Chomsky on the mind-body problem

I am, to say the very least, not a fan of Noam Chomsky’s writings on politics and foreign policy. But his straightforwardly philosophical work is always interesting and important even when one disagrees with it. A case in point is his view of the traditional mind-body problem. The usual assumption is that we have a clear understanding of what matter is, and that the difficulty has to do with explaining how thoughts, sensations, and other mental phenomena relate to material processes in the nervous system. Are the former identical to or supervenient upon the latter? Various anti-materialist arguments purport to show that they cannot be either, which seems to entail some form of dualism. But in that case we face the interaction problem. In any event, the “body” side of the mind-body problem is usually taken to be unproblematic; it is mind that raises the puzzles, or so it is thought.

Chomsky rejects this assumption. In his view, “body” is as problematic as mind; so much so that we do not even have a clear idea of what the mind-body problem is. As he writes in Language and Problems of Knowledge: The Managua Lectures:

The mind-body problem can be posed sensibly only insofar as we have a definite conception of body. If we have no such definite and fixed conception, we cannot ask whether some phenomena fall beyond its range. The Cartesians offered a fairly definite conception of body in terms of their contact mechanics, which in many respects reflects commonsense understanding. Therefore they could sensibly formulate the mind-body problem… (p. 142)

[However] the Cartesian concept of body was refuted by seventeenth-century physics, particularly in the work of Isaac Newton, which laid the foundations for modern science. Newton demonstrated that the motions of the heavenly bodies could not be explained by the principles of Descartes’s contact mechanics, so that the Cartesian concept of body must be abandoned. (p. 143)

In other words, when we think of causation in the natural world as Descartes did – that is, as involving literal contact between two extended substances – then the way in which a thought or a sensation relate to a material object becomes mysterious. Certainly it cannot be right to think of a thought or sensation as making literal physical contact with the surface of the brain, or in any other way communicating motion in a “push-pull” way. But when we give up this crude model of causation, as Newton did, the source of the mystery disappears. At the same time, no systematic positive account of what matter as such is has ever really been put forward to replace Descartes’ conception. Hence, Chomsky continues:

There is no longer any definite conception of body. Rather, the material world is whatever we discover it to be, with whatever properties it must be assumed to have for the purposes of explanatory theory. Any intelligible theory that offers genuine explanations and that can be assimilated to the core notions of physics becomes part of the theory of the material world, part of our account of body. If we have such a theory in some domain, we seek to assimilate it to the core notions of physics, perhaps modifying these notions as we carry out this enterprise. (p. 144)

That is to say, we have in Chomsky’s view various worked-out, successful theories of different parts of the natural world, and we try to integrate these by assimilating them to “the core notions of physics,” but may end up altering those core notions if we need to in order to make the assimilation work. As a result, as Chomsky once put it to John Searle, “as soon as we come to understand anything, we call it ‘physical’” (quoted by Searle in The Rediscovery of the Mind, p. 25). But we have no conception of what is “physical” or “material” prior to and independently of this enterprise. And since the enterprise is not complete, “physical” and “material” have no fixed and determinate content; we simply apply them to whatever it is we happen at the moment to think we know how assimilate into the body of existing scientific theory. As a consequence:

The mind-body problem can therefore not even be formulated. The problem cannot be solved, because there is no clear way to state it. Unless someone proposes a definite concept of body, we cannot ask whether some phenomena exceed its bounds. (Language and Problems of Knowledge, p. 145)

Hence, while Chomsky is no dualist, neither does he embrace the standard alternatives: “There seems to be no coherent doctrine of materialism and metaphysical naturalism, no issue of eliminativism, no mind-body problem” (New Horizons in the Study of Language and Mind, p. 91). In short, if the problem has no clear content, neither do any of the solutions to it. Chomsky’s preferred approach, it seems, is just to carry on the task of developing and evaluating theories of various aspects of the mind and integrating them as one can into the existing body of scientific knowledge, letting the chips fall where they may vis-à-vis the definition of “physical” or “material.”

What should we make of this? Chomsky is, I think, absolutely right to emphasize that the concept of matter is no less problematic than that of mind, and that this entails that “materialism” and “physicalism” are far less determinate in content than their adherents typically suppose. (This is something Bertrand Russell also emphasized, as do later philosophers of mind influenced by him, such as Grover Maxwell, Michael Lockwood, Galen Strawson, and David Chalmers.) At the same time, I think it is clear that the concept of the “physical” or the “material” is not in fact as elastic as Chomsky’s remarks might imply, either in the thinking of most scientists or in that of philosophical naturalists.

It is true that the positive content of the notion is fairly indeterminate, subject to fluctuation with every change in the physical sciences. But there is a core of negative content that is more or less fixed. That is to say, whatever matter turns out to be, there are certain features that modern philosophers, and scientists in their philosophical moments, tend to refuse ever to attribute to it.

For at least some of them, this would seem to include sensory qualities like color, odor, taste, sound, and the like as common sense understands them. For the mechanistic revolution Chomsky alludes to was not merely, and indeed not even essentially, committed to the idea that material causation involves literal contact. It was also and more lastingly committed to some variant or other of a “primary/secondary” quality distinction on which there is nothing in the material world that “resembles” our “ideas” of the sensory qualities mentioned (as Locke would put it). If we want to redefine the “red” of a fire engine in terms of how its surface reflects photons at certain wavelengths, we can say that the fire engine is red. But if by “red” we mean the way red “looks” to us when we perceive it, then nothing like that exists in the fire engine, which is (if we think of color in these commonsense terms) intrinsically “colorless.” And so on for sounds, tastes, and all the rest. Color, odor, taste, sound, and the like – again, as common sense understands them (rather than as redefined for purposes of physics) – are reinterpreted by mechanism as projections of the mind, existing only in consciousness. This is the origin of the “qualia problem,” and the puzzle now becomes how to relate these “qualia” or “phenomenal properties” to the intrinsically colorless, odorless, tasteless particles that make up the brain just as much as they do external material objects.

Now if one insists on denying these sensory qualities to matter, then it seems clear that we do have a clear enough conception of “body” to generate a mind-body problem. More than that, we have a conception that clearly implies that the mind (in which alone these qualities exist) cannot be something material or bodily – that, at any rate, is the lesson drawn by early modern thinkers like Cudworth and Malebranche, and by contemporary writers like Richard Swinburne, who take the “mechanistic” conception of matter itself to entail dualism. (I have discussed this issue before in several places, e.g. here, here, and in The Last Superstition.)

