A serious challenge for dualism is explaining how mind and body interact if they are made of ontologically different substances, and more specifically how mental phenomena can causally drive bodily events and reactions. Even Descartes, who established dualism in its modern form, acknowledged this problem and famously tried to explain it with his description of the function of the pineal gland.

It seems to me that this would be an even bigger challenge for a modern Dualist (such as David Chalmers, Saul Kripke or Thomas Nagel), given the advances that have been made in neuroscience and physiology. Yet, while the above mentioned authors present all sorts of "gap" arguments for dualism - all of the form: "Dualism obtains because physicalism fails to explain this or that aspect of consciousness" - none of them seem to address the challenge I mentioned to Dualism.

Have any modern Dualists addressed the mind-body interaction problem? How so?

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    Determinism especially has hit a key citadel of dualism. With determinism, we no longer have mental causation in the sense that the mental freely causes things, but simply the interaction of physical systems, of which the brain is one. Now the dualist can't argue for how mind can influence matter because the materialist can point out that it doesn't; it's all causal interactions and mind is an epiphenomenon with no causal effect.
    – R. Barzell
    Commented Oct 20, 2015 at 15:55
  • Why exactly is mental-physical interaction any more problematic than physical-physical interaction? Commented Mar 15, 2016 at 3:03
  • Wow, Kripke was a dualist? Commented Nov 7, 2016 at 12:56
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    Just a note. Descartes was ambivalent about mind-body dualism. He recognised that in some sense they are a unity. People tend to forget this.
    – user20253
    Commented Jul 22, 2017 at 15:14
  • The whole problem evaporates if we assume that dualism is false, while the problem strongly implies that it it is false. Mind and Matter cannot be explained without a third term. This is surely obvious after two millennia of analysis. Those who endorse non-dualism do not face these riddles and obstacles.
    – user20253
    Commented Nov 17, 2017 at 14:13

5 Answers 5


Believe it or not, but the biggest challenge to dualism does not come from neuroscience or physiology, and in fact is shared with materialism, it is the threat of epiphenomenlism. Whether mental is ideal or material it is clearly something successfully used in empirical reasoning. Neuroscience and physiology at this point are in the early preliminary stages of approaching what it is, how it comes to be, or even what the physical correlates of qualia, etc. are. Attempts to explain it away in functionalist terms largely failed. With that reductive materialism is unattractive, and non-reductive materialism and dualism are essentially equivalent for all empirical purposes. It really makes no difference if one thinks that mental is physical but there are no laws reducing the former to the latter (Davidson, Searle), or if one thinks that they are fundamentally different.

There is some sentimental aversion to letting mental causally affect physical, as in dualism, because of an air of mysticism, perhaps, but no one has a problem with letting physical affect mental. And if both are allowed to affect each other we might as well count them both as material, or ideal, or as idealizations of some unifying stuff, as Bergson suggested, or reduxes of some qualitatively different from both stuff, as Russell once held. The last position is called neutral monism. In 19th century many had doubts as to whether electromagnetic field was matter, some courts even ruled that stealing electricity is not stealing, because electricity is not material.

The above sentiment is not philosophically compelling, Burge, who is not even a dualist, dismisses it outright. A more serious issue with mental causation is a potentially inconsistent interference with physical causation which is subject to natural law. For materialism mental is a manifestation of physical, so mental causation reflects physical causation, but this does not clearly resolve the issue unless mental is also epiphenomenal, i.e. translatable into impersonal terms where mental reasons and impulses play no role. That is a problem because it seems to reduce man to machine, not to mention free will issues. Burge explicitly advocates an agnostic middle path, where we acknowledge phenomenological uses of the mental, but withhold judgement on its ontological nature and interaction with the physical until further investigation:

"Why should mental causes of physical effects interfere with the physical system if they do not consist in physical processes? Thinking that they must surely depends heavily on thinking of mental causes on a physical model... But whether the physical model of mental causation is appropriate is part of what is at issue".

This is less explicitly embraced by other non-reductivists, see e.g. 1950-2000 historical survey in Burge's Foundations of Mind (Ch.20).

Among those who dare step into the physical models most prominent, predictably, are not professional philosophers but philosophizing physicists. The strategy is known since Boussinesq pioneered it in 1870s. Find "causal gaps" in laws of nature and describe how mental provides a "guiding principle" to resolve the indeterminacy, while respecting the conservation laws, or emerges from one. Boussinesq made do with non-uniqueness in (non-Lipschitz) classical models, but since Heisenberg quantum mechanics is used instead. The idea is that "consciousness causes collapse", and the task is to find a mechanism that obviates Tegmark's objections to "quantum mind" wrapped into his metaphor that brain is "too warm, wet, and noisy". Penrose made an extravagant but empirically testable suggestion involving quantum gravity and microtubules. More recently a theory in this vein appears in Kauffman's Physics and Five Problems in the Philosophy of Mind, who relies in particular on a recent discovery of the role of quantum effects in photosynthesis, which seems like an exception to Tegmark's "too warm, wet, and noisy".

