Thursday, June 14, 2018

The two Cartesian worlds


The “interaction problem” is traditionally regarded as the main objection to Descartes’ brand of dualism.  I’ve discussed it many times here at the blog, and of course it is addressed in my book Philosophy of Mind.  The problem concerns how a res cogitans or “thinking substance” and a res extensa or “extended substance” can possibly have any causal influence on one another given the way Descartes characterizes them.

There are various ways the problem might be spelled out.  Sometimes it is framed in terms of the idea that it is mysterious how something with no length, width, depth, surface, spatial location, or any other physical attributes (all of which a res cogitans lacks) can get in contact with something that does have such attributes (as a res extensa does).  Sometimes it is framed in terms of the idea that such interaction would violate the law of conservation of energy, insofar as for a res extensa to influence a res cogitans would seem to require the physical world as a whole to lose energy, and for causal influence to go in the other direction would seem to require the physical world as a whole to gain energy.  As I suggested in a couple of relatively recent posts (here and here), the best way to understand the interaction problem is in terms of the idea that the Cartesian conception of mind and body makes their causal relationship comparable to demonic possession, and cannot account for the unity of the human person.

But here’s yet another way to think about it.  The Cartesian conception of mind and body, at least when worked out consistently, arguably makes of res cogitans and res extensa two worlds that are so self-contained and complete that there is simply nothing for either one to do vis-à-vis the other.  Each is like a fifth wheel relative to the other.

Hence, on the one hand, we have the neo-Cartesian notion of a “zombie” (in the philosophical sense of the term) as the natural consequence of the mechanical conception of matter that Descartes, along with other early modern philosophers and scientists, made central to the modern understanding of nature.  I say “neo-Cartesian” because the notion of a zombie is not explicit in Descartes.  But it is implicit, and appeal to it has become a key move in the argumentation of contemporary Cartesians.  Descartes notoriously thinks of non-human animals, which lack res cogitans, as automata, behaving as if they experience pain, pleasure, and other sensations, but in fact devoid of consciousness.  If you add to Descartes’ conception of an animal as an automaton the idea of something which behaves as if it were uttering meaningful speech and as if it were manifesting intelligent behavior but is really just mimicking these things, you essentially have the idea of a zombie – of a creature which is physically and behaviorally identical to a human being but is devoid of any mental properties.  

Part of the reason the mechanical conception of matter entails the possibility of zombies is that it takes matter to be devoid of anything like color, sound, taste, odor, heat, cold and the like, as common sense conceives of these qualities.  On the mechanical conception, if you redefine redness (for example) as a tendency to absorb certain wavelengths of light and reflect others, then you can say that redness is a real feature of the physical world.  But if by “redness” you mean what common sense understands by it – the way red looks in conscious experience – then, according to the mechanical conception, nothing like that really exists in matter.  And something similar holds of other sensory qualities.  The implication is that matter is devoid of any of the features that make it the case that there is “something it is like” to have a conscious experience, and thus is devoid of consciousness itself.

Another aspect of the mechanical conception of nature that entails the possibility of zombies is the thesis of the causal closure of the physical.  The idea here is that everything that happens in the physical world at any one moment of time can be entirely explained in terms of the state of the physical world at an earlier moment of time together with purely physical laws.  (Notice that I said explained by rather than determined by.  You don’t need to be a determinist to hold to the causal closure of the physical.)  Every physical event, on this view, has a physical cause sufficient to account for it.  If this is the case, there is nothing for distinctively mental properties to do, which is why contemporary Cartesians and materialists alike often take an epiphenomenalist position vis-à-vis the mind, according to which mental properties are simply “along for the ride,” as it were, and don’t actually have any efficacy relative to bodily behavior.

