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.

Churchland on dualism, Part I

We have been hammering away at eliminative materialism (EM) in a series of posts. If EM proponents fail to make their own position plausible or even coherent, how do they fare as critics of alternative views? Not much better. Let’s look at Paul Churchland’s treatment of dualism in (the 1988 revised edition of) his textbook Matter and Consciousness. (There’s the book’s cover at left. It’s better than the book itself, which I guess confirms the old adage. I considered using this illustration, but it seemed a bit impolite.)

There are two main problems with Churchland’s discussion. First, his summary of the case for dualism is no good. Second, his arguments against dualism are no good either. In this post we’ll look at the first problem and in a second post I’ll address the second.

What are the main arguments for dualism? Churchland identifies four; he calls them the argument from religion, the argument from introspection, the argument from irreducibility, and the argument from parapsychology. To anyone familiar with the philosophical literature on dualism, this list cannot fail to seem very odd.

One problem with it is that it includes two arguments – the “argument from religion” and the “argument from parapsychology” – that dualist philosophers actually put little or no emphasis on. As Churchland presents the “argument from religion,” it amounts to little more than the claim that “Dualism must be true, because my religion says it is.” He cites no philosophers as actually having given this argument, no doubt because there aren’t any. (Yes, a philosopher who happens to believe on independent grounds that his religion is true and that it entails dualism might present that as an argument for dualism to someone who already agrees with its premises. But no dualist philosopher I can think of has ever pretended that such an argument would be a good stand-alone argument for convincing either an irreligious materialist or even someone whose attitude toward either religion or dualism is noncommittal.)

The “argument from parapsychology” no doubt does have some defenders; certainly there are serious philosophers who have taken the subject of alleged paranormal phenomena seriously either in a sympathetic way (e.g. C. D. Broad and, in recent years, Stephen Braude) or in a critical spirit (e.g. Antony Flew). But this subject does not in fact play much of a role in contemporary debates over dualism, and even those philosophers who believe that at least some purported paranormal phenomena cannot plausibly be explained away in terms of existing scientific theory (e.g. Braude) do not necessarily put such claims forward, primarily or at all, as grounds for accepting dualism.

It is in any event a mistake to think that dualism is intended as a kind of scientific hypothesis put forward as the “best explanation” of the empirical evidence, parapsychological or otherwise. The central arguments for dualism have always been attempts at metaphysical demonstration, intended to show conclusively that whatever the mind is, it cannot even in principle be material. And this brings us to the most glaring fault with Churchland’s list: He simply ignores these key arguments entirely. For example, though he purports to summarize Descartes’ own reasons for endorsing dualism, and rightly notes that Descartes thought that certain key mental phenomena are irreducible to material phenomena, he fails even to mention the two arguments Descartes put the most emphasis on: the clear and distinct ideas argument (these days often called the conceivability argument or the modal argument), and the indivisibility argument (which is related to what is often called the unity of consciousness argument). The first argument (which I have discussed in a previous post) holds that since – the argument claims – it is metaphysically possible for mind to exist apart from anything material, it cannot be material. The second holds that the mind has a kind of unity or indivisibility-in-principle that nothing material can have. (Variations on this basic idea were also defended by the likes of Leibniz and Kant.)

It isn’t like these arguments are not well known. Nor are they mere historical relics; they have defenders to this day. (For those who are interested, I discuss them in detail in my book Philosophy of Mind.) The modal argument in particular received renewed attention in the wake of Kripke’s Naming and Necessity, and thus in the years leading up to the publication of Churchland’s book. It was defended by Richard Swinburne in The Evolution of the Soul, which appeared in 1986 – two years before Churchland’s revised edition – and by W. D. Hart in The Engines of the Soul, which itself came out in 1988. (Charles Taliaferro is another philosopher who has defended it in the years since, in his book Consciousness and the Mind of God.)

Churchland also ignores – as, in fairness, almost all contemporary philosophers of mind do – what early modern writers like Malebranche regarded as the central proof of dualism, viz. that dualism follows from the very mechanistic conception of matter Cartesians and materialists hold in common. For if color, odor, taste, sound, etc., as common sense understands them, do not exist in matter itself but only in our perceptual experience of matter, then those experiences cannot be material. (I have discussed this argument in previous posts as well, e.g. here and here.)

What is in fact the chief argument for dualism, at least from the point of view of the classical (Platonic-Aristotelian-Thomistic-Scholastic) traditions in philosophy, concerns, not sensory qualities or “qualia,” but rather our capacity for abstract thought. For concepts, and our thoughts about them, are universal in a way nothing material can be, and (sometimes, anyway) determinate, precise, or unambiguous in a way nothing material can be. (I have discussed this sort of argument too in many earlier posts, e.g. here and here.) While this line of argument has also been largely ignored by contemporary academic philosophers of mind, it was defended by Mortimer Adler in the years leading up to the publication of Churchland’s book, and by 20th century Thomist writers generally. Needless to say, Churchland ignores it as well.

So, while Churchland pretends to be summing up “some of the main considerations” usually given in support of dualism, he completely ignores the arguments the most prominent dualist philosophers actually regarded as the most important, and includes arguments that dualists do not typically make use of – arguments that are either clearly feeble (the “argument from religion,” as Churchland presents it) or which rest on premises which are as controversial as dualism itself is (the “argument from parapsychology”). The rhetorical effect is obvious: The unwary reader, who assumes that a textbook will give him an accurate summary of what each side has to say, is bound to come away with a completely distorted conception of the case for dualism. In particular, he is bound to think it far weaker than it actually is.

I am not claiming that Churchland is knowingly perpetrating what looks like a pretty sleazy rhetorical tactic. I think he is, like most materialists, simply ignorant of what most dualists have actually said. He no doubt thinks he knows enough about what they say to be justified in concluding that their position is not worth looking into any further than he already has. He is wrong, but will never know that he is, because he has gotten himself onto the sort of merry-go-round that (as we have seen in recent posts) naturalists seem to have so much difficulty keeping off of: “I know that dualism is too silly to investigate any further because of how bad the arguments for it are; and I know that I must be understanding those arguments correctly because dualism is obviously just too silly to be worth investigating any further.”

The thing is, books like Matter and Consciousness contribute to the formation of the same mindset in others. As generation after generation of philosophy students are taught out of such books, the conclusion that dualism is intellectually disreputable comes to seem something that “everyone knows.” In fact, what “everyone knows” is nothing more than a bunch of straw men and circular arguments, bounced around the materialist echo chamber long enough that no one can hear anything else. (This is, of course, exactly parallel to what most atheist philosophers “know” about the classical arguments for God’s existence, as I have noted here, here, and here. The hegemony of atheism and materialism crucially depend on a stubborn and studied ignorance of what theists and dualists have actually said.)

Having said all that, Churchland is at least correct to say that what he calls the "argument from introspection" and the "argument from irreducibility" are prominent arguments for dualism. Unfortunately, what he says about these arguments is no good either. We’ll see why in part II.

Mind-body problem roundup

For readers who might be interested, I thought it would be useful to gather together in one place links to various posts on the mind-body problem and other issues in the philosophy of mind.  Like much of what you’ll find on this blog, these posts develop and apply ideas and arguments stated more fully in my various books and articles.  Naturally, I address various issues in the philosophy of mind at length in my book Philosophy of Mind, of which you can find a detailed table of contents here.  (The cover illustration by Andrzej Klimowski you see to the left is from the first edition.)  You will find my most recent and detailed exposition of the Aristotelian-Thomistic (A-T) approach to issues in the philosophy of mind in chapter 4 of Aquinas.  There is a lot of material on the mind-body problem to be found in The Last Superstition, especially in various sections of the last three chapters.  And there is also relevant material to be found in Locke, in the chapter I contributed to my edited volume The Cambridge Companion to Hayek, and in various academic articles.