  • The QM effects in photosynthesis are not, in hindsight, all that shocking due to the highly organized electronic structure of the photosynthetic reaction complex. (Indeed, the phenomenon helps answer the question "why so many chlorophyll?": because they make an awesome light-gathering antenna with quantum enhancement!) The physical principles that may allow it to work are of the sort already well-known: spatially localized, very fast, etc.. It isn't terribly relevant to the "warm, wet, and noisy" objection because the PRC isn't all that warm, wet, or noisy on the relevant timescale!
    – Rex Kerr
    Commented Oct 23, 2015 at 1:22
  • Not realy sure about this: "Neuroscience or physiology at this point have precious little to say on what it is, how it comes to be, or even what the physical correlates of qualia"
    – borjab
    Commented Oct 24, 2015 at 12:17
  • 'There is a sentimental aversion to letting the mental act causally on the physical': who by? Commented Oct 24, 2015 at 21:22
  • @borjab I changed the phrasing. There were some major advances in detailing some mental processes and mapping them onto the brain, especially in visual perception, see Crick's Astonishing Hypothesis. But Crick advocates focusing on such specific aspects, how instead of why, and looking for narrow empirically testable hypotheses about mind/brain relation. He says that at the time of the writing (1995) few neuroscientists and physiologists were pursuing even such limited programme.
    – Conifold
    Commented Oct 28, 2015 at 1:41
  • @Mozibur Ullah Burge traces it back to Descartes:"There is a vague sense abroad that alternatives amount to superstition. One common idea is that there is some intrinsic mystery in seeing mental events, imagined as nonphysical, as interacting with physical events. Descartes thought this too; and perhaps there was some plausibility to it, given his conceptions of mental and physical substance". He also blames the dominance of materialism in American philosophy post 1960 on it, see p.445 in ruccs.rutgers.edu/faculty/pylyshyn/Burge_OriginsOfObjectivity/…
    – Conifold
    Commented Oct 28, 2015 at 2:20

According to my observation it is rather seldom that dualists actually explain the interaction of the mind and body. Often they restrict themselves to criticizing the monist position, hereby calling on our introspection: We experience that we can trigger our actions on the basis of rational decisions.

There is one well-known exception from the 20th century: John Eccles -- a famous physiologist. In his later years he worked on a theory that the mind controls the body in a certain part of the brain ("liaison brain") by using certain quantum effects. That theory has never been developed to a state of testability, nor has it been accepted by the majority of neuroscientists, despite Eccles' fame.

Also Roger Penrose has published his thoughts about a theory to explain mental causation on a scientific basis.

  • Didn't Penrose also use Quantum effects? I recall him using this in "Shadows of the Mind" but that was to explain consciousness, although it's been years since I read the book.
    – R. Barzell
    Commented Oct 20, 2015 at 15:53
  • Penrose falls into the "God of the Gaps" realm, mixing potential and necessary too freely. So I am not sure all this notion that 'will' abides in some quantum magic should not just be taken as the wishful thinking of reluctant idealists.
    – user9166
    Commented Oct 20, 2015 at 17:34
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    Actually, this is all physicalism, all the way down, and not an answer of any kind. QM explanations like this, if validated, would become, for physicalists, theories of "how the brain actually makes decisions" and just lose reference to the mind entirely. It is only their unresolved status, and thus basic irrelevance, that makes them potentially about the mind. Since we have redefined physical to accommodate QM, there is no answer that can't be consumed by monism and relabeled.
    – user9166
    Commented Oct 20, 2015 at 18:26
  • @R. Barzell You are right. Penrose employs quantum effects to approach the problem of mental causation, cf. Chapter 7 Quantum theory and the brain of Penrose, Roger: Shadows of the Mind. 1994. But I am not able to judge the weight of his arguments and to disentangle the role of consciousness for mental causation.
    – Jo Wehler
    Commented Oct 20, 2015 at 21:20
  • Having dabbled in quantum computing in grad school, I find the whole brain as a QC pretty far fetched, it is indeed too hot to be one and so far nobody has proven that QTMs can do anything that regular TMs can't pull off. On more general note, throwing QM into the mix always felt to me like the modern version of DesCartes pineal gland: Let's take something we don't completely understand yet and invoke it to solve all of our mind-body problems. Commented Oct 26, 2015 at 4:42

You ask about dualism, and then list as 'modern dualists' folks who are really idealists but that admit some aspect of 'property dualism' may or may not be true. Kripke's property dualism, and its weaker form in Nagel and Searle does not admit independence of the mind from the body. So the issue of how mind affects body does not arise.