The causal closure thesis is arguably the more crucial thesis vis-à-vis zombies, because one could in principle take the view that zombies are possible vis-à-vis phenomenal consciousness but not vis-à-vis rationality.  If one did hold this, then one might in principle argue that while there could be a creature physically and behaviorally identical to us that was not conscious, there could not be one that is physically and behaviorally identical to us that was not rational.  But if we factor in the causal closure thesis, this becomes untenable.  If physical causes suffice to account for everything that happens in the physical world, then that would include apparently rational speech activity and apparently rational behavior.  Actual rational thought processes qua rational (as opposed to qua physical) would be unnecessary.  Hence a zombie devoid even of rationality would be possible.

Then, on the side of res cogitans, we have the Cartesian idea that your mental life could be exactly as it is now even if the entire material world, including your body and brain, were illusory, parts of a hallucinatory deception foisted upon you by a malicious spirit (Descartes’ “evil genius”).  This hypothesis reflects what contemporary philosophers of mind would call a radically internalist theory of mental content, on which the contents of thought and consciousness are determined entirely by factors internal to the mind rather than its relations to anything outside it.

If this radical internalism is correct, then it seems that there is really nothing for the external material world to do vis-à-vis influencing what you think and experience.  We have, in effect, the flip side of the zombie hypothesis.  On the zombie hypothesis, the world is physically identical to our world, but devoid of phenomenology.  On the “evil genius” hypothesis, the world is phenomenologically identical to our world, but devoid of anything physical.  

You can see why the Cartesian thesis that some ideas are innate would naturally develop into the thesis that all ideas are innate, as it essentially did in Leibniz (for whom every monad has all information packed into it upon its creation, and thus needs no “window” onto external reality).  For if the mind could be in any phenomenological state whatsoever even in the complete absence of matter (and thus the complete absence of any mind-independent world or any sense organs with which to make contact with a mind-independent world) then what is needed in order to determine the content of any phenomenological state (and thus any thought or experience) must already be built into the mind.

So, again, the Cartesian picture of reality leaves us with two self-contained worlds.  There is physical reality, which could be exactly as it is in the complete absence of any mental phenomena whatsoever, as in the zombie scenario.  And there is mental reality, which could be exactly as it is in the complete absence of any physical phenomena whatsoever, as in the evil genius scenario.  So what exactly does matter do vis-à-vis mind, and what exactly does mind do vis-à-vis matter?  Interaction becomes problematic because it seems unnecessary.  

This also helps us also to understand more deeply why, as I have often pointed out, there is no interaction problem on an Aristotelian-Thomistic (A-T) conception of human nature, even though it too regards the intellect as immaterial.  For one thing, the A-T position rejects the thesis of the causal closure of the physical.  And the main reason it does so is because the causal closure thesis conceives of causation entirely in terms of what A-T thinkers would call efficient causality.  But efficient causality is only one of four fundamental modes of explanation – the others being, of course, formal causality, material causality, and final causality.  The causal closure thesis also presupposes a reductionist conception of physical objects (never mind the immateriality of the intellect) that the A-T position rejects.  It just gets the basic metaphysics even of the material world badly wrong.  And of course, from an A-T point of view, the Cartesian also gets the metaphysics of human nature badly wrong, starting with the idea that a human being is a mashup of two distinct substances.  There simply aren’t two things in the case of a human being in the first place, on the A-T view, and thus there is no question of how two things “interact.”

Nor does the A-T position have any truck with the internalism and innatism of the Cartesian position, committed as A-T is to the thesis that “there is nothing in the intellect that was not first in the senses.”  Angels have innate ideas, but we don’t.  For example, we need to abstract our ideas of universals like dog, tree, man, etc. from actual concrete particular material things which instantiate those universals – in which there must be concrete particular material things in order for us to have any ideas about them.  Hence there is no sense to be made of our having exactly the phenomenology we have in the absence of any material world.