A naturalist could, however, decide to reincorporate the sensory qualities into the material world by conceiving of them as the intrinsic properties of matter, which “flesh out” the abstract mathematical structure described by physics. And this is precisely the move made by the writers influenced by Russell whom I mentioned above – Maxwell, Lockwood, Strawson, and Chalmers. To be sure, the resulting position is hardly “materialist” or “physicalist” as those terms are usually understood; some of these writers describe it instead as neutral monist, or panpsychist, or even as a variety of dualism. But they also tend to regard it as nevertheless consistent with a kind of naturalism, even if what is allowed to count as “natural” is thereby expanded considerably. (An exchange between Strawson and Chomsky can be found in Louise Antony and Norbert Hornstein, eds., Chomsky and His Critics.)

There is, however, another, more fundamental and indeed absolutely “non-negotiable” component of the mechanistic picture of the world inherited from the early modern philosophers, one well-known to regular readers of this blog: the rejection of Aristotelian formal and final causes. As I have argued in many places (such as in this recent post, as well as in The Last Superstition and Aquinas), this is the surviving and definitive element of the mechanistic revolution, and the one which naturalists seem to take, either explicitly or implicitly, to be crucial to their position. Whatever else the physical world may turn out to be like, and whatever alterations might be made to scientific practice, the mechanist, and the naturalist, are committed to the view that there is no such thing as goal-directedness or teleology intrinsic to the natural world, and that proper scientific procedure ought never to posit such immanent teleology. (See the quotes in the post just linked to for examples of philosophers who endorse this conception of science.)

If this is correct, then we once again have a conception of matter, albeit a negative one, which is determinate enough to generate a mind-body problem. If nothing in the material world inherently points beyond itself as to an end or final cause, then it is hard to see how that aspect of the mind philosophers call intentionality – the way that a thought “points to,” is “about,” or is “directed at” something beyond itself (such as the way your thought about the Eiffel tower is “about” or “directed at” the Eiffel tower) – can possibly be given a “naturalistic” explanation. As I have argued in several places (e.g. here) a dualism of intentional phenomena and material phenomena seems unavoidable given a mechanistic conception of nature, even if the Russellian naturalist can avoid a dualism of qualitative phenomena and material phenomena by expanding his conception of the “natural” (though even that is not a sure thing).

As Jerry Fodor puts it in Psychosemantics: The Problem of Meaning in the Philosophy of Mind:

I suppose that sooner or later the physicists will complete the catalog they’ve been compiling of the ultimate and irreducible properties of things. When they do, the likes of spin, charm, and charge will perhaps appear on their list. But aboutness surely won’t; intentionality simply doesn’t go that deep. It’s hard to see, in face of this consideration, how one can be a Realist about intentionality without also being, to some extent or other, a Reductionist. If the semantic and the intentional are real properties of things, it must be in virtue of their identity with (or maybe of their supervenience on?) properties that are themselves neither intentional nor semantic. If aboutness is real, it must be really something else. (p. 97)

Of course, Fodor’s “Reductionism” is not really the only option. One could combine Realism about intentionality with dualism instead; or with idealism; or with Aristotelian hylemorphism. But the last of these positions would indeed be ruled out if one agrees with Fodor about what the physicists’ ultimate catalog must look like, and the other two options would certainly be incompatible with at least most naturalists’ understanding of “naturalism.” In any event, the passage illustrates the point that contemporary philosophers do have a determinate enough conception of matter (albeit a negative one) to generate a mind-body problem: Fodor’s point is that given the conception of the physical to which he and like-minded philosophers are committed, intentionality becomes philosophically problematic. The passage illustrates also that the naturalist seems bound at the end of the day to deny the existence of intentionality given his conception of matter. For to say that “if aboutness is real, it must be really something else” is just a cute way of saying that aboutness is not real, and must be replaced in our ontology by some physicalistically “respectable” ersatz. As Searle has complained (e.g. in the book cited above), materialist “reductions” of this or that mental phenomenon never really succeed in “reducing” it at all, but either change the subject or implicitly deny the existence of the phenomenon. Reductionist versions of materialism are really just disguised forms of eliminative materialism.

That is a big topic, but suffice it for now to emphasize two points. First, while Chomsky is right to say that modern philosophers’ conception of “matter” or “the physical” is far less determinate than they often suppose, it is in fact determinate enough to generate a real mind-body problem. Second, the mechanistic assumptions underlying this determination of their conception of matter are, contrary to what they (and Chomsky himself, I imagine) typically suppose, not “scientific” at all, but purely philosophical – and (as my regular readers know) in my view deeply mistaken.

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 questions on the soul, Part III

In some recent posts I’ve been answering readers’ questions about the Aristotelian-Thomistic (A-T) understanding of the soul.  One more for the road, from a reader who is unclear about why mind-body interaction, which is notoriously problematic for Cartesian dualism, is not also problematic for A-T.  The reader writes:

[U]nless something like dualist interactionism is true, I don't see how… immaterial thoughts and - in particular - the will - could possibly cause me to do something as simple as typing this e-mail…

Science would seem to say that the efficient cause of this was certain electrochemical reactions in my body.  The material cause would be the physical events happening in my body.  It seems that A-T philosophy would hold that the final cause was getting an answer to a philosophical question, and I agree.  My soul would then be the formal cause, but I guess that notion is incoherent to me… And, unless the immaterial mind somehow interacts with my body (through quantum physics, maybe?), I don't see how my thinking about something in my immaterial intellect could cause my body to do anything.

Descartes’ “clear and distinct perception” argument

The “clear and distinct perception” argument is one of two arguments for mind-body dualism Descartes gives in the sixth of his famous Meditations on First Philosophy. It can be summarized as follows:

1. Whatever I have a clear and distinct idea of is capable of existing just as I understand it, at least in principle (e.g. if God creates it that way).

2. I have a clear and distinct idea of myself as simply a thinking, non-extended thing.

3. I have a clear and distinct idea of my body as simply an extended, non-thinking thing.

4. So I and my body are capable, at least in principle, of existing apart from each other.

5. So I am distinct from my body.

Does the argument work? Most contemporary philosophers would say No. I would say No and Yes and No.