Churchland on dualism, Part V

Paul Churchland has just published a third edition of Matter and Consciousness, his widely used introductory textbook on the philosophy of mind.  The blog Philosophy of Brains has posted a symposium on the book, with contributions from Amy Kind, William Ramsey, and Pete Mandik.  Prof. Kind, who deals with Churchland’s discussion of dualism, is kind to him indeed -- a little too kind, as it happens.  Longtime readers will recall a series of posts I did several years ago on the previous edition of Churchland’s book, in which I showed how extremely superficial, misleading, and frankly incompetent is its treatment of dualism.  Prof. Kind commends Churchland’s “clear writing style and incisive argumentation” as “a model for us all.”  While I agree with her about the clarity of Churchland’s style, I cannot concur with her judgment of the quality of the book’s argumentation, for at least with respect to dualism, this new edition is as bad as the old. 

Two, four, six, eight! Who do you reincarnate?

Could there be such a thing as reincarnation?  A necessary condition would be the truth of some form of dualism.  So far so good, since (I would say) some form of dualism is true.  But which form?  There are at least three to choose from: substance dualism, the version associated with Plato and Descartes; property dualism, associated with the likes of John Locke, David Chalmers, and (the early) Frank Jackson; and the hylemorphic dualism defended within the Aristotelian-Thomistic metaphysical tradition.  Are all of these equally favorable to a defense of reincarnation?

Oderberg on hylemorphic dualism

The arguments presented in my recent series of posts on dualism have been more or less ecumenical. That is to say, they have not attempted to defend any particular form of dualism, but merely tried to show that the mind must be immaterial, leaving open the question of how exactly the immaterial mind relates to the material side of human nature.

But as readers of The Last Superstition and Philosophy of Mind know, I do not in fact think that all forms of dualism are equally defensible. The version I would myself defend is neither Cartesian substance dualism, nor property dualism, nor emergent dualism, but rather hylemorphic dualism, so called because it is informed by hylemorphism, the Aristotelian-Thomistic-Scholastic view that material substances are composites of form and matter. (The theory is also sometimes called Thomistic dualism, after Thomas Aquinas, its most significant advocate historically.)

David S. Oderberg (who seems to have invented the label "hylemorphic dualism") is among the view's most skilled contemporary defenders. His 2005 article "Hylemorphic dualism" is must reading for those interested in the subject, and he has recently published another important article entitled "Concepts, dualism, and the human intellect," which is available here. Check it out.

Incidentally, anyone who wants to see what a rigorous and detailed contemporary defense of Aristotelian-Thomistic metaphysics would look like should invest in Oderberg's brilliant recent book Real Essentialism.

Churchland on dualism, Part III

To conclude our look at Paul Churchland’s critical discussion of dualism in his textbook Matter and Consciousness, let’s consider the arguments he presents against dualism. There are four of them, and they can be summarized as follows:

1. The argument from Ockham’s razor: Postulating two basic kinds of substance, material and immaterial, needlessly complicates our ontology if mental phenomena can be adequately explained in terms of material substance alone. That they can be so explained is indicated by the next two arguments:

2. The argument from the explanatory impotence of dualism: Materialist explanations can appeal to the many details of the brain’s structure and function revealed by modern neuroscience, while dualists have yet to provide a comparable account of the structure and function of immaterial substance.

3. The argument from the neural dependence of all known mental phenomena: As both everyday experience and neuroscientific research show, reasoning, emotion, and consciousness are all very closely correlated with various processes in the brain, which is not what we would expect if these mental phenomena were associated with an immaterial substance.

4. The argument from evolutionary history: The evolutionary process that gave rise to the human species proceeded via purely material mechanisms from a purely material starting point, so that the end result must itself be purely material.

Churchland acknowledges that none of these arguments is by itself absolutely conclusive. But he does think the third one “comes close to being an outright refutation of (substance) dualism,” and he clearly believes that in tandem the arguments consign dualism to the dustbin for all practical purposes. No doubt most materialists would agree with him. But in fact these arguments have, I maintain, no force at all against dualism. None. Dualism may or may not in fact be true – obviously I think it is true, but that is another issue. The point is that, even if it were false, these arguments have no tendency to show that it is.

How can I say that? Easy. Keep in mind first of all that, as I have emphasized in the earlier posts in this series, the chief proponents of dualism historically have not defended their position as an “explanatory hypothesis” put forward as the “best explanation” of the “empirical data.” That just isn’t what they are up to, any more than geometers or logicians are. They are attempting instead to provide a strict demonstration of the immateriality of the mind, to show that it is metaphysically and conceptually impossible for the mind to be something material. Their attempts may or may not succeed – again, that is another question. But that is what they are trying to do, and thus it simply misses the point to evaluate their arguments the way one might evaluate an empirical hypothesis. When Andrew Wiles first claimed – correctly, as it turned out – to have proven Fermat’s Last Theorem, it would have been ridiculous to evaluate his purported proof by asking whether it best accounts for the empirical evidence, or is the “best explanation” among all the alternatives, or comports with Ockham’s razor. Anyone who asked such questions would simply be making a category mistake, and showing himself to be uninformed about the nature of mathematical reasoning. It is equally ridiculous, equally uninformed, equally a category mistake, to respond to Plato’s affinity argument, or Aristotle’s and Aquinas’s argument from the nature of knowledge, or Descartes’ clear and distinct perception argument, or the Cartesian-Leibnizian-Kantian unity of consciousness argument, or Swinburne’s or Hart’s modal arguments, or James Ross’s argument from the indeterminacy of the physical, by asking such questions. As with a purported mathematical demonstration, one can reasonably attempt to show that one or more of the premises of such metaphysical arguments are false, or that the conclusion does not follow. But doing so will not involve the sorts of considerations one might bring to bear on the evaluation of a hypothesis in chemistry or biology.

Of course, Churchland, committed as he is to a Quinean form of scientism, thinks that all good theories must in some sense be empirical scientific theories. He rejects the traditional conception of metaphysics as a rational field of study distinct from and more fundamental than physics, chemistry, biology, and the like, and would deny that there is any such thing as sound metaphysical reasoning that is not in some way a mere extension of empirical hypothesis formation. But he cannot simply assume all of this in the present context without begging the question, because this sort of scientism is precisely (part of) what the dualist denies. (As we have seen in earlier posts on naturalism, this kind of circular reasoning is absolutely rife in naturalist thinking.)

It is obvious, then, why Churchland’s first two arguments have no force, for they simply misconstrue the nature of the case for dualism. If any of the dualist arguments just mentioned works, then the immateriality of the mind will have been demonstrated, and asking “But do we really need to postulate immaterial substance?” or “How much can we really know about such substances?” would not be to the point. For we would not in that case be hypothetically “postulating” anything in the first place, but directly establishing its existence; and its existence will have been no less established even if we could not say much about its nature.

But this brings us to an additional problem with Churchland’s second argument, which further underlines just how embarrassingly uninformed he is about what dualists have actually said. In developing his “explanatory impotence” objection, Churchland complains that dualists have told us very little about the nature of “spiritual matter” or the “internal constitution of mind-stuff,” about the “nonmaterial elements that make it up” and the “laws that govern their behavior.” This is, for anyone familiar with the thought of a Plato, an Aquinas, a Descartes, or a Leibniz, simply cringe-making. The soul is not taken by these writers to be “made up” out of anything, precisely because it is metaphysically simple or non-composite. It is not a kind of “stuff,” it is not made out of “spiritual matter” (whatever that is), and it is not “constituted” out of “elements” which are related by “laws.” Nor is this some incidental or little-known aspect of their position – it is absolutely central to the traditional philosophical understanding of the soul. As is so often the case with naturalistic criticisms of dualism, theism, etc., Churchland’s argument is directed at a breathtakingly crude straw man.

This appalling ignorance of the actual views of dualists manifests itself again in Churchland’s third argument. Churchland himself admits that this argument has no effect against property dualism, since property dualism itself takes the brain to be the seat of mental phenomena. But he fails to see that it has no effect against the other main varieties of dualism either, given what they actually say about the relationship between the mind and the brain.

