is often presented as an alternative to materialism” it is in fact “clearly a form of materialism.” He also writes:
A zombie-world is one which is just like ours in its physical constitution and physical events, but in which there are no sensuous experiences. Is a zombie world possible? If it is, then even so moderate a form of materialism as property dualism is false, since the presence of the sensuous experiences cannot be accounted for merely by the presence of the physical, no matter how the latter is constituted, and sensings and feelings do not necessarily supervene on the physical.
The reason this is odd is that the notion of a “zombie” is commonly put forward precisely in arguments against materialism and in favor of property dualism! For example, David Chalmers’ book The Conscious Mind, which is an especially influential recent defense of the possibility of “zombies,” makes use of the notion precisely as a way of defending property dualism. Since a zombie would be identical to us in all its material properties but devoid of consciousness, it follows (so the argument goes) that consciousness is not material but rather a non-material property of human beings. (In his paper “Why I Am Not a Property Dualist,” John Searle argues that property dualism in fact threatens to collapse into a Cartesian-style substance dualism. While I have criticized other aspects of Searle’s paper, that much seems to me hardly less plausible than Freddoso’s opposite assertion.)
The reason Freddoso says what he does about property dualism seems to be that he associates it with a fairly strong claim about the supervenience of the mental on the physical. But as Chalmers writes:
There is a weaker sort of property dualism with which [Chalmers’] view should not be confused. It is sometimes said that property dualism applies to any domain in which the properties are not themselves properties invoked by physics, or directly reducible to such properties. In this sense, even biological fitness is not a physical property. But this sort of “dualism” is a very weak variety. There is nothing fundamentally ontologically new about properties such as fitness, as they are still logically supervenient on microphysical properties. Property dualism of this variety is entirely compatible with materialism. By contrast, the property dualism that I advocate involves fundamentally new features of the world. Because these properties are not even logically supervenient on microphysical properties, they are nonphysical in a much stronger sense. When I speak of property dualism and nonphysical properties, it is this stronger view and the stronger sense of nonphysicality that I have in mind. (p. 125)
Hence Freddoso is perhaps conflating what is really only one version of property dualism -- what Chalmers calls a “very weak variety” -- with property dualism as such. Be that as it may, there is certainly nothing in property dualism per se that entails materialism. And since property dualism also does not entail treating a person’s body as non-essential to him, there is nothing in dualism per se as the term “dualism” is generally understood today that entails a specifically Platonic or Cartesian conception of persons. That narrow construal of “dualism” has become archaic.
Hence it seems to me that for a Thomist to insist on using “dualism” in the more narrow, archaic sense is like refusing to use the word “atom” the way modern physicists do on the grounds that the ancient atomists thought of atoms as essentially indivisible. In both cases, the meaning of the term has as a matter of linguistic fact simply changed fundamentally and nothing of substance rides on it anyway. Insisting on the older usage gains nothing and has as a downside that it sows confusion. In the case at hand, refusing to allow that Aquinas could in any sense be called a dualist at best seems baffling to most contemporary readers (given that Aquinas affirmed the immateriality of the intellect and the immortality of the soul) and at worst threatens to foster positive misunderstandings (if, for example, it leads any contemporary readers to conclude that Aquinas’s position might be compatible with naturalism broadly conceived).
As my longtime readers know, I have no problem whatsoever with insisting on old ideas and even old usages when something substantive is at stake. Hence I am keen to insist not only on the fundamental importance of the Aristotelian theory of act and potency but even on the language of “act” and “potency,” since I think these terms have connotations which make them more suitable means of conveying the concepts in question than contemporary putative substitutes like “categorical properties” and “dispositional properties.”
But there are other cases where the benefits of reviving older usage are balanced or even outweighed by the costs. For example, if in every context I used the word “science” only in the technical Aristotelian sense of the word, I might please certain Aristotelian or Thomistic readers of the sort who occasionally complain (in the combox, say) that my usage is insufficiently traditional. But I would baffle the vast majority of my readers, who would be led into grave and entirely avoidable misunderstandings, and who are (quite understandably) not keen to read through a primer on the history of philosophical linguistic usage as a prolegomenon to every blog post. And in my estimation, preserving the archaic use of “dualism” is even less important than insisting in every context on the older sense of “science.”