Huh? Bear with me.

Here’s the first “No” part. For one thing, Descartes is, by all accounts, wrong to think of extension as the essence of matter, and thus as the essence of the human body. From an Aristotelian-Thomistic perspective (which is my perspective) there is obvious reason to reject this view, since A-T rejects the entire modern mechanistic conception of matter of which it is just a variation. But even those who accept this mechanistic conception – which includes almost all contemporary philosophers, even if (usually) only implicitly and unreflectively – would allow that “extension” (i.e. those properties of matter which can be defined geometrically, more or less) is too crimped a way of spelling out the mechanistic idea. They would allow all sorts of other mathematically quantifiable properties to feature in our characterization of matter as well. (What they share with Descartes is the insistence that, whatever matter is, formal causes and, especially, final causes will simply not be allowed to count as part of the material world.)

For another thing, A-T would also obviously reject Descartes’ implied assimilation of the self to the mind. Though the mind (specifically the intellect) is immaterial, “I” am nevertheless not distinct from my body from the A-T point of view, certainly not without serious qualification. In fairness to Descartes, he did not – contrary to the standard caricature (one now being vigorously combated by Descartes scholars) – actually hold that the body is non-essential to a human being, as if we were all really just ghosts trapped in machines (to allude to Ryle’s famous parody). He explicitly denies that “I” am in my body the way a pilot is in a ship, as if the body were an inessential excrescence. On the contrary, he believed that soul and body form a kind of organic unity, that a human being was an irreducible composite of the two, having attributes (namely appetites, emotions, and sensations) which cannot be predicated of either the soul alone or the body alone. The trouble is that, having abandoned the Aristotelian idea that the soul is the form of the body, and emphasizing as he does that it is the ego itself (and not just some part of the person) which is distinct from the body, he had a devil of a time explaining just how such an organic unity was possible. Hence it is no surprise that the “ghost in the machine” conception of human nature came to be seen as paradigmatically Cartesian, whatever Descartes’ own intentions. (Notoriously, what a thinker wants to conclude is not always what his premises actually imply.)

So, to the extent that Descartes’ argument depends on these assumptions, it is open to criticism. But it can fairly easily be fixed up to avoid these problems. For “myself” in step 2 and “I” in steps 4 and 5, just read “the mind” or (more exactly – and as we’ll see in a moment, as much in line with Descartes’ understanding of the mind as with the A-T view) “the intellect.” For “extension” just plug in either the Aristotelian view of matter or your favorite mechanistic conception. (It makes no difference for this specific argument.) Even if the resulting argument does not get us to precisely Descartes’ brand of dualism, it will definitely get us to some form of dualism, if it is otherwise unobjectionable.

Is it otherwise unobjectionable? Here we come to the “Yes” part of my initial reply. The main objection contemporary philosophers have to Descartes’ argument concerns its second premise, and it is an objection Hobbes raised in the Third Set of Objections to the Meditations. Even if it is conceded that Descartes has a clear and distinct idea of himself as a thinking thing, how can he be so sure that that which is doing the thinking is non-extended or, more generally, non-corporeal? The fact that he doesn’t conceive of corporeality when he conceives of thinking doesn’t show that thinking isn’t corporeal, any more than conceiving of triangularity without conceiving of trilaterality shows that something could be triangular without being trilateral.

So, Descartes needs some way of showing that thought can occur in the absence of anything corporeal or bodily. How about (after the fashion of some contemporary dualists) an appeal to metaphysical possibility, in particular to possible worlds? As in: “It is metaphysically possible for the mind to exist apart from the body” or “There is at least one possible world where mind exists apart from the body”? Nix that. From an A-T point of view, anyway, while these statements are perfectly true, they presuppose dualism and thus cannot be used to establish it. You cannot know what is possible for a thing, or what it might be like in various possible worlds, until you know its nature or essence. (Contemporary philosophers who try to define essence in terms of possible worlds thus have things backwards.) Hence, you cannot assert that there is a possible world in which mind exists apart from body, or that it is metaphysically possible for mind to exist apart from body, until you know the mind’s nature. And its nature is exactly what the Hobbesian objection calls into question.

A better way to show that thought can be incorporeal is just to show that it cannot be corporeal. This is a better way for two reasons. First, it establishes an even stronger claim than the one in question – always nice work if you can get it. Second, it is easy to do.

The reason is one we have examined in several earlier posts (such as this one). The objects of the intellect are abstract concepts, which are universal rather than particular, and determinate or exact rather than indeterminate or inexact. And the thoughts in which these concepts feature are (at least often) as universal, determinate, and exact as the concepts themselves. Yet nothing material has or can have these characteristics. Material objects and processes are inherently particular rather than universal, and also inherently indeterminate or inexact. Hence thoughts cannot possibly be identified with anything material. The point can be and has been developed at greater length (by writers like James Ross, and by me in The Last Superstition and Philosophy of Mind and in the earlier post just linked to) but the basic idea is fairly simple, is as old as Plato and Aristotle, and was endorsed and developed by various Scholastic writers.

The irony is that Descartes himself at least hints at this very argument when, earlier in the Sixth Meditation, he draws a rigid distinction between imagination on the one hand – which he apparently takes to be corporeal – and intellect on the other, which alone he identifies with the self he takes to be incorporeal. (The famous example of the chiliagon – which the intellect understands even though the imagination cannot form an image of it – is presented in this context.) This parallels the Aristotelian-Scholastic doctrine that intellect is immaterial while sensation and imagination are material. It is often supposed that Descartes assimilates sensation, imagination, and intellect into an amorphous something called “the mind,” but this is not the case. His view of their relationship is actually fairly close to that of his Scholastic predecessors. Here as elsewhere Descartes is, as contemporary Descartes scholars have made an industry of documenting, far more Scholastic than one would expect the Father of Modern Philosophy to be. (If only he had been consistently Scholastic, he would have really had something! – though he would not have had this claim to paternity. But we’d all have been better off, and Descartes could have spared himself a few millennia in purgatory.)