For starters, let’s take Aristotelian-Thomistic (A-T) hylemorphic dualism. The A-T view is that the intellect is immaterial, but that sensation and imagination are not. Hence it is no surprise at all that neuroscience has discovered various neural correlates of mental imagery and the varieties of perceptual experience. Moreover, A-T holds that though intellect is immaterial, its operation requires the presence of the images or “phantasms” of the imagination. Hence it is no surprise that neural damage can affect even the functioning of the intellect. Most importantly, the soul, of which intellect, sensation, and imagination are all powers, is not a complete substance in its own right in the first place, but rather the form of the body. The way intellectual and volitional activity relates to a particular human action is, accordingly, not to be understood on the model of billiard ball causation, but rather as the formal-cum-final causal side of a single event of which the relevant physiological processes are the material-cum-efficient causal side. That alterations to the body have mental consequences is thus no more surprising than the fact that altering the chalk marks that make up a triangle drawn on a chalkboard affects how well the marks instantiate the form of triangularity. It is important to emphasize that none of this involves any sort of retreat from some stronger form of dualism, as a way of accommodating the discoveries of contemporary neuroscience; it is what A-T has always said about the relationship between soul and body. There is absolutely nothing in modern neuroscience that need trouble the A-T hylemorphic dualist in the slightest.

What about the Cartesian dualist? Don’t the differences between Descartes’ views and those of his Scholastic predecessors make him vulnerable to the findings of neuroscience in a way the latter are not? No, they don’t. For one thing, and as I have noted in an earlier post, Descartes’ views on this subject were not in fact quite as different from those of his predecessors as is often supposed. For example, Descartes’ view appears to have been that it is the intellect, specifically, which is to be identified with the ego he thinks is capable of existing apart from the body. Sensations, emotions, and the like he regarded, not as purely mental phenomena, but rather as hybrid properties which can be predicated only of the soul-body composite, and not the soul alone. Hence even on Descartes’ view it is not at all surprising that neuroscience has discovered all sorts of correlations between various aspects of perceptual experience and various emotional states on the one hand, and various processes in the brain on the other.

Now what is true is that the Cartesian has a difficulty explaining mind-body interaction that the A-T view does not have, as I have discussed here and here. And the reason is that Descartes rejected the notion that the soul is the formal cause of the body. That is an enormously consequential difference between the two views. But it has nothing to do with the specific question about whether a dualist need be troubled by the discovery of detailed correlations between mental phenomena and neural phenomena, which is what is at issue in the argument of Churchland’s under consideration. In particular, even the Cartesian need not be troubled by the fact that intellectual activity too (and not just sensation, emotion, and the like) can be dramatically affected by changes to the brain.

Why not? For one thing, as Churchland himself admits, the Cartesian regards the brain as a “mediator” between the soul and the rest of the body, so that we should expect that damage to this mediator will prevent the intellect from receiving the information it derives from the body and from controlling bodily behavior as well as it normally would.

But there is a deeper consideration. Consider the following analogy: A typed, written, or spoken token of the word “bark,” considered merely as a material object, has all sorts of complex physical properties, and those physical properties are highly relevant to its status as a word, as a bearer of linguistic meaning. Alter the physical properties of the token too radically, and it can no longer convey the meaning it once did. For example, if the ink should smear, the sound be muffled, or the power source to a word processor be cut off, the word will disappear, or might at least become so distorted that it becomes unintelligible. It would be absurd, though, for someone to suggest that these facts lend any support whatsoever to the claim that a word token qua word token is exhausted by its physical properties. It clearly is not. It is, for example, indeterminate from the physical properties alone whether the “bark” in question is the bark of a dog or the bark of a tree. Indeed, since the fact that the relevant sounds and shapes are associated with a certain meaning is entirely contingent, an accident of the history of the English language, it is indeterminate from the physical properties alone whether the word has any meaning at all. In short, the physical properties are a necessary condition for any particular physical object’s counting as a word token, but they are not a sufficient condition. And piling up bits of physicochemical knowledge about word tokens cannot possibly change this fact in the slightest, for it is a conceptual point about the nature of words, not an empirical point about what the latest research in phonetics (or whatever) has turned up.

In the same way, the dualist claims to be making a conceptual point about the relationship between mind and body, one to which neuroscientific research, important and interesting as it is in itself, is irrelevant. The existence of such-and-such physiological phenomena may well be a necessary condition for the existence of intentional human actions, intelligible speech, and so forth, but it is not and cannot be a sufficient condition. And that remains true whether we are interpreting dualism in A-T terms or in Cartesian terms. A-T regards the soul as the formal cause of a single substance of which the matter of the body is the material cause. Cartesians regard mind and matter as two distinct substances. Either way, there is not, and in principle cannot be, anything distinctively mental in matter as such, any more than a word token, considered merely as an arrangement of ink marks or a pattern of sound waves, has any meaning on its own. Or at least, there cannot be if dualism is correct. No amount of neuroscientific evidence can undermine this judgment, because what is at issue is whether any purely material phenomena at all, neurological or otherwise, can in principle be mental.

“But doesn’t that make dualism unfalsifiable?” If “unfalsifiable” means “not subject to rational evaluation and criticism,” then no, of course it isn’t unfalsifiable. Metaphysical arguments, like mathematical arguments, are perfectly susceptible of rational analysis and refutation, even if, like mathematical arguments, such analysis does not involve the weighing of probabilities, the comparison of alternative empirical hypotheses, etc. If “unfalsifiable” means instead “not subject to refutation via empirical scientific research,” then yes, dualism is unfalsifiable in that sense. But so is mathematics, and yet that doesn’t detract from its status as a rational field of investigation. Again, if the materialist wants to insist that all rational inquiry must ultimately be a kind of empirical scientific inquiry, he is welcome to make the case, but he cannot simply assume the truth of scientism when criticizing the dualist, otherwise he will simply be begging the question.

And that brings us, finally, to the fourth of Churchland’s arguments, the argument from evolution. Here again we have an argument that is entirely without force, and the main reason should be obvious from what has just been said: Dualism is a metaphysical theory, not an empirical hypothesis, and thus it is not the sort of thing that could be refuted by empirical biological findings any more than by neuroscientific ones.

But there is more to be said. Churchland’s fourth argument is also question-begging. For whether Darwinian evolution – which is supposed to be a purely materialist theory – is in fact a complete explanation of human nature depends on whether human nature is entirely material. And of course, the dualist’s claim is precisely that human beings are not and cannot be purely material, in which case no purely materialist theory could possibly provide a complete explanation of human nature. Hence it is no good to merely to assert, as an argument against dualism, that Darwinism has already explained human nature in materialist terms. That simply assumes the falsity of dualism without proving it.

Nor is it any good to stamp one’s feet and insist that if Darwinism entails materialism, then we had all better be materialists. Because here’s a newsflash: If Darwinism entailed that 2 + 2 = 5, what that would show is, not that 2 + 2 = 5, but that Darwinism is false, or at least needs to be seriously modified. Similarly, if Darwinism really does entail materialism, but the arguments of an Aquinas, a Descartes, or a James Ross show that materialism is false, then so much the worse for Darwinism. It had better adapt itself to the metaphysical facts, or be selected out. Like so many other naturalists, Churchland waves the “evolution” talisman as if it sufficed to shut off all debate, assuring us that in light of Darwinism we “are creatures of matter” and “should learn to live with that fact.” But this is sheer, question-begging bluff, not serious philosophical argument.

We have seen, then, over the course of these three posts, that Churchland’s treatment of dualism in Matter and Consciousness, though purporting to be a balanced summary, is in fact almost completely worthless both as a guide to what dualists have actually said and as a critique of dualism. And this is a textbook! And a widely used one, which has long been in print – it was one of the books I was taught out of as an undergraduate, and (I am ashamed to say) as a teacher I once used it myself. It took me many years to see just how bad it is. Most students who have read it probably have no idea, and never will.

But that’s how bad ideas spread: By ignorance and intellectual dishonesty smugly masquerading as expertise. Here, as with the debate over theism, the naturalistic skeptic can maintain the illusion of rational superiority only to the extent that he and his readers remain ignorant of what the great thinkers of the past have actually said. For to paraphrase Cardinal Newman, to be deep in history is to cease to be a naturalist.