Given that this seems to be your choice of vocabulary, whether or not it is proper in the estimation of the people being discussed, I will go ahead and answer from the idealist position, which it seems you wish to include in the dualist realm in order to have 'monism' really mean physicalism or its evolving equivalent.

Throwing it back that far, you don't need to get very modern to have and solve this problem, and no new science actually bears on the classical solutions that are actually any good.

From a layered idealist position like that of Kant, or Leibniz (Kripke or Searle or Nagel) the mind and the body are different aspects or interpretations of the same thing. It is easiest to see how the mind 'causes' the body, and everything else. It is possible the reverse is also true, but one does not need two answers for one question. The ontological difference is one of complete dependence, in one being more basic than the other, or in the two being the same thing measured in different ways, and not an independence.

At base nouminal nature causes phenomenal action. Or the 'Moot of all particles' adjusts its mutual observations, and in aggregate of the competing wills, we see physical motion. Or some other intersubjective interaction causes a compromise between the effects of a complex mind. The lack of the direct effectiveness of most direct will is caused by the fact of the lack of coordination of the will that drives it.

The notion is like the modern mathematical notion of duality -- the same thing presenting itself in two different forms -- than a Cartesian dualism -- the actual existence of two independent realms.


This big problem sprawls all over the place. In one sense, if we are meaningfully relating ideas about "mind" and "body" then we have already "homogenized" them into some sort of idealist monism. Obviously, they are being related "in some mental medium."

Can these ideas then be reduced back into "matter" and material "causality"? Here, we find ourselves dealing with an ever more problematic and, more to the point, probabilistic definition of "matter," one that even "stone cold physics" can no longer rid of the "observer," that free or indeterminate entity who subsists now as a kind of infinite regress.

One recent experiment in cognitive science, can't recall the name, suggest that neurons actually "act" prior to what appears to be a "reaction." Almost as if they go "faster" than the material, causal world bounded by the speed of light. Seems both intriguing and a little fishy.

I don't know about the names you cite as "dualists." I don't quite get the Chinese rooms and bats in a basically Darwinian ontology. I might suggest that they are "monists" who see some fallacy of self-reference in a physics that explains all physicists. No matter how big the explanatory box gets, there must always remain technically immeasurable sources of "origination" external to it.

Thus we accept, as we do our "zero" and "infinity" workarounds, a QM indeterminacy or Kantian transcendental or some other "unknowable" in which our apparent agency resides in a state of chaotic micro-choosing, prior to any knowable "choices."

Sorry, I sort of barged along without really answering your question. But I'm not sure that the many arguments opposing a materialist reduction of mind entail a true Cartesian dualism, just a Lockean "I know not what."

  • Neurons acting before reacting is probably like Bacon deciding that fire finds naphtha at a distance, and not like Newton deciding gravity acts on matter at a distance. Enough of the data is there to start preparing in case a reaction is necessary, and there is nothing time-reversed at all, just cells laying bets on the future given unclear hints as to what might be demanded of them. People forget that chemical transfers are mostly continuous and not discrete events.
    – user9166
    Commented Oct 20, 2015 at 20:57
  • Yes, I didn't put much stock in that "finding." But I am interested in descriptions of Platonic anamnesis, Bergsonian duration, and what might be called some kind of electromagnetic "time reversal" in thinking. Not that I have anything more than a suspicion of "something there." Time and "re-membering" are curious things, more so at the micro-scale. I've yet to see the description that made me say, Aha! Commented Oct 20, 2015 at 21:44
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    My leaning in that direction is the Boltzmann notion that time flows both ways, but entropic pressure keeps it mostly unidirectional, also captured in the "Brownian motion of time" from places like journals.aps.org/pr/abstract/10.1103/PhysRev.138.B1332 I am not against the notion time reverses, but the 'penumbra' of time is more likely to capture most edge cases -- we think things happen, but in reality they fade into existence, happen and fade out, because most of the media are continuous in some way.
    – user9166
    Commented Oct 20, 2015 at 23:24

David Chalmers, who splits his time between being a property dualist and a panpsychist, addresses this problem in The Conscious Mind, in chapter 5 - The Paradox of Phenomenal Judgment

For him