(Does that mean that angels could be subject to an “evil genius” type hallucination?  No, because Descartes’ scenario involves a kind of sensory experience, and angels don’t have that.  In fact it is not clear that, given A-T premises, we can really make coherent sense of the evil genius scenario.  For the scenario involves sensory experience in the complete absence of anything corporeal.  But if there is no corporeality, there can be no sensory experience; and if there is sensory experience, then there must be corporeality.  The scenario seems possible only if we don’t think about the underlying metaphysics very carefully.)

30 comments:

  1. Quantum Mechanics seems to disagree with the causal closure thesis, insofar as the present state of affairs cannot even in principle be used to determinately predict a future state of affairs.

    Unless I'm misunderstanding the causal closure thesis, of course.

    ReplyDelete
    Replies
    1. Keep in mind, as Ed mentions, that causal closure requires merely an explanation, not some determining state of affairs. So QM wouldn't seem to be a problem here.

      Delete
    2. Feser explicitly uses the term "explained" rather than "determined" in define causal closure. He even provides an aside why he uses "explains". Then it is puzzling why you put the question as if causal closure is a matter of deterministic prediction.

      Also, the indeterminacy of quantum mechanics is precisely in the opposite direction to the sort of freedom that mental beings bring to the physical world as CS Lewis noticed in the book Miracles.

      Delete
    3. The set up of EPR which provided the basis for the Bell inequality proves one of two possibilities: (1) no causality; or (2) no classical values until interaction. But we know there is causality from other places like GPS. Therefore the second possibility is right.

      Delete
    4. But I thought that QM (under the standard interpretation, at least) doesn't merely posit action that is indeterminate but also uncaused and unexplainable.

      Delete
    5. @Tony
      Science cannot tell us what does not exist by what it fails to observe. There's a world of difference between unexplained and uncaused.

      Delete
    6. @tony,
      The standard interpretation of QM is fallacious as Fr Jaki explained -the uncertainty principle equivocates between two different senses of the word "undetermined ". If you read discussions of the uncertainty principle, they are always about inability to measure precisely the momentum of the particle when it position is known precisely and vice-versa
      The fallacy consists in equating this indeterminacy in measurement to the ontological indeterminacy

      Delete
  2. Nice post Dr. Feser,

    Correct me if I am wrong , it seems the reason in support for A-T view and against substance dualism is that, interaction between two substance is problematic but composition isn't or existence of composite objects isn't that much controversial. Or at least it appears that reality of composition is required for A-T view. But it seems that every popular objection to substance dualism has a parallel objection to composition and any reply on behalf of defender of composition can be similarly used in defense of substance dualism ( see Philosopher Andrew Brenner's paper "Mereological Nihilism and Personal Ontology").

    All these considerations of parsimony, conservation laws, causal closure/exclusion,evolutionary debunking, evidence of supervenience etc which are brought against substance dualism can be equally brought against Composition. Like consider Your claim against substance dualism above that those two substances are so self-contained and complete that there is simply nothing for either one to do vis-à-vis the other. Each is like a fifth wheel relative to the other, it seems similar objection can be raised against composition and hence against A-T view (and also non-reductive physicalism) It seems equally mysterious in case of composition that how two sets of object , the parts and whole influence each other, they also seem so self-contained and complete that there is simply nothing for either one to do vis-à-vis the other.,

    So it appears there has to be something wrong with what I've said above, otherwise A-T dualism doesn't seem superior to Cartesian one, these two views seem to be equally plausible or unplausible.

    ReplyDelete
    Replies
    1. Well to deny composition, you essentially have to accept atomism or monism. However, everyday consciousness seems to refute these two alternatives. The unity of consciousness refutes atomism while the denial of our own omniscience (our ability to learn new things outside of ourselves) refutes monism. On the A-T view, substances are composite insofar as they are a composite of act and potency. There is no overdetermination because the parts of a substance are not considered substances but virtual substances. For example, as long as a quark is bound in a proton, it is not really a quark in its own right, but merely a part of a proton. Affecting the one quark affects the whole proton. A quark has the potential to become its own proper substance (although this has never been observed) but it is not actually so.