Vallicella on hylemorphic dualism, Part II

Bill Vallicella has kindly replied to my response to his recent post on hylemorphic dualism.  The reader will recall that Bill had suggested in his original post that, given the apparent tension between hylemorphism and dualism, Aquinas’s hylemorphic dualism seems ad hoc and motivated by Christian theological concerns rather than by philosophical considerations.  I argued that this charge cannot be sustained.  Whether or not one ultimately accepts hylemorphic dualism, if one agrees that there are serious arguments both for hylemorphism and for dualism, then -- especially when we add independent metaphysical considerations such as the Scholastic principle that the way a thing acts reflects the manner in which it exists -- one should at least acknowledge that hylemorphic dualism has a philosophical rationale independent of any Christian theological concerns.  It seems Bill still disagrees, but I do not see how his latest post gives any support to his original charge.

Searle, Aquinas, and property dualism

In an addendum to his article “Why I Am Not a Property Dualist,” John Searle suggests that property dualism really entails substance dualism. For it describes mental properties as “arising from” and existing “over and above” the brain, and “these metaphors suggest that… consciousness is something separate from the brain” given that “uncontroversial properties of the brain, like weight, shape, colour, solidity, etc.” are not said to exist in that way. For consciousness to exist “over and above” the brain requires that it be “a separate thing, object, or non-property type of entity.”

Searle’s claim here seems reminiscent in some ways of Aquinas’s argument for the subsistence of the human soul at Summa Theologiae I.75.2:

Therefore the intellectual principle which we call the mind or the intellect has an operation "per se" apart from the body. Now only that which subsists can have an operation "per se." For nothing can operate but what is actual: for which reason we do not say that heat imparts heat, but that what is hot gives heat. We must conclude, therefore, that the human soul, which is called the intellect or the mind, is something incorporeal and subsistent.

Aquinas has argued earlier for the first claim made in this passage, viz. that intellectual operations do not involve a bodily organ. What he saying here is that this claim entails that that which carries out these operations, the human soul, must “subsist” apart from the body; it isn’t a mere accident or attribute of the body. The reason is the Scholastic principle that agere sequitur esse, activity follows upon being. Heat, as a mere accident or attribute, cannot cause something to be hot; rather it is the substance which has the heat that causes something else to be hot. Similarly, an operation which is not carried out by any bodily organ but which – qua operation rather than substance – cannot exist apart from some substance or other, must inhere in something immaterial.

So, when Searle tells us that immaterial mental properties would have to inhere in something immaterial rather than in a material object like the brain, he is saying something which seems to dovetail with Aquinas’s argument.

Still, things are a bit more complicated than that. For one thing, unlike many contemporary property dualists, Aquinas does not regard consciousness (as contemporary philosophers tend to understand “consciousness”) as immaterial. Rather, it is intellectual activity (grasping abstract concepts, reasoning, etc.) that he takes to be immaterial. Second, Aquinas is not only not a property dualist, he is not (contrary to appearances) a substance dualist either, certainly not in the way that sort of view has been understood since Descartes. Rather, he is a hylemorphic dualist. From a Thomistic point of view, substance dualism, property dualism, materialism, idealism, neutral monism, and all other post-Cartesian theories of the mind presuppose a mistaken and muddleheaded conception of both mind and matter – a conception which (among other things) makes it very difficult for contemporary philosophers even to understand the Thomistic view. As when dealing with Aquinas’s position on other specific philosophical questions, the only way properly to understand what he says about the relationship between mind and body is to situate it within his general metaphysics, which presupposes an understanding of the notions of act and potency, form and matter, substance and accident, essence and existence, analogical predication, etc. I set all this out in Aquinas, with chapter 4 devoted to Aquinas’s psychology and how it differs radically from contemporary substance dualism, property dualism, etc.

Now, some further reading, while you wait for your copy of Aquinas to arrive: First, my essay “Why Searle Is a Property Dualist,” which explains why Searle’s own anti-materialist arguments in philosophy of mind do in fact entail property dualism, despite his attempt to avoid this result. Second, check out David Oderberg’s article “Hylemorphic Dualism” for an overview of the Thomistic position. Third, take a look at Alfred Freddoso’s article “Good News, Your Soul Hasn’t Died Quite Yet” for a discussion of some of the differences between the Thomistic view and the standard modern ones (and why Catholics, especially, should be wary of the latter, including modern versions of dualism).

Searle and property dualism

David Lewis once wrote that “philosophical theories are never refuted conclusively. (Or hardly ever, Gödel and Gettier may have done it.)” To this list should be added John R. Searle, who has in my estimation conclusively refuted the computationalist theory of mind – not so much with his famous “Chinese Room” argument, but with the less well-known but far more devastating arguments presented in his paper “Is the brain a digital computer?” and in chapter 9 of his brilliant book The Rediscovery of the Mind. When (not if, but when) the philosophers and psychologists of the future look back at the bizarre fad for characterizing the brain as a kind of computer and the mind as software, and ask “So what the hell was that all about?”, Searle will be remembered as the man who did more than any other philosopher to break the spell of this illusion.

Searle is also an effective critic of other materialist theories of the mind. But though he rejects all extant forms of materialism, Searle also famously denies being any kind of dualist. Still, his critics regularly insist that his views nevertheless entail dualism whether he realizes it or not, and that this suffices to show that they are mistaken. In short, Searle says: “My arguments are correct, and they do not entail dualism,” while his critics say: “Searle’s arguments do entail dualism, and therefore they are incorrect.” In my view both sides are partly right and partly wrong: Searle’s arguments are correct, and they do entail dualism.

As my longtime readers know, the version of dualism I think one ought to accept is Aristotelian-Thomistic hylemorphic dualism. As it happens, Searle’s views have been compared by some commentators to Aristotle’s (see e.g. Alan Code’s essay in Lepore and van Gulick’s John Searle and his Critics). But Searle rejects any such interpretation. (At a conference at which Searle and I were both presenters, I gave a paper the first part of which put forward a diagnosis and critique of naturalistic theories of the mind, and the second part of which proposed a return to hylemorphism as a remedy. Searle called the first part “brilliant” and the second part “crazy.” Coming from a man whose work I admire so much, that was good enough for me. The first part, incidentally, would go on to become “Hayek the cognitive scientist and philosopher of mind,” in The Cambridge Companion to Hayek. The second part was merely a sketch of ideas that I have developed in more detail elsewhere, most fully in The Last Superstition and in the forthcoming Aquinas.)

Indeed, when Searle has worked his positive views out more fully, the version of dualism they end up resembling most is property dualism. But Searle rejects this interpretation as well, arguing against it at length in his article “Why I am not a property dualist.” Victor Reppert kindly linked yesterday to a paper of mine, “Why Searle is a property dualist,” which replies to this article of Searle’s. Since Searle’s essay has just been reprinted in his new anthology Philosophy in a New Century, I thought I would post a link of my own to my reply, for what it is worth.

(Bonus link: Here is an interview Steven Postrel and I did with Searle for Reason magazine some years back. Among other things, it gives a good sense of Searle’s political views, which aren’t quite the sort you’d expect from a UC Berkeley professor.)

Against “neurobabble”

Every written token of the English word “soup” is made up of marks which look at least vaguely like “s,” “o,” “u,” and “p.”  Of course, it doesn’t follow that the word “soup” is identical to any collection of such marks, or that its properties supervene on the material properties of such marks, or that it can be explained entirely in terms of the material properties of such marks.  Everyone who considers the matter knows this.

To borrow an example from psychologist Jerome Kagan, “as a viewer slowly approaches Claude Monet's painting of the Seine at dawn there comes a moment when the scene dissolves into tiny patches of color.”  But it doesn’t follow that its status and qualities as a painting reduce to, supervene upon, or can be explained entirely in terms of the material properties of the color patches.  Everyone who considers the matter knows this too.

Somehow, though, when neuroscientists discover some neural correlate of this or that mental event or process, a certain kind of materialist concludes that the mind’s identity with, or supervenience upon, or reducibility to, or complete explanation in terms of neural processes is all but a done deal, and that the reservations of non-materialists are just so much intellectually dishonest bad faith.  In a recent online op-ed piece for The New York Times, and in an apt phrase, philosopher of mind Tyler Burge criticizes this tendency as “neurobabble,” which produces only “the illusion of understanding.”  For it is as fallacious as any parallel argument about words or paintings would be.