The thing is, once this Platonic-Aristotelian-Scholastic point has been developed in support of (our reformulated version of) premise 2, it more or less establishes dualism all by itself, so that the rest of the argument becomes otiose. Hence, Descartes’ argument works, but only if reformulated to such an extent that it amounts to little more than a restatement of an idea that had more or less already been around for millennia. The distinctively Cartesian bits – the stuff about “clear and distinct perception,” the assimilation of the self to the intellect, and the conception of matter as extension – are either wrong or irrelevant. So, as a Cartesian argument for dualism, the argument doesn’t really work after all. What is true in it isn’t new, and what is new isn’t true.

How typically modern!

Descartes’ “indivisibility” argument

In the sixth of his Meditations on First Philosophy, Descartes writes:

[T]here is a vast difference between mind and body, in respect that body, from its nature, is always divisible, and that mind is entirely indivisible.  For in truth, when I consider the mind, that is, when I consider myself in so far only as I am a thinking thing, I can distinguish in myself no parts, but I very clearly discern that I am somewhat absolutely one and entire; and although the whole mind seems to be united to the whole body, yet, when a foot, an arm, or any other part is cut off, I am conscious that nothing has been taken from my mind; nor can the faculties of willing, perceiving, conceiving, etc., properly be called its parts, for it is the same mind that is exercised [all entire] in willing, in perceiving, and in conceiving, etc.  But quite the opposite holds in corporeal or extended things; for I cannot imagine any one of them [how small soever it may be], which I cannot easily sunder in thought, and which, therefore, I do not know to be divisible.  This would be sufficient to teach me that the mind or soul of man is entirely different from the body, if I had not already been apprised of it on other grounds.

Fodor’s trinity

What is the mind-body problem? In an article summarizing his work, which he wrote for Samuel Guttenplan’s A Companion to the Philosophy of Mind, Jerry Fodor answers as follows:

[S]ome of the most pervasive properties of minds seem so mysterious as to raise the Kantian-sounding question how a materialistic psychology is even possible. Lots of mental states are conscious, lots of mental states are intentional, and lots of mental processes are rational, and the question does rather suggest itself how anything that is material could be any of these.

For Fodor, then, there are really three mind-body problems: the problem of consciousness, the problem of intentionality, and the problem of rationality. Why are the phenomena in question problematic?

Let’s look at each briefly. (The following characterizations are mine, not Fodor’s.) When light strikes your retinas, a complex series of neural processes is initiated which may result in one of a range of possible behaviors – taking steps to avoid an obstacle, sorting red apples from green ones, or saying “It’s sunny outside.” When light strikes an “electric eye” or photodetector of some sort, electrical processes are initiated which also may result in one among a range of possible behaviors – the setting off on an alarm, for example, or, if the device is associated with a robot, perhaps behavior similar to the sort you might exhibit, such as avoiding an obstacle, sorting objects, or declaring (through a speech synthesizer) that it is sunny. Now, in the case of the electric eye and its associated robot, what we can observe going on in the system is presumably all there is. The system has no “inner life” or conscious visual experience associated with the electrical activity and behavior. But we do have conscious awareness; we do have an “inner life.” There is “something it is like” for us to see things, whereas there is nothing it is like for the robot to “see” something. Or as contemporary philosophers like to say, we have qualia while the robot appears not to. So, what accounts for this difference? It does not seem plausible to hold that it can be accounted for merely in terms of the greater complexity of the human brain, because the difference between conscious systems and unconscious ones seems clearly to be a difference in quality and not merely of quantity. This is the problem of consciousness.

Then there is the problem of intentionality, which concerns, not just intentions, but meaning in general. (The technical term “intentionality” derives from the Latin intendere, which means “to point at” or “to aim at,” as a word or thought points to or aims at the thing that it means.) Suppose we say that within the robot of our example there is a symbolic representation that means that it is sunny outside. Though the representation has this meaning, it has it only because the designers of the robot programmed the system so that it would be able to detect weather conditions and the like. The electrical processes and physical parts of the system would have had no meaning at all otherwise. By contrast, the thoughts of the designers themselves have meaning without anyone having to impart it to them. As John Searle has put it, the robot’s symbolic representations – like words, sentences, and symbols in general – have only derived intentionality, while human thought has original or intrinsic intentionality. What can account for the difference, especially if we assume that human beings are no less material than robots? That, in a nutshell, is the problem of intentionality.

Consider also that we are able not only to have individual meaningful thought episodes, but also to infer to further thoughts, to go from one thought to another in a rational way. This is not merely a matter of one thought causing another; a lunatic might be caused to conclude that mobsters are trying to kill him every time he judges that it is sunny outside, but such a thought process would not be rational. Rather, we are able to go from one thought to another in accordance with the laws of logic. Now, it might seem that the robot of our example, and computers generally, can do the same thing insofar as we can program them to carry out mathematical operations and the like. But of course, we have had to program them to do this. We have had to assign a certain interpretation to the otherwise meaningless symbolic representations we have decided to count as the “premises” and “conclusion” of a given inference the machine is to carry out, and we have had to design its internal processes in such a way that there is an isomorphism between them and the patterns of reasoning studied by logicians. But no one has to assign meaning to our mental processes in order for them to count as logical. So, what accounts for the difference? How are we able to go from one thought to another in accordance, not just with physical causal laws, but in accordance with the laws of logic? That is the problem of rationality.

Most contemporary philosophers of mind would, I think, agree with Fodor that this trinity of issues constitutes the mind-body problem, and I think they would also more or less agree with my statement of the problems. They do not necessarily agree about how difficult the problems are. Of the three, the problem of rationality seems to get the least attention from contemporary philosophers. Fodor himself thinks that this problem is the one contemporary philosophers have most plausibly been able to solve in a way that vindicates materialism, and that they have done so (contrary to what my statement of the problem suggests) precisely by thinking of rational thought processes as computational processes over formal symbols encoded in the brain. Most other contemporary philosophers of mind seem to agree with Fodor about this much, though there are prominent dissenters, such as Searle, Dreyfus, and defenders of the anti-materialist “argument from reason.” The greatest of the ancient and medieval philosophers would have sided with the dissenters; for Plato, Aristotle, Aquinas, et al., rationality was the aspect of human nature that could not possibly involve a material organ. (We will come back to this point.)

