The Difficulties of Dualism

Today I would like to write about dualism and the origins of the mind-body problem. Dualism is of course a view that comes in quite a number of different forms, but Descartes’ form was two-way interactionist dualism. He himself did not allow the existence of the mind-body problem, much less discover or invent it. He wrote, in one of the Replies to Objections, that ‘The whole problem contained in such questions arises simply from a presupposition that is false and cannot in any way be proved, namely that, if the soul and the body are two substances whose nature is different, this prevents them from being able to act on each other’ [my italics]. Descartes’ actual role was to describe the mind and the body with their “principal attributes” so precisely that the mind-body problem was forced on the sharper of his readers, in particular Princess Elisabeth of Bohemia and Gassendi. It is to them that the discovery of the mind-body problem should be credited. But Descartes should share in their Nobel Prize (or maybe the Tang Prize, for the reign of the Tang Dynasty during which gunpowder, as distinct from Nobel’s dynamite, which is a high explosive, was invented), as Descartes did the groundwork in his very precise descriptions of the relevant elements: linear extension and consciousness. But Elisabeth was then able to write, ‘You utterly exclude extension from your notion of soul.’ The problem was that something that does not live in the world of linear extension cannot interact with it, because interaction involves effects (“propulsion”) or transfer of energy, and this in turn involves contact, which presupposes spatial location and therefore extension. There is also the question how something lacking linear extension can make its mark on something possessing linear extension. Gravity, it should be noted, does have position and linear extension; there’s a lot of it between the Earth and the Sun, and it weakens as you get further away from massive bodies. So by Descartes’ criterion gravity is full-bloodedly physical.

I have always liked dualism, except that it doesn’t work, for much the reasons Elisabeth and Gassendi gave. Dualisms today, such as E.J. Lowe’s, just cover up the problem. But there it is, lying in wait for the unwary, even those to whom David Duffy drew attention in his Comment yesterday, “who have been exposed to computers all their life”. The existence of computers might tempt these people to think that the mind-body problem can be solved by comparing the mind to the program and the brain to the hardware. The plain difficulty is that though the program is computational, it is straightforwardly physical in Descartes’ sense, the arguments of the early functionalists and today’s artificial intelligentsia notwithstanding.  Even Stockfish, a program rated at 3378 (Magnus Carlsen is 2802), can’t yet think, even about chess, in any interesting sense other than “compute”.

The reason, I think, that I rather like dualism is that it does preserve the distinction between the psychological and the physical. There is a big difference between saying that something is red, and something reflects light of a dominant wavelength of 6.5 x 10-5 cms. There just is such a difference. And differences of this sort seem to remain, whatever the physical description is. It doesn’t have to be dominant wavelength, which is anyway a psychological concept. It could be something behavioural. But all such descriptions are consistent with the absence of red. You could have something that satisfied them and yet there is no red anywhere near that thing. So far so good, but this is just a claim about phenomenal properties, things like colours, or sounds, or heat, and so on. Some philosophers, like me, call the phenomenal properties “qualia”, but others reserve the term for properties of experience itself, so that it is false that apples are red, but true that experiences are. We have here something that doesn’t help much with the mind-body problem, except that our solution to the mind-body problem, must respect the distinction between the physical and the phenomenal.

On the other hand the various forms of dualism are hard to believe. Interactionist dualism doesn’t give a satisfactory account, of all things, of interaction! This is where the generation of philosophers right after Descartes realized that in spite of his enormous contribution, he had got things wrong. And so this generation of philosophers, remaining true to dualism, tried non-interactionist forms, such as occasionalism, and the pre-established harmony. There is a form of dualism that I think has not received enough press, and I’m not sure what it should be called, but “correlationism” suggests itself. There are certain neurons firing in the visual cortex, say, and then there are sensations of red. When we have one set of events, it is followed by the other set. This is a form of interactionism, I suppose, but with the causality really stripped down to its Humean essentials. You could easily write it with INUS conditions, and have a perfectly intelligible story. The difficulty, I think, is to understand why this sort of event (the neurons firing) should lead to just this sort of experience (the sensation of red). The psychophysical correlation remains inexplicable, and this is the difficulty of dualism rearing its ahead again, in a darker form.


  1. Soupie

    One interesting note about the MBP (or HP) is that some people seem incapable of grasping it. It would be interesting to read an analysis of this. Could it be that some people are incapable of escaping Naive Realism and thus cannot imagine a phenomenon being immaterial? Or is it possible that some people conceive of physical processes in an immaterial way and therefore see no interaction problem?

    I’ve been wondering lately if there is a connection between the problem of unifying the mind and body, and the problem in physics of unifying quantum physics and classical physics.

    One key might be Naive Realism and our tendency—as you noted in the previous entry—to think about things in our physicalist ways. To assume that reality just is as we perceive it to be. That is, as ultimately nothing but billiard balls smashing into one another.

    It seems that the HP and QM are pointing us toward a reality that is less classical and material than we typically experience it (heh) to be.

    • Jonathan Westphal

      It is interesting what you write. Why are some people constitutionally unable to grasp MBP or HP? I struggle very hard _not_ to grasp them, or to ungrasp them, beavering away at the categories and concepts involved and hoping to weaken their grip (the grip of MBP and HP), for example by thinking about the muddle of concepts we use: qualia, qualities, phenomenal properties, cogitationes, percepts, raw feels, sense-data, properties of sense-data, ideas, and so on. I think the role of naive realism is very – well, real. We think of visual perception as a causal process ending up in the visual cortex, as a series of physical events, and then try to tack on the subsequent percept or whatever at the end. The result is tears before bed, of course. It won’t work. It came to me very late indeed to reach your realization that the problem is, in your words, “unifying the mind and body”. That is a surprise to me, but a good one.

  2. David Duffy

    “The program is computational, it is straightforwardly physical” – yes, but it allows us a physicalist dualism of matter and information, along with the causal efficacy of the “concrete abstraction” of a mathematical algorithm affecting and being affected by the world. The functionalist would point to the fact there are millions of ways to organise the physical matter of the computer’s memory which are identical with respect to computational outcome. As to Stockfish, I was quite taken by someone quoting the Buddhist epigram in this context: “thoughts without a thinker”. Anyway, not really the place to rehearse all this, which you will discuss later.

    • Jonathan Westphal

      We had the dualism between matter and information well before we had the concept of computation, i.e. well before say 1936. The simple fact is that the same information or proposition can be written in orthographically completely different ways, most obviously in two different languages. About Stockfish, if you think there is thinking going on with Stockfish, what’s the barrier to saying that it’s Stockfish that thinks? There is no other plausible candidate.

      • David Duffy

        But not a full fledged physics of information in non-equilibrium systems. In the case of Stockfish, I think we recognize that it is carrying out an act that we can associate with our own mental life, even though it is a fragment or idiot savant compared to us. So I think that “thinker” has too much baggage (not least panpsychic), but I might say causally efficacious thought is occurring within the computer Stockfish is running on. I think a causal connection to the rest of the world doing work is necessary to avoid dancing pixies type arguments.

        • Jonathan Westphal

          All true. I agree. Genuine information is a bit special, and I like your dualism. “Causally efficacious thought” is occurring, perhaps, but I would worry about cases where the line of analysis of the computer is genuinely new. Nobody has thought these thoughts before, if thoughts is what they are, and none of the programmers nor even the whole team of programmers can even get close to beating Stockfish. But this dualism of information v physical won’t get you phenomenal properties, though I think it has a better shot at intentionality, the other big bugbear for physicalism.

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