Churchland on dualism, Part II

Let’s continue our look at Paul Churchland’s critical discussion of dualism in his textbook Matter and Consciousness. I have noted that while Churchland neglects even to mention the most important arguments for dualism and devotes space to arguments that dualist philosophers themselves don’t actually put much stock in, he does at least discuss two arguments that many such philosophers do think important: the argument from introspection and the argument from irreducibility.

As Churchland summarizes the argument from introspection, it states that the thoughts, sensations, desires, and emotions we encounter in introspection are just plainly different from electrochemical activity in neural networks. As he summarizes the argument from irreducibility, it states that language, reasoning, the introspectible qualities of sensations, and the meaningful contents of our thoughts cannot plausibly be accounted for in materialist terms; for example, knowledge of the molecular structure of a rose and/or of the brain would not allow a physicist or chemist to predict what it would be like to experience the smell of a rose.

Churchland’s summary of these arguments is superficial. For example, it is clear from his gloss on the argument from irreducibility that he regards Frank Jackson’s famous “knowledge argument” as an important instance of it. Yet he does not actually state Jackson’s argument, thus denying the unwary reader an opportunity to appreciate its full power. (Churchland does briefly discuss Jackson’s argument later in the book, but only after having disposed of dualism and plumped for materialism, thus giving the misleading impression that the argument is merely a puzzle an already-established materialism must solve rather than an independent argument for dualism in its own right.)

Worse than this, though, are the responses he gives to the two arguments in question, which are presented as decisive but are in fact exceedingly feeble. The argument from introspection has no force, Churchland assures us, because introspection cannot be trusted in light of the fact that there are clear cases from the history of science showing that our natural powers of observation have misled us in other domains. What cases are these? “The red surface of an apple does not look like a matrix of molecules reflecting photons at certain critical wavelengths, but that is what it is,” Churchland says; “The sound of a flute does not sound like a sinusoidal compression wave train in the atmosphere, but that is what it is. [etc.]”

The problem with this response should be obvious, at least to someone with knowledge of the history of the mind-body problem and of modern philosophy generally. In particular, there is an obvious reason why the cases Churchland appeals to not only do not make the point he thinks they do, but in fact make the case for dualism even stronger. For the reason the identities in question – red with such-and-such a light wavelength, sound with a such-and-such a wave pattern, etc. – are plausible in the first place is that the early modern thinkers who inaugurated the “mechanical” conception of nature that informs modern science introduced a crucial distinction between features of the observable world that are observer-relative and those that are observer-independent – the famous primary quality/secondary quality distinction (spelled out in different ways by Galileo, Descartes, Locke, et al.). Colors, sounds, heat, cold, and the like as common sense understands them were relegated to the “observer-relative” side of the divide, and color, sound, heat, cold, etc. as objective, physical properties were, accordingly, redefined in terms of wave activity, the motions of particles, or some other “observer-independent” phenomena.

To see how this works in the case of one of Churchland’s examples, let’s distinguish between RED (in caps) and red (in italics) as follows:

RED: the qualitative character of the color sensations had by a normal observer when he looks at fire engines, “Stop” signs, Superman’s cape, etc. (which is different from the qualitative character of the sensations had by e.g. a color blind observer)

red: whatever physical property it is in fire engines, “Stop” signs, Superman’s cape, etc. that causes normal observers to have RED sensations

Now what seems to common sense to be very different from “a matrix of molecules reflecting photons at certain critical wavelengths” is RED. And sure enough, what science has shown to be identical to “a matrix of molecules reflecting photons at certain critical wavelengths” is only red, not RED. Indeed, part of the reason for distinguishing red and RED is precisely that RED seems clearly not to be identical to something like “a matrix of molecules reflecting photons at certain critical wavelengths,” since the “matrices of molecules” etc. are what they are regardless of who is looking at them while qualitative character is observer-relative.

Part of the problem with Churchland’s response to the argument from introspection, then, is that it commits a fallacy of equivocation: The sense of “red” in which “Red seems different from any property of a matrix of molecules etc.” (i.e. RED) is different from the sense of “red” in which “Science has shown that red really is just a property of a matrix of molecules etc.” (i.e. red). A similar fallacy is committed when he appeals instead to sounds or any other sensory qualities. Thus his examples do not show that our powers of observation have misled us in other domains, and thus should not be trusted in the case of introspection.

That’s one problem with his response. Another is that when we understand what is really going on in the history-of-science examples Churchland appeals to, we can see that they actually strengthen the case for dualism rather than undermine it. For if colors, sounds, heat, cold, etc. as common sense understands them – that is, in terms of their qualitative, phenomenal character – exist only in the mind of the observer and not in the physical world (which is comprised of nothing more than colorless, odorless, soundless, tasteless particles in motion, or whatever), then it seems clear that they cannot exist in the brain, or in any other physical object or system of physical objects, either. Hence they must be immaterial. As I have noted before, that was exactly the conclusion explicitly drawn by early modern thinkers like Cudworth and Malebranche – and at least implicitly by Descartes, Locke, and the other early modern advocates of the “mechanical philosophy” who also happened to be dualists – and by several philosophers since. Their view was that dualism, far from being a pre-scientific holdover destined to be abandon once we have sufficient knowledge of the brain, in fact follows from the very mechanistic conception of matter taken for granted in modern science. The basic problem was one of the themes of Thomas Nagel’s celebrated 1974 article “What is it like to be a bat?” (though Nagel is less committal there about precisely what philosophical conclusion we ought to draw from the problem). It was explicitly appealed to in defense of dualism in Richard Swinburne’s 1986 book The Evolution of the Soul.

Now Churchland or some other materialist might think there is a way to carve up the conceptual territory that doesn’t have such an implication. Fine and dandy, let’s hear it and evaluate it. But he oughtn’t to pretend that the “reductions” in question clearly favor materialism when in fact, historically, they were taken to favor the opposite view! And, especially, he oughtn’t to convey this false impression when purporting to offer an evenhanded presentation of the case for dualism.

Churchland’s treatment of the argument from irreducibility is equally bad. As evidence that our powers of reasoning can in fact be accounted for in materialistic terms, he appeals to the existence of electronic calculators. As evidence that language can be similarly accounted for, he appeals to the existence of “computer languages.” He fails even to mention the most glaringly obvious reply to such “explanations” – that they involve nothing more than a couple of bad puns, since so-called calculators don’t literally “calculate” and computers don’t literally possess “language.” Rather, both electronic calculators and computers generally are inherently devoid of any intentionality or powers of reasoning whatsoever, and have simply been designed by human beings – who do have genuine powers of reasoning and language – to carry out certain operations that aid us in our exercises in calculation and the like by simulating certain mental processes. To “explain” mental phenomena in terms of what computers do is thus precisely to get things back-asswards, since what computers do cannot be accounted for apart from the human minds which assign to their states and operations whatever meanings they have.

Again, the point isn’t that Churchland might not have a way to respond to such arguments. The point is that he pretends that the claims he makes easily and uncontroversially rebut the argument from irreducibility when in fact his claims are extremely controversial even among non-dualists. (John Searle and Hubert Dreyfus are only the two most prominent non-dualist philosophers to have criticized the suggestion that mental processes can be explained in terms of “computational” ones.) The hapless beginning student coming away from Churchland’s discussion would have no idea that his “Gee whiz, look what computers can do!” shtick is, by itself anyway, philosophically about as serious as “proving” that time travel is theoretically possible based only on what one saw once in a Star Trek episode.