Contemporary philosophers, by contrast, are obsessed with the problem of consciousness, and in particular with “qualia” – something you do not see the ancients and medievals worrying about at all, certainly not as something that pointed to any immaterial aspect of human nature. Fodor, like many other contemporary philosophers of mind, regards this as “the hard problem” for materialism. The problem of intentionality also gets a lot of attention from contemporary philosophers. My sense is that in general they tend to find it more challenging than the problem of rationality but not as challenging as the problem of consciousness. My own view is that, at least as contemporary philosophers tend to understand the problem, it is in fact as great or even greater a difficulty for materialism than the problem of consciousness is. The ancients and medievals would, I think, have agreed, though they would have regarded the problem as pointing to an immaterial aspect of human nature only to the extent that it overlaps with the problem of rationality.

The reason for all this is that the problems of consciousness and intentionality, as they are understood by modern philosophers anyway, are not (as they are often assumed to be) “perennial” problems of philosophy, but rather an artifact of certain historically contingent metaphysical assumptions early modern philosophers like Descartes, Hobbes, Locke, and Co. put at the center of Western thought. In particular, they are an artifact of the “mechanistic” revolution I have discussed and criticized so frequently on this blog and in my books The Last Superstition and Aquinas.

I have explained how this is so at length, both in those books and in previous posts, but here is a brief summary. On the older, Aristotelian-Scholastic understanding of the natural world that the early modern thinkers overthrew, qualities like color, sound, odor, taste, heat and cold were taken to exist in the material world more or less in just the way common sense supposes that they do. The moderns, reviving the view of the ancient atomists, denied this: For them, the natural world is made up of intrinsically colorless, odorless, soundless, tasteless particles in motion, and the qualities in question exist only in the mind of the observer. For purposes of physics, we can in their view redefine heat and cold in terms of molecular motion, or red and green in terms of the different surface reflectance properties of physical objects, but heat, cold, red and green as common sense understands them exist only in consciousness. But since the brain is on this view made up of inherently colorless, odorless, tasteless particles no less than any other physical object, this seems inevitably to entail that consciousness is not a feature of the brain – which is, of course, exactly what Descartes, Malebranche, Locke, and other early modern thinkers concluded insofar as they embraced dualism. Therein lies the origin of what contemporary writers call the “qualia problem” or the problem of consciousness.

The older, Aristotelian-Scholastic view also held that a kind of meaning, teleology, or goal-directedness is built into the structure of the material world from top to bottom. This includes not just the usual examples – the functions of bodily organs – but basic causal relations as well. For the Scholastics, if some cause A predictably generates some specific effect or range of effects B, this can only be because A inherently “points to” or “aims at” B. Generating B, specifically – rather than C, or D, or no effect at all – is what Aristotelians would call the “final cause” of A. Causing B is what A will naturally tend to do unless impeded. Now the early moderns eliminated final causality from their picture of the natural world; this was and has remained the core of a “mechanistic” conception of nature. For them there is no teleology built into nature, no purposiveness or goal-directedness. There are brute, meaningless cause and effect patterns, but no reason inherent in nature why a cause should have just the effects it does have. One result of this was to open the way to the puzzles about causation raised by David Hume. More relevant to our interests here, though, is that it made intentionality particularly problematic. If nothing in the material world inherently “points to” or “aims at” anything else – if matter is comprised of nothing more than inherently purposeless, meaningless particles in motion – then, since the brain is made up of these particles no less than any other material object is, it seems to follow that the intentionality of our thoughts, that by virtue of which they inherently “point to,” “aim at,” or mean something beyond themselves, cannot be any sort of material property of the brain. Thus is generated the problem of intentionality.

So, Fodor’s trinity of “mind-body problems” very much reflects a modern set of assumptions about the nature of the physical world. It also reflects a presumption of materialism insofar as Fodor, like so many other contemporary philosophers, writes as if the question to ask were “How do we explain these phenomena in material terms?” Of course, a modern dualist would say that these phenomena cannot be explained in material terms, so that the right question to ask is “Given that these phenomena are not material, how are they related to material phenomena? For example, do they interact causally with them, and if so, how?” You might say that what the mind-body problem is is in part determined by how one thinks it should be solved. (“But how does positing immaterial mind-stuff explain things any better?” A common materialist retort, but not a good one, for reasons I have explained here and here.)

Notice also that Fodor says nothing about the “body” side of the mind-body problem – as if matter were unproblematic and only mind posed any philosophical difficulties. As I have noted recently, a number of prominent contemporary philosophers have emphasized that this is by no means the case. And from an Aristotelian-Scholastic point of view, the moderns’ standard assumptions about matter are perhaps even more problematic than their assumptions about mind. “Qualia” can seem necessarily immaterial only if we assume that matter is as the ancient atomists and their modern successors assume it to be; the “qualia problem,” which many modern materialists regard as such a challenge to their position (as Democritus himself did) is a problem that their own favored conception of matter created. The same is true of the problem of intentionality, at least if that is taken essentially to involve the problem of how something material can “point to” or be “directed at” something else. From an Aristotelian-Scholastic point of view, since matter is not as the atomists take it to be, and immanent final causality or teleology pervades the material world from top to bottom anyway, there is no special difficulty in regarding qualia and (at least many instances of) intentionality as in some significant sense “natural” or even “material” phenomena.

Things are very different, though, where intentional phenomena having a conceptual structure are concerned, as well as where reasoning is concerned. Here is where the Aristotelian-Scholastic tradition locates an immaterial element to human nature. The reason, in a nutshell, is that the objects of our thoughts are universal rather than particular, and determinate or exact rather than indeterminate or ambiguous; that the thoughts themselves inherit this universality and determinacy; and that nothing material can possibly be universal and determinate in this way. This is, of course, a very large topic deserving a discussion of its own. I have explored it in more detail in earlier posts (e.g. here and here) as well as in chapter 4 of Aquinas and chapter 7 of Philosophy of Mind. (The most thorough recent defense of the line of thought in question is probably the one offered in the late James Ross’s article “Immaterial Aspects of Thought.”)