      Delete
    2. Well to deny composition, you essentially have to accept atomism or monism. However, everyday consciousness seems to refute these two alternatives.

      But these aren't only options as there is Substance Dualism. Just like atoms , a Cartesian Soul is a mereological simple.

      On the A-T view, substances are composite insofar as they are a composite of act and potency................
      ... A quark has the potential to become its own proper substance (although this has never been observed) but it is not actually so.


      Interesting, But isn't this just a denial of composition? Instead of denying reality of whole the reality of parts is being denied here. But maybe something very different is meant by term "virtual existence" than what I am thinking. Is that so?

      Delete
    3. There has been very little scholarly work done on virtual particles in relation to what we now know about quantum physics. This is an area of metaphysics much neglected.

      Delete
    4. A quark has the potential to become its own proper substance

      I was under the impression this was a matter of debate.

      Delete
    5. I’m not talking about virtual particles when I say virtual substance. For example, my left arm is not a substance in its own right. It IS a part of the whole substance which is my body, however. It is a virtual substance insofar as it has the potential to become an aggregate of dead flesh (if it were cut off). The status of protons and quarks is besides the point. It is simply an example. Holism does not stand or fall with emergent properties of protons (although I think there is very strong case for considering protons substances as opposed to aggregates.

      Substance dualism is not a denial of composition. It is saying that there are extended substances and spiritual substances, but it does not necessarily perceive extended substances in atomistic or monistic terms. The point is, I think, that the holism, atomism, monism debate is not particularly relevant to the hylemorphic vs substance dualism debate since they can both concede a holistic metaphysics.

      Delete
    6. @Scott Lynch are you the writer?

      Delete
    7. @Cogniblog What do you mean? I am definitely not the writer of this blog. Edward Feser is. I’m sure he would argue more precisely than me (an amateur), but I am espousing A-T sentiments. And I do not think that Substance Dualism requires atomism or monism. Furthermore, in order for even a monist to deny composition, he basically has to deny change, which substance dualists do not in my experience. Therefore, I do not see the belief in composite substances to be particularly of interest to the hylemorphic vs. substance dualism debate.

      Delete
    8. @Scott Lynch no I mean, are you the fantasy novelist known as Scott Lynch, author of The Gentleman Bastards series?

      Delete
    9. Substance dualism is not a denial of composition. It is saying that there are extended substances and spiritual substances, but it does not necessarily perceive extended substances in atomistic or monistic terms. The point is,

      That is true, its not necessarily a denial of composition in itself but it is still an option for composition denier to accommodate mind and persons in his view. The whole objection to mereological nihilism that it is incompatible with existence of persons is only tenable if Substance dualism is false.

      The point is, I think, that the holism, atomism, monism debate is not particularly relevant to the hylemorphic vs substance dualism debate since they can both concede a holistic metaphysics.

      But it is relevant because one of these is not compatible with mereological nihilism.

      I’m not talking about virtual particles when I say virtual substance. For example, my left arm is not a substance in its own right. It IS a part of the whole substance which is my body, however. It is a virtual substance insofar as it has the potential to become an aggregate of dead flesh (if it were cut off).

      There are questions about this view.
      In what sense do virtual substances exist?
      If virtual substantial parts have the same ontological status as other substances then the term doesn't do any work any we face same kind of problem about relation of parts and wholes.

      Delete
    10. Haha! No I am not. I have heard of him, though.

      Delete
    11. @Red Virtual substances do not have the same ontological status as a true substance. The reason is that a virtual substance is pointing to its relationship to the whole (true substance). For example, the human body is the designated matter directed by the soul. It makes no sense to speak of a body without a soul (for them it would be a mere aggregate of dead flesh). That it must reference the whole does not mean that it is not real or really a part of the person in question. It does do some ontological work insofar as it gives an incomplete explanation of the capacities of a substance. However, it cannot be made sense of without the whole substance. For example, the behavior of an electron in a helium atom cannot be made sense of without reference to the other electron and the nucleus (its spin is constrained via the Pauli Exclusion Principle, for example. The bound electron (virtual substance) behaves very differently than a free electron (substance). Someone denying holism would have to refute these very convincing “emergent” phenomena for virtually all substances in the world before verifying monism or atomism. The holist needs only a single example to prove his point.