Churchland also suggests that whatever explanatory difficulties materialism has are at least equally matched by any dualist attempt to explain mental phenomena in terms of “nonphysical mind-stuff.” Here again Churchland proves only that he doesn’t understand what the main arguments for dualism actually say. As I noted in my first post in this series, those arguments are not quasi-scientific “explanatory hypotheses” in the first place, but rather attempts at metaphysical demonstration. They do not “postulate” “mind-stuff” (whatever that is) any more than mathematicians “postulate” the existence of the number 48 as the “best explanation” of why 47 and 49 do not fall right next to each other in the series of natural numbers. If the arguments fail, they do not fail for the sorts of reasons that explanatory hypotheses fail (considerations of parsimony, lack of fit with existing empirical theory, etc.), any more than an attempted mathematical proof, when it fails, can fail for such reasons.

But that brings us to Churchland’s positive arguments against dualism, which we’ll look at in a third post.

Churchland on dualism, Part IV

Daniel Stoljar’s remarks on dualism, which I criticized in an earlier post, bring to mind some similar remarks made by Paul Churchland in response to Frank Jackson’s famous “knowledge argument” against physicalism. You’ll recall that Stoljar claimed that objections to a physicalist account of intentionality would apply no less to a dualist account. Churchland makes the same claim with respect to qualia – the introspectible features of a conscious experience, in virtue of which there is “something it is like” to have that experience. (Stock examples of qualia would be the way pain feels, the way red looks, or the way coffee tastes and smells.)

Jackson’s argument goes roughly like this. Imagine that Mary, a master neuroscientist of the future, has lived her entire life in a black and white room, never having had any experience of colors. But she knows everything there is to know about the physical facts concerning the physics and physiology of color perception. Thus, though she’s never seen a red object herself, she knows exactly what happens in other people’s eyes and nervous systems when they see red, as well as all the relevant facts about light, surface reflectance properties of red objects, and so on. Eventually she leaves the room and sees a red object for the first time. Does she learn something new? Jackson says she clearly does – she learns what it’s like to see red. And that (so the argument goes) suffices to refute physicalism. For physicalism claims that to know all the physical facts about human beings is to know all the facts about them, period. But though Mary knew all the relevant physical facts about color perception prior to her release from the room, she didn’t know all the facts, because she learned something new upon her release. Hence there is more to human nature than is captured by a description of the physical facts. In particular, facts about qualia (such as the facts about what it’s like to see red) are additional facts, beyond the physical facts.

I will have more to say about the knowledge argument – and in particular about Jackson’s later change of heart about it – in a future post. For now let’s consider Churchland’s objection, which he first stated in his paper “Reduction, Qualia, and the Direct Introspection of Brain States” and repeated in his later paper “Knowing Qualia: A Reply to Jackson.” (Both papers are reprinted in Churchland’s book A Neurocomputational Perspective, which is the source of the quotes below.) In the course of making several other criticisms of Jackson, Churchland says that if the knowledge argument were sound, it would refute substance dualism for the same reasons it would refute materialism. For we need only run the argument by imagining instead that Mary is a master “ectoplasmologist” with knowledge of the “hidden constitution and nomic intricacies” of ectoplasm, and in particular of “everything there is to know about the ectoplasmic processes underlying vision” (“Reduction, Qualia, and the Direct Introspection of Brain States,” p. 63). Since Mary would learn something new upon leaving the room despite knowing everything there is to know about ectoplasm, this parallel argument “would ‘show’ that there are some aspects of consciousness that must forever escape the ectoplasmic story” (“Knowing Qualia,” p. 72, emphasis in the original).

But Churchland is just making the same mistake we saw Stoljar make. What philosophical dualist ever said anything about “ectoplasmic processes,” or about the “hidden constitution” or “nomic intricacies” of an immaterial substance? Even apart from the “ectoplasm” nonsense – which is, of course, just a rhetorical flourish intended to make dualism sound ridiculous before it is even given a hearing – Churchland’s description of dualism is a ludicrous caricature. He makes it sound as if the dualist were committed to the existence of an object which is just like a material object in having various parts arranged in a certain way so as to behave according to law-like regularities, only one made out of some ghostly kind of stuff rather than of matter. But that is precisely the opposite of what a Plato, an Aquinas, or a Descartes actually held. For them, as for philosophical dualists generally, the soul is necessarily something simple or non-composite, and thus without parts of either a material or a quasi-material sort. Hence it has no “hidden constitution” or “nomic intricacies” of the sort Churchland has in mind. It is not a kind of ghostly mechanism because it is not a “mechanism” at all. (True, Descartes was a mechanist, but only concerning the material world, not the mind.)

For the Cartesian dualist, who is Churchland’s immediate target, the essence of the soul is just to think, and thought is (on this view) essentially conscious. As Descartes says in a letter to Mersenne, “nothing can be in me, that is to say, in my mind, of which I am not conscious” (Descartes, Philosophical Letters, p. 90, emphasis in original), and as he writes in the replies to the Second Set of Objections, “thought is a word that covers everything that exists in us in such a way that we are immediately conscious of it” (Haldane and Ross, Philosophical Works of Descartes, vol. II, p. 52, emphasis in original). In the Fifth Set of Objections, Gassendi had complained that Descartes fails to provide an account of the “internal substance” of the mind, which would require something analogous to the “chemical investigation” by which we discover what unseen properties of wine determine its surface features (Cottingham, Stoothoff, and Murdoch, Philosophical Writings of Descartes, vol. II, p. 193). Descartes replied, in words that could have been directed at Churchland: “You want us, you say, to conduct ‘a kind of chemical investigation’ of the mind, as we would of wine. This is indeed worthy of you, O Flesh, and of all those who have only a very confused conception of everything, and so do not know the proper questions to ask about each thing” and (in response to another of Gassendi’s objections) that “your purpose was simply to show us what absurd and unjust quibbles can be thought up by those who are more anxious to attack a position than to understand it” (Ibid., pp. 248-49). For Descartes, your res cogitans isn’t something which, by virtue of some hidden internal constitution, generates your consciousness; your res cogitans just is your consciousness.

For that reason, there can be no “knowledge argument” against substance dualism parallel to Jackson’s argument against physicalism. If the Mary of Churchland’s alternate scenario does not know what it is like to experience red before leaving the room, then she just does not and cannot know everything there is to know about res cogitans, because experiencing red is nothing more than a mode of consciousness and (therefore) a mode of res cogitans. To know everything there is to know about a res cogitans would not involve knowing about its internal constitution, the causal relations holding between its parts, etc. (for it has none of these things) but would involve instead knowing every kind of conscious thought or experience it might have – including experiencing red. The “gap” between two kinds of fact that Jackson’s original argument points to does not have even a prima facie parallel in the substance dualist case. The physicalist has to acknowledge at least a conceptual difference between physical facts and facts about consciousness; the only question is whether there is also a metaphysical difference. But there is, according to the Cartesian dualist, not even a conceptual difference between facts about res cogitans and facts about consciousness. That’s Descartes’ whole point.

Whatever other objections the physicalist might raise against dualism, then, the tu quoque strategy employed by Churchland and many other contemporary materialists is simply incompetent. It rests on a fundamental misunderstanding of what the dualist means by an “immaterial substance.” Equally incompetent is any critique of dualism that treats it (as Churchland evidently does in “Knowing Qualia”) as a kind of quasi-scientific empirical theory – that is, as if it were “postulating” the existence of immaterial substance as the “best explanation” of mental phenomena among the various alternatives. As I noted in a previous post on Churchland, that is not at all what the most significant dualists in the history of philosophy were up to. Their arguments for dualism are intended instead as strict metaphysical demonstrations of the existence of the soul. One may or may not think the attempted demonstrations succeed, but one will not refute them unless one first understands what sort of argument they are intended to be. Dualists traditionally tend to regard metaphysical inquiry as an enterprise every bit as rational as, but distinct from and more fundamental than, empirical science. Committed as they often are to scientism, contemporary materialists would no doubt deny that there can be any such form of inquiry, but they cannot deploy this denial in an argument against dualism without begging the question.