The “dualism” that results is very different from the Cartesian variety, though. For the mind (or more precisely, the intellect) is not a substance on the Aristotelian-Scholastic view, but rather a power of the soul, and the soul in turn is not a substance either (or at least not a complete substance) but rather the substantial form of the living human body. Neither is the body a substance. It is rather only soul and body together which make a complete substance, where soul and body are just one instance among innumerable others of the hylemorphic form/matter relationship that exists in every material substance. Accordingly, there is no “interaction problem” of the sort that faces the Cartesian. Such a problem arises when we think of the mind as an “immaterial substance” (or as a collection of “immaterial properties”) which must somehow interact with a (mechanistically-defined) material substance via what Aristotelians would call efficient causation. But from an Aristotelian-Scholastic point of view, that is simply a category mistake, or rather a collection of category mistakes. Intellect is rather one of a myriad of powers the soul imparts to the human animal of which it is the substantial form. Thus it is formal causation which relates soul (and therefore mind) to body, not efficient causation. (I have discussed this issue in more detail here, here, and here.)

All of this is bound to sound very odd to the average contemporary philosopher. It will not sound odd, though, to those familiar with the rich conceptual apparatus of the Aristotelian-Scholastic tradition, a system of thought of which most contemporary philosophers of mind are ignorant, or at best know only through the caricatures peddled by early modern philosophers. Working one’s way out of the metaphysical assumptions moderns typically bring to bear on these issues is very difficult and takes time; the temptation is always to try to translate the thought of a Plato, an Aristotle, or an Aquinas into categories contemporary philosophers are familiar with, when what we ought to be doing is recognizing that it is precisely those categories the ancients and medievals would challenge. Thus are Plato the “proto-Cartesian,” Aristotle the “functionalist,” and other ahistorical Frankenstein monsters created. (I had not sufficiently freed myself of such modern assumptions when I wrote Philosophy of Mind, in which there is still too much Cartesianism. Chapter 4 of Aquinas provides a corrective, and a more detailed treatment of how thoroughly wrong contemporary philosophers of mind get the conceptual lay of the land, from an Aristotelian-Thomistic point of view.)

So, from an Aristotelian-Scholastic point of view, the materialist’s “problem” of explaining the three purported kinds of mental phenomena in material terms (where “matter” is understood mechanistically) and the Cartesian’s “problem” of explaining mind-body interaction are pseudo-problems. In short, while for Fodor and other contemporary philosophers of mind there are three mind-body problems, for the Aristotelian-Scholastic philosopher, there is no mind-body problem at all.

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.

Conceiving and hallucinating

The “conceivability argument” for dualism holds that (1) it is conceivable that I might exist apart from by body, and therefore that (2) it is metaphysically possible for me to exist apart from my body, so that (3) I am not identical to my body. I put forward a detailed and sympathetic exposition of this argument in chapter 2 of Philosophy of Mind – for it is more interesting and defensible than some philosophers give it credit for – but I do not in fact endorse it. It is essentially a variation on Descartes’ “clear and distinct perception” argument for dualism, and as I’ve argued elsewhere, what’s true in that argument isn’t new and what’s new isn’t true. (As an Aristotelico-Thomist I reject the rationalist assumptions inherent in Descartes’ version, and the Kripke-style modal assumptions inherent in modern versions. But demonstrating the mind’s immateriality does not require committing oneself to these assumptions.)

But as I say, the argument is more defensible than it is often given credit for. Take the thought experiment I discussed in Philosophy of Mind, W. D. Hart’s “seeing without a body” example. (Hart develops this example in his book The Engines of the Soul and in his article “Dualism” in Samuel Guttenplan, ed., A Companion to the Philosophy of Mind. Follow the links and you can read the relevant sections online via Google books.) Hart asks you to imagine that you wake up one morning, look in the bathroom mirror, and see staring back at you two empty eye sockets where your eyeballs used to be. This is no doubt physically impossible, but it does seem that we can at least conceive of having such an experience. There is no apparent contradiction or incoherence in the idea. Seeing without eyeballs is thus arguably metaphysically possible even if it is not physically possible.

Hart then asks us to extend the thought experiment in various ways. For example (and as I suggested extending it in the book) you might imagine that instead of seeing two empty eye sockets staring back at you, what you see in the mirror is the stump of your neck where your head used to be – a headless body, arms raised in horror. Seeing without a head, and thus without a brain, seems perfectly conceivable, then, and therefore (by the reasoning of the conceivability argument) at least metaphysically possible even if not physically possible. And if that is conceivable, so too is it conceivable to have the experience of seeing without arms, legs, torso, or any body at all; in which case (the argument claims) it is metaphysically possible to see without a body. But since seeing is a kind of mental state, it is therefore metaphysically possible to have a mind without a body.

Now, to evaluate the conceivability argument, we have to determine (a) whether what seems to be conceivable in this case really is conceivable, (b) whether conceivability really does entail metaphysical possibility, and (c) whether the metaphysical possibility of A existing without B really does entail that A and B are non-identical. I commend Hart’s discussion of these various issues (and also my discussion in Philosophy of Mind) to the interested reader. What I want to focus on here is just (a), and in particular on one possible challenge to (a).

A friend of mine sometimes reads this blog at work. (“I’m that bored,” he explains.) He’s been reading Philosophy of Mind, and when I saw him the other day he asked vis-à-vis the Hart example: “What does that prove? Isn’t it just obvious that I would be hallucinating?” That’s a fair question. We might put the objection this way: For the conceivability argument to work, we have to be able to show that (among other things) it really is conceivable to see without a body. But Hart’s example shows at most only that it is conceivable that we might have an experience that seems like the experience of seeing without a body. And that’s not good enough, because such an experience might be hallucinatory. “Seems like” does not entail “really is.” Therefore, “We can conceive of it seeming like such-and-such is the case” does not entail “We can conceive of such-and-such really being the case.”

But I think the objection fails. The reason is that hallucination seems parasitic on veridical experience in a way that ensures that if we can conceive of hallucinating something, it follows that we can conceive of really experiencing it. Consider that it isn’t just impossible to conceive of seeing a round square. It is also impossible to conceive of hallucinating a round square. And this is so, surely, precisely because it is impossible to conceive of seeing one. Hallucinating (or visually hallucinating, anyway) is just a kind of defective seeing. So, what’s impossible for seeing in general is impossible for hallucinations in particular. But then, if it were impossible for us to see without a body, it would also be impossible for us to hallucinate seeing without a body. So, since the Hart example at least shows (by the objector’s own admission) that the latter is possible, that suffices to show that the former is possible as well.

Or so it seems to me. The conceivability argument may or may not fail on other grounds, but I think that at least to this extent it is on solid ground.

Vallicella on hylemorphic dualism

Hylemorphic dualism is the approach to the mind-body problem taken by Aquinas and the Thomist tradition more generally.  (The label may have been coined by David Oderberg, who defends the view in an important paper and in his book Real Essentialism.  “Hylemorphic” is sometimes spelled “hylomorphic,” though the former spelling is arguably preferable since it is closer to the Greek root hyle.)  The view holds both that the soul is the substantial form of the living human body (that is the “hylemorphic” part) and that it is unique among the forms of material things in being subsistent, that is, capable of surviving beyond the death of the body (that is the “dualism” part).  Our friend Bill Vallicella has recently put forward the following criticism of the view:

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.

The interaction problem, Part III

In a couple of previous posts (here and here) we have examined the famous “interaction problem” facing Cartesian dualism and its origins in the impoverished conception of causation the early modern philosophers put in place of the Aristotelian-Scholastic conception. But as Bill Vallicella rightly notes, whatever we think of the interaction problem and of Cartesian dualism’s ability to deal with it, it cannot be regarded as a reason for preferring materialism to dualism. For materialism faces an interaction problem of its own.

Part of the problem is that even if we identify mental events and physical events, mental properties seem to have no causal relevance. Suppose a sensation of pain is identical with such-and-such a neural firing pattern. The way it causes you to moan and to nurse the damaged body part is by triggering further neural processes which result in the flexing of the relevant muscles. In that case, though, it is the electrochemical properties alone that are doing the causal work, and the distinctively mental aspect – the experienced phenomenal character of the pain itself – seems epiphenomenal. This is called the “mental causation problem” and it is the aspect of the interaction problem for materialism that Bill focuses on. It arises in different ways for different varieties of materialism. (It threatens Donald Davidson’s anomalous monism, for example, because of his principle of the anomalism of the mental.)

But this isn’t the only way the interaction problem arises for materialism. It arises also because the mechanistic conception of the natural world makes body-body interaction as mysterious as mind-body interaction. And again, it does so because of the impoverished conception of causation the moderns put in place of the older Aristotelian-Scholastic conception.

The Aristotelian-Scholastic account of causation was rich in theoretical subtleties and carefully worked out distinctions. It included, not only the famous doctrine of the four causes – formal, material, efficient, and final – but also the act/potency distinction, the notion that causes and effects can sometimes be simultaneous, the distinction between causal series ordered per se and causal series ordered per accidens, the distinction between primary and secondary causes, the idea that causation involves the cause communicating something to its effect, an emphasis on substances rather than accidents or events as true causes, and so forth. But as Kenneth Clatterbaugh notes in The Causation Debate in Modern Philosophy 1637-1739, in the century or so between the time of Descartes’ work on the subject and that of Hume, virtually all of the characteristic theses of the Aristotelian-Scholastic account of causation were gradually abandoned. Of the four causes, only efficient causation was left, and in a radically modified form. Substances and their inherent causal powers were abandoned and causation was regarded instead as a relationship between events. Nothing was taken to be communicated from cause to effect and in principle anything might follow upon anything else.

What resulted, naturally, were the skeptical puzzles of Hume. The notion of causation as an objective feature of the world became problematic at best and unintelligible at worst. As I argue at length in The Last Superstition and Aquinas, and have discussed more briefly in earlier posts (e.g. here and here), this was inevitable given the abandonment of final causality. If there is nothing in a cause that inherently “points to” or is “directed at” the generation of a certain effect or range of effects, there is ultimately no way to make sense of the fact that it does indeed generate just that effect or effects.

Hence the fact that a material cause brings about just the material effect or effects it does becomes no less mysterious on the modern, mechanistic account of nature than mind-body interaction does. This is the reason bizarre theories like occasionalism and pre-established harmony had the cachet they did among some of the early moderns. The motivation was not, as is sometimes supposed, to find a way to salvage mind-body dualism. It was rather to find a way to deal with the fact that any causation at all in the natural order – even that between material bodies – seemed impossible given the new conception of nature.

But haven’t many contemporary philosophers tried to solve the puzzles about causation raised by the early modern philosophers, especially Hume? Indeed they have, but as I have shown in TLS and Aquinas, when they have attempted to provide a realist account of causation, the tendency has been to appeal to notions – inherent causal powers, “physical intentionality,” dispositions, and so forth – which essentially involve a return to something like an Aristotelian conception of nature. Clatterbaugh cites the example of Wesley Salmon, who in Four Decades of Scientific Explanation argues that genuine causal processes involve a “transmission” of “information,” and even of “structure,” from cause to effect. Like some of the other contemporary writers I’ve cited before (Armstrong, Molnar, et al.), Salmon does not realize that he sounds like a Scholastic.

The “interaction problem,” then, is not a problem for Cartesian dualism per se but for modern metaphysical positions in general, including materialism. Accordingly, its existence has no tendency whatsoever to provide an argument in favor of materialism over dualism. What it does provide is an argument in favor of a broadly Aristotelian-Scholastic metaphysics over any modern, mechanistic would-be replacement.

The interaction problem

Aristotle and the Scholastic tradition influenced by him famously held that to understand a thing required knowing each of its four causes: its material cause, the stuff out of which it is made; its formal cause, the specific form or essence that stuff has taken on, and which makes it the kind of thing it is; its efficient cause, that which brought it into existence; and its final cause, the end or purpose toward which it is directed. Modern thought is largely defined by its rejection of two of Aristotle's four causes. For the moderns, there are no such things as substantial forms or fixed essences, and there are no ends or purposes in nature. There are just brute material elements related by purposeless, meaningless, mechanical chains of cause and effect.

As I have emphasized in my series of posts on dualism, this “mechanical” conception of nature, insofar as it stripped matter of anything smacking of either goal-directedness or sensible qualities as common sense understands them, and relocated these features into the mind, more or less automatically entailed a Cartesian form of dualism on which intentionality and qualia are immaterial as a matter of conceptual necessity. But it also automatically entailed that this form of dualism would suffer from the notorious “interaction problem.”