      As for substance dualism permitting merelogical nihilism (rejection of composition) via denial of the reliability of the senses, I think that is an uphill battle. Even once you concede substance dualism, you still have to accept the cold reality of the unity and composition of conciousness. Our conscious experience gives witness to composition. I have a left field of vision and a right field, and I am aware of them both at the same time. I am also aware of sounds, smells, etc. This unified composition seems to refute any kind of immaterial atomism (like a Russelian neutral monism, perhaps). The fact that we learn things and forget things seems to refute monism. How could a single substance experience accretion and diminution if it is the totality of existence? The composition denier this does not seem to benefit much from his dualistic position.

      Delete
    12. @ Scott Lynch

      Some very nice points, lot to think about, later.

      For now do you think some of what you say can also be brought in defense of non-reductive physicalism ?

      This above problem also seem to affect it as it too requires composition to be real, it seems.

      Delete
    13. @Red Yes, most arguments for holism could be given for non-reductive physicalism, which is really a type of holism. To refute the physicalism, you would have to make some sort of argument for the immateriality of the intellect or of God. Consciousness (at least as far as sensation and phantasms are concerned, is a material process on the hylemorphic analysis (which is why physical states such as intoxication can deprive us of consciousness). Furthermore, even our immaterial intellect relies on our material bodies. So the hylemorphic dualist needs to argue that the intellect can do things over and above what can be explained by any indeterminate physical state (using the definition of determinacy from philosophy of mind). And I think Edward Feser has a particular expertise in that field of argumentation.

      Delete
  3. Well, is the brain in the vat (evil genius+some material world) a possibility in the A-T framework? Can it be disproven for certain? Imo it doesn’t seem like it can be disproven but it amounts to no importance practically speaking.

    ReplyDelete
  4. According to Aquinas, the intellect moves the will as a final cause, but the will moves the intellect as an efficient cause (in this case, an agent):

    "I answer that, A thing is said to move in two ways:

    "First, as an end; for instance, when we say that the end moves the agent. In this way the intellect moves the will, because the good understood is the object of the will, and moves it as an end.

    "Secondly, a thing is said to move as an agent, as what alters moves what is altered, and what impels moves what is impelled. In this way the will moves the intellect and all the powers of the soul, as Anselm says (Eadmer, De Similitudinibus). The reason is, because wherever we have order among a number of active powers, that power which regards the universal end moves the powers which regard particular ends. And we may observe this both in nature and in things politic... Now the object of the will is good and the end in general, and each power is directed to some suitable good proper to it, as sight is directed to the perception of color, and the intellect to the knowledge of truth. Therefore the will as agent moves all the powers of the soul to their respective acts, except the natural powers of the vegetative part, which are not subject to our will." (S.T. I, q. 82, art. 4)

    It is thus incorrect to claim that the soul only moves the body as a final cause. Something has to move my arm when I decide to raise it. And St. Thomas seems to be saying that my act of will is what makes my arm go up.

    ReplyDelete
  5. Most atheists/naturalists subscribe to reductionist/emergentist materialism. Their view of matter is not dissimilar to that of Descartes, but they view the mind as somehow being "produced" by matter, whether they want to describe that "production" as "reduction" or "emergence" or whatever. They usually are aware of Cartesian substance dualism, and often have reasonable grounds for rejecting it, including grounds like those Dr. Feser describes here. Most of them however are largely ignoring any alternatives to materialism or substance dualism, hylemorphic dualism included.