Their unreflective scientism is no doubt one source of contemporary materialists’ systematic misunderstanding of dualism. Since they think all rational inquiry must be a kind of scientific inquiry, they tend to (mis)interpret the claims of dualists (as they often do the claims of theists) as if they were feeble exercises in empirical hypothesis formation. It seems to me that another source might be the enormous influence Gilbert Ryle’s book The Concept of Mind had on mid-twentieth century philosophy. For Ryle there characterized Descartes’ position, absurdly, as a “para-mechanical hypothesis” on which minds are “rather like machines but also considerably different from them,” being “spectral machines” that are “complex organized unit[s]” which run on “counterpart” principles to those of physical substances, “made of a different sort of stuff and with a different sort of structure” which might be thought of “not [as] bits of clockwork [but rather] just bits of not-clockwork” and where the “bits” are arranged into a “field of causes and effects” (pp. 18-20). It is as if Churchland’s generation of materialists got their “knowledge” of what dualists believe from reading Ryle, and the generations since have gotten their “knowledge” from reading people like Churchland.

In any event, the materialist who characterizes the soul in terms of “ectoplasm” is like the atheist who compares the God of classical theism to the “Flying Spaghetti Monster” or thinks that the cosmological argument starts with the premise that “Everything has a cause…” Not to put too fine a point on it, neither one knows what the hell he is talking about or has any business opening his mouth on the subjects in question.

The interaction problem, Part II

In an earlier post, I suggested that one of the advantages of hylemorphic dualism over Cartesian dualism is that its notion of formal causation allows it to sidestep the interaction problem. For if the soul is the form of the body, rather than a distinct substance in its own right, then there is no question of two substances having to “interact” in the order of efficient causes on the model of two billiard balls. There is rather just the one substance, a human being, having (as every other material substance has) two constituents, its form (or soul) and its matter (or body). The “interaction” between them is no more problematic than the “interaction” between the form of a tree and the matter that makes up the tree. For soul and body do not “interact” in the first place the way two distinct things do; they together constitute a single thing. My intention to raise my hand is not one event which has somehow to get into causal contact with another, physical event. It is rather the formal-cum-final cause of a single event of which the activity in my nervous system and arm is the efficient-cum-material cause. The solution to the “interaction problem” is to break out of the conceptual Procrustean bed of the mechanical picture of the world and return to a philosophy of nature informed by Aristotle’s four causes.

(Actually, saying that this “sidesteps” the interaction problem is misleading and anachronistic, since it conveys the false impression that hylemorphic dualism was motivated in part by a desire to solve the interaction problem. In fact there was no interaction problem until early modern philosophers like Descartes abandoned hylemorphism and redefined matter, mind, and causation in an explicitly anti-Aristotelian way. As I show in The Last Superstition, the “mind-body problem,” like the “traditional” philosophical problems of induction, personal identity, causation, and many others, is largely a consequence of the early moderns’ mechanistic revolution.)

Some modern dualists have suggested that the interaction problem is oversold in the first place. And they are right to complain that materialists fling it around much too glibly. To be sure, the interaction problem really is a problem for Cartesian dualism, but it is not (by itself, anyway) a refutation of it. Let’s briefly consider why – before going on to see why it is nevertheless a serious enough problem that any dualist is well-advised to consider opting for hylemorphic dualism over the Cartesian variety (especially given that, as I would argue, there is already ample independent reason to adopt hylemorphism as a general metaphysics).

One reason why the interaction problem does not strictly refute Cartesian dualism is that the Cartesian dualist could always simply deny that mind-body interaction is real in the first place, and opt for occasionalism, or parallelism, or epiphenomenalism. Of course, the extreme oddity of these views leads many critics of Cartesian dualism to regard recourse to them as little better than an admission of defeat, a desperate appeal to a deus ex machina. As Bill Vallicella notes (without necessarily endorsing the judgment) both Malebranche’s occasionalism and Leibniz’s pre-established harmony have been accused of deploying a deus ex machina strategy, especially since both literally appeal to God to resolve the question of the mind-body relationship.

But though the charge is common, it is unfair. Malebranche and Leibniz both had independent philosophical reasons for believing in God, and both also had independent reasons for denying that there could be causal interaction between created substances (any substances, not just mind and body). And given their respective specific understandings of the nature of substances, Malebranche had good reason to think that God continuously mediates between them, and Leibniz to think that God does not do so but instead established a universal harmony between them at creation. Hence, Malebranche quite naturally concluded that (for example) when you decide to have a beer your body moves towards the fridge, not because the decision causes the bodily movement, but because God, on noting that you have made that decision, causes the body so to move. And given his different conception of substance, Leibniz quite naturally concluded instead that the decision and the bodily movement in question were each simply the natural unfolding of what was pre-programmed into each substance at their creation. These views of the mind-body relationship were not developed simply to deal with the interaction problem, but flowed naturally from two sophisticated and independently defensible metaphysical positions.

Defensible, but still bizarre, rarely actually defended, and subject to various objections of their own. And most modern dualists would agree with materialists that it would be preferable to avoid occasionalism and pre-established harmony if one can manage it. Hence the greater popularity of epiphenomenalism, according to which mental events do not cause physical events but are rather merely the ineffectual byproduct of the flux of physical events. When you decide to have a beer, the decision itself (or at least the conscious awareness of it) is not what causes your body to walk over to the fridge. Rather, entirely unconscious physical events caused your body to do so, and in the process also caused the conscious experience of making the decision in question, which event itself had no causal efficacy at all.

Though not much less bizarre than occasionalism and pre-established harmony, epiphenomenalism at least has this advantage over them as a way for Cartesian dualists to deal with the mind-body problem: Materialists too seem led into it, so that they can’t plausibly use it as a stick with which to beat dualists. For materialist theories of mind have a notorious problem explaining the efficacy of mental content. If (as materialists tend to hold) it is only the physical properties of mental states which give them their power to cause other physical states, then their mental or intentional content seems epiphenomenal. For example, if we suppose, as a materialist might, that my decision to have a beer is identical with or at least supervenes upon some event in my nervous system, then if it is only the physiological properties of that event that enter into the explanation of how it caused my bodily movements, the fact that it involved a representation of beer, specifically, or indeed had any representational content at all, drops out as causally irrelevant.

So, if materialists as well as Cartesian dualists are faced with the possibility of having to swallow epiphenomenalism, the former cannot accuse the latter of having a special difficulty in accounting for mind-body interaction. Still, this is more a rhetorical victory for Cartesian dualism rather than a substantive one. For epiphenomenalism is notoriously unsatisfactory, and not just because it is odd to say that your decision to have a beer is not what caused you to go to the fridge. If our mental states can have no causal influence whatsoever on our bodies, it would seem to follow that we cannot even talk about them. Indeed, the epiphenomenalist himself could not even talk about his thoughts about epiphenomenalism. For those thoughts would be as inefficacious as any other mental state or event. When he says “Epiphenomenalism is true,” the fact that he thinks it is true has absolutely nothing to do with his saying so. This is bizarre at best and incoherent at worst. And though epiphenomenalists have tried to find various ways around the problem, it would be better not to have to deal with it in the first place.

So, a Cartesian dualist is well-advised not to deny that mind and body interact. And this brings us to the second reason why a Cartesian dualist has a right to complain that his critics’ appeal to the interaction problem is often too glib. As Bill Vallicella has pointed out in several past posts, whether a Cartesian dualist can account for mind-body interaction depends on what view of causation one is assuming. And there is at least one view of causation – a regularity theory – on which no interaction problem arises at all for Cartesian dualism. As Bill has suggested:

Suppose we say that:

Event-token e1 causes event-token e2 if and only if (i) e1 temporally precedes e2, and (ii) e1 and e2 are tokens of event-types E1 and E2 respectively such that every tokening of E1 is followed by a tokening of E2.

On this Hume-inspired theory (sans the contiguity condition), causation is just regular succession. If this is the correct theory of causation, then there is nothing problematic about mental events causing physical events, and vice versa.

About this, Bill is absolutely right. If such a regularity analysis is correct – and there are philosophers who would defend such an analysis on grounds independent of their position on the mind-body problem – then the interaction problem is solved. At the very least Cartesian dualists can plausibly hold that objections to their position based on the interaction problem are less conclusive than their critics often let on.