For the moderns, all causation gets reduced to what the Aristotelians called efficient causation; that is to say, for A to have a causal influence on B is for A either to bring B into being or at least in some way to bring into existence some modification of B. Final causality is ruled out; hence there is no place in modern thought for the idea that B might play an explanatory role relative to A insofar as generating B is the end or goal toward which A is directed. Formal causality is also ruled out; there is no question for the moderns of a material object’s being (partially) explained by reference to the substantial form it instantiates. We are supposed instead to make reference only to patterns of efficient causal relations holding between basic material elements (atoms, or corpuscles, or quarks, or whatever).

Thus, if the mind considered as immaterial is to have any explanatory role with respect to bodily behavior, this can only be by way of some pattern of efficient causal relations – to put it crudely, in terms of a Cartesian immaterial substance (or perhaps various immaterial properties) “banging” into the material substance (or material properties) of the brain like the proverbial billiard ball. How exactly this is supposed to work is notoriously difficult to explain. We’ve got two independently existing objects (or two independently existing sets of properties) somehow interacting the way physical particles or billiard balls do, or perhaps the way waves or fields of force do – except that one of these objects (or sets of properties) is utterly devoid of any of the material features that make it possible for something to count as a particle, billiard ball, wave, or field of force. Add to this considerations like the conservation of energy and interaction between the material and immaterial realms comes to seem ruled out in principle by our current understanding of the way the material world works.

But from an Aristotelian-Scholastic point of view, this whole picture of the mind-body relationship is hopelessly wrongheaded from start to finish. It is wrong to think of the soul (of which the intellect is for Aristotelians but a part, not the whole) and the body as independent objects in the first place. The soul is rather a form that informs the matter of the body and the body is the matter which is informed. As with the form and matter of a stone, tree, or earthworm, what we have here are not two substances interacting via efficient causation, but rather two metaphysical components of one substance related by formal causation. As the form of the stone is to the matter making up the stone, the form of the tree to the matter making up the tree, and the form of the earthworm to the matter that makes up the earthworm, so too is the human soul to the human body. There is in principle no such thing as the matter of a stone, tree, or earthworm apart from the form of a stone, tree, or earthworm respectively, and no such thing as the form of any of these things existing apart from their matter. The form and matter don’t “interact” as if they were two distinct objects; rather, the form constitutes the matter as the (one) kind of object it is in the first place.

Similarly, there is in principle no such thing as the matter of a living human body without a human soul and there is in principle no such thing as a human soul which is not the soul of some body. (This does not entail that the soul cannot survive the death of the body, only that it could not have existed in the first place unless it was united to some body; but this is a topic that can be bracketed off for present purposes.) The soul doesn’t “interact” with the body considered as an independently existing object, but rather constitutes the matter of the human body as a human body in the first place, as its formal (as opposed to efficient) cause.

As I move my fingers across the keyboard, then, what is occurring is not the transfer of energy (or whatever) from some Cartesian immaterial substance to a material one (my brain), which sets up a series of neural events that are from that point on “on their own” as it were, with no further action required of the soul. There is just one substance, namely me, though a substance the understanding of which requires taking note of each of its formal-, material-, final- and efficient-causal aspects. To be sure, my action counts as writing a blog post rather than (say) undergoing a muscular spasm in part because of the specific pattern of neural events, muscular contractions, and so forth underlying it. But only in part. Yet that does not mean that there is an entirely separate set of events occurring in a separate substance that somehow influences, from outside as it were, the goings on in the body. Rather, the neuromuscular processes are by themselves only the material-cum-efficient causal aspect of a single event of which my thoughts and intentions are the formal-cum-final causal aspect. There is simply no way fully and accurately to describe the one event in question without making reference to each of these aspects. Just as there is no such thing as the matter of a stone or tree apart from the form of a stone or tree, there is no such thing as the “physical” side of my action apart from the “mental” side. To make reference to the “physical” side alone would simply be to leave out half of the story, and indeed the most important half, just as describing the word “cat” in a way that makes reference to the shapes of the letters, the chemicals in the ink in which it is written, and so forth, while never saying anything about the meaning of the word, would leave out the most crucial part of that story.

As psychologist Jerome Kagan emphasizes in his recent book An Argument for Mind (my review of which can be found here) the trouble with trying to pick out some particular pattern of neural or other physiological events and identify some mental event with it (or in any other way attempt entirely to explain the mental in terms of the physiological) is that the same physiological pattern can underlie different mental events and the same mental event can be associated with different physiological patterns. This is a problem well-known to students of the history of the mind-brain identity theory (cf. Davidson’s anomalous monism), though it seems to me that many philosophers do not appreciate just how deep the problem goes, and how thoroughly devastating it is to materialism. As writers like James F. Ross have argued, at least some of our mental states are determinate in a way that no material process or set of processes can be even in principle, so that the hope of making mental states out to be identical with or supervenient upon physical states is an illusion. Without formal and final causes, it is inevitable that the project of assigning some specific, determinate mental content to this or that material substrate will come to grief. (Thus does the interaction problem arise in a new form even for materialists themselves, under the guise of the “mental causation problem.”)

Hence there can, on an Aristotelian-Scholastic view, be no question of some uniquely identifiable set of physiological events with which an independently identifiable set of mental events needs somehow to be correlated in efficient causal terms. There is just the one event of writing the blog post, of which the formal, material, efficient, and final causal components are irreducible aspects. The question of "interaction," in the relevant sense, simply cannot even get off the ground. As is so often the case with objections raised against modern defenses of traditional philosophical views (such as theism and natural law ethics), the interaction problem facing Cartesian forms of dualism arises precisely because these forms of dualism are modern, precisely because they take on board certain modern (especially mechanistic and/or nominalistic) assumptions which they (like theists and natural law theorists) ought instead to repudiate.

I have said much more about all of this in Philosophy of Mind and (especially) The Last Superstition, and I will say more about some of these issues in further posts to come in my series on brief arguments for dualism. The point for now is just to highlight that what we have here is yet another respect (among a great many others that I describe in detail in TLS) in which the early modern philosophers’ transition away from Aristotelianism to a mechanical understanding of nature constituted not an advance but a regression, a willful forgetting of crucial distinctions and categories the drawing and elucidation of which had been one of the great achievements of Scholasticism, and a conceptual impoverishment that inevitably created problems rather than solved them. The interaction problem was by no means the least, or last, of these problems.

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.