    I think, to get from materialism to something like Berkeleyan idealism, is maybe not going that far. A reductionist materialist can just choose to swap the direction of the arrow of reduction–instead of reducing mind to matter, start reducing matter to mind. Materialism and idealism are (to some extent) mirror images of each other, so I think that means the distance from one to another is relatively small.

    On the other hand, hylemorphic dualism requires the acceptance of a whole lot of A-T metaphysics, such as substance-accident theory, moderate realism, the four causes, etc. It is a lot further away from reductionist materialism than reductionist idealism is. It is a very different way of thinking. And, I think from a sort of apologetic perspective, it may be much easier to convert a reductionist to a different form of reductionism (idealist rather than materialist), than to convert them to the A-T worldview. (Certainly, I managed to convert myself to a different form of reductionism, I am still unconvinced by A-T.)

    ReplyDelete
    Replies
    1. @Simon As a reductionist, how would you explain the unity of consciousness?

      Delete
  6. I am with you, Simon.

    Hylemorphic dualism seems to be fairly successful as a model for understanding the world. I don't think it is so successful in giving an ontological explanation of things. In particular it breaks down precisely where it seems to be most needed: in anthropology. What I mean is this: The general scheme of hylemorphic dualism is that form provides the whatness of things, while what individuates is matter. When we get to anthropology, we are told (a) that the soul/mind/spirit is the form of the human being, while the body is its matter and (b) the soul/mind/spirit is what individuates the human being, its haecceity, so to speak. I find it hard to fit this into the general Hylemorphic scheme.

    I also have problems with moderate (immanent) realism regarding universals which seem to me unable to bear the weight of being both the formal cause of things, and also of being the epistemic cause of our knowledge of things. To me, only transcendent realism can do both of these at the same time.

    I have come to view matter (philosophical matter, that is) as an unnecessary addition to ontology. The will and knowledge of God are sufficient to instantiate that which He wills to be: we do not need in addition to posit some prima materia which somehow becomes signata when participated by a form. Physical matter, is, of course something for empirical research, but it does not need philosophical matter to underpin it in addition to the underpinning of the will and knowledge of the Deity: which is in itself sufficient to cause the being of anything that is.

    Or so it seems to me.

    ReplyDelete
    Replies
    1. It is not quite correct to say that for human being "the body is its matter".
      Body is composed of matter and informed by the form.
      However, your larger point stands. There is a fatal equivocation in hylemorphic anthropology regarding human soul. Is it a universal "rational animal" kind of thing or a particular soul or spirit of a particular human being?

      Delete
  7. A question I have regarding thomistic dualism is that if the soul is immaterial and hence immortal, and if the soul is the form of the living human body, why is the body not also naturally immortal in accordance with its form?

    ReplyDelete
    Replies
    1. @Anonymous for the same reason the vegetative soul survives non-lethal amputations, and yet body parts can still be lost via amputation. The soul is an organizing principle, but it needs something to organize. So the dog soul needs the matter of the arm to organize and give power to the material arm. Once the arm is lost, the soul still “wants” to organize and give power to the arm, but there is nothing there to be organized. If the dog gets an arm transplant, the soul will then be able to take over again. For the human soul, death is like a full body amputation. The soul “wants” to organize and give power to a material body, but there is nothing to empower. It does not die however because it has faculties that transcend matter (intellect and will). However, these faculties are greatly diminished (without divine action) because they are so reliant on matter in this life (for sense images, etc.). Now when a dog dies, the soul does not remain because there is no higher faculty of the dog soul apart from organizing the matter of the dog. Once the matter is disintegrated enough for death, there is nothing left for the soul to be the soul of. In humans, after death, the soul is still the soul of our intellectual and voluntary faculties.

      Is that helpful?

      Delete
  8. I hope to get to Aquinas someday. In the meantime I am not sure understand why the answer to the mind body problem should not be simple, that is people have a soul. As Allan Bloom made note of that after the Enlightenment people became secular. So the problem is the Mind body problem --not the mind soul problem.

    ReplyDelete