But the “if” in question is a very big one. Is such a regularity theory of causation really plausible in the first place, or at least plausible enough to show that Cartesian dualism really can account for mind-body interaction after all? I think not. One reason why is that apart from its use of the word “cause,” the proposed analysis is perfectly compatible in substance with occasionalism, parallelism, and epiphenomenalism. For on each of those views, it is perfectly possible to say that a mental event of type M is always followed by a physical event of type P, in which case, on Bill’s suggested regularity theory, M will count as the cause of P. But an “interactionist” theory which differs in substance not at all from occasionalism, parallelism, or epiphenomenalism – all of which deny interaction – is an “interactionist” theory in name only.

Another problem with the proposed regularity analysis is that it simply doesn’t capture what we mean by “cause.” As Hume himself recognized, the connection we take to hold between a cause and its effect is not just a regular one, but also a necessary one. We don’t just think A was in fact followed by B, but that in some sense it had to be followed by B. Of course, Hume thinks there is no objective source for this idea of necessity, that it has to be traced to a purely subjective expectation on our part. For he holds that there is nothing in our ideas either of a cause or of its effect that necessarily links them together. Objectively speaking, causes and effects are “loose and separate,” and any effect or none could in theory follow upon any cause.

This Humean result is what makes “regularity” theories of causation seem at all plausible. But what they really give us is not causation, but rather only some replacement for causation. (The same holds true, I would say, for counterfactual analyses of causation.) So, no appeal to such a theory really solves the interaction problem at all. Rather, it simply adds one mystery to another, saying, in effect: “Causation in general is already mysterious, so why shouldn’t mind-body interaction be?”

The thing is, the reason causation in general is mysterious is the same reason mind-body interaction in particular is: the mechanistic revolution that displaced the Aristotelian-Scholastic model of explanation, throwing out formal and final causes and trying to make do with bastardized versions of material and efficient causes. As I have noted in earlier posts and discuss at length in TLS, one of the main arguments the Aristotelian tradition gives for formal and final causes is that without them efficient causation becomes unintelligible. Unless there is something in the nature (or “substantial form”) of a thing by virtue of which it “points to” or is “directed at” the generation of a certain effect (as its final cause) then there is no way to account for why exactly it produces that effect as opposed to some radically different effect, or none at all. Hume was merely drawing out the inevitable consequences of the mechanistic revolution. (And even here Hume is, as always, overrated, since the skepticism vis-à-vis causation implicit in the rejection of formal and final causes was already foreshadowed in Ockham and the late medieval nominalist tradition.) The way to solve both the interaction problem and the problem of causation is, accordingly, the same: a return to the Aristotelian metaphysics early modern philosophy displaced.

Some brief arguments for dualism, Part II

Following Aristotle, the Scholastic tradition famously held that final causes – goal-directedness, purposiveness, natural ends – permeate the natural world. Contrary to a popular misconception, this does not mean that they thought that everything in the world has a purpose or function in the sense that biological organs have purposes or functions. Hence it is no good to accuse them of thinking, absurdly, that piles of dirt, asteroids, mountain ranges, and the like simply must play some role within the universe as a whole that is somehow analogous to the role hearts and kidneys play in the body. Functions like the kind bodily organs play constitute only one, relatively rare, kind of final causality. Nor did they think that final causality is generally associated with anything like consciousness. For an Aristotelian to say that a plant by virtue of its nature “wants” to grow is just a figure of speech. Literally speaking the plant does not, of course, want anything at all, since it is totally unconscious. It is only in us, and in certain other animals, that final causes are associated with conscious awareness.

What the Scholastics did have in mind is summed up in Aquinas’s dictum that “every agent acts for an end,” otherwise known as the “principle of finality.” By an “agent” he means that which brings about or causes some effect. And what he is saying is that when a certain cause generates a certain effect or range of effects in a law-like way (as we would say today) that is only because it naturally “points to“ or is “directed towards” that effect or range of effects as its proper end. For example, a match when struck will, unless prevented (e.g. by being water damaged), generate flame and heat – and flame and heat specifically rather than frost and cold, or the smell of lilacs, or no effect at all. It has an inherent causal power to bring about that effect specifically. What Aquinas and the other Scholastics argued is that unless we acknowledge the existence of such inherent powers, unless we recognize that whenever a certain efficient cause A generates its effect B that is only because the generation of B is the final cause or natural end of A, then we have no way of making intelligible why it is exactly that A generates B specifically rather than some other effect or no effect at all. The existence of final causes is, in this sense, a necessary condition for the existence of efficient causes – of, that is to say, causation as modern philosophers tend to understand it. This is one reason Aquinas held the final cause to be “the cause of causes.”

Now modern philosophy, and in particular modern philosophy’s conception of science, is defined more than anything else by its rejection of final causes. Indeed, as philosophers like William Hasker and David Hull have pointed out, at this point in the history of science, what remains of the “mechanistic” picture of the natural world which we have inherited from the early moderns is really nothing but this rejection. As I argue in The Last Superstition, there has never really been any serious philosophical case for this rejection; it was, and still is, more ideologically than intellectually motivated. Moreover, there are in my view (and, again, as I argue in TLS) overwhelming reasons to think it was a mistake. One of them is that, as Hume’s famous puzzles illustrate, causation has indeed become seriously problematic in modern philosophy in exactly the way Aquinas’s analysis would lead us to expect it to, given the abandonment of final causes.

The abandonment of final causes has also crucially contributed to the creation of the “mind-body problem,” something that did not exist, certainly not in anything like the form familiar to contemporary philosophers, prior to the moderns’ rejection of the Aristotelian-Scholastic metaphysical framework. For to insist that the material world is utterly devoid of final causes – devoid, that is to say, of anything that inherently “points to” or is “directed toward” anything beyond itself – is implicitly to deny that intentionality could possibly be material, for intentionality, of course, is just the mind’s capacity to point to or be directed towards something beyond itself, as it does in thought. (See my previous post in this series.) Hence to insist that the material world is devoid of any inherent final causes while at the same time acknowledging the existence of intentionality is implicitly to commit oneself to dualism. Indeed, this is surely one reason why Descartes, one of the fathers of the “mechanistic” revolution in science, was a dualist. Far from being a kind of pre-scientific holdover, dualism of the broadly Cartesian sort is a logical consequence of the turn to mechanism that defined the scientific revolution.

The only way to hold on to the mechanistic conception of nature while rejecting dualism is thus to deny the existence of intentionality. And that is why, as John Searle has argued, all extant forms of materialism do indeed implicitly deny its existence, and thus (I would say) amount to disguised forms of eliminative materialism. This is halfway admitted by Jerry Fodor when he writes, as he does in Psychosemantics, that “if aboutness [i.e. intentionality] is real, it must be really something else.” That is to say, intentionality per se simply cannot be real given the mechanistic conception of the material world that Fodor, like all materialists, has inherited from the early modern philosophers. Hence the most the materialist can do is try to substitute for it some physicalistically “respectable” ersatz. But this is simply eliminative materialism in “folk psychological” drag; and eliminative materialism, however you dress it up, is simply incoherent. (Yet again, see TLS, and in particular chapter 6, for the details.)

We have, then, another brief argument for dualism, which can be summarized as follows: If materialism is true, then (given that it is committed to a mechanistic conception of the material world), there are no final causes, and thus nothing that inherently “points to” or is “directed at” anything beyond itself; and in that case, there can be no such thing as intentionality; but there is such a thing as intentionality; therefore materialism is not true.

This is an argument for dualism, I should say, at least if one admits that the material world exists in the first place (which, of course, everyone other than a few adherents of idealism would admit), because it implies that there are features of the world other than its material features. The only way to avoid the dualistic consequences (other than opting for eliminativism or idealism) would be to acknowledge that the Aristotelians were right after all, and that final causes are a real feature of material reality. But that would, of course, be to abandon the entire modern mechanistic-cum-materialistic interpretation of science. Nor would it really stave off dualism for long, for it would simply open the door to the Thomistic or hylemorphic (as opposed to Cartesian) version of dualism. But that is a story for another time – a story which, like other details of the argument sketched here, can be found (if I might be forgiven one more shameless plug) in The Last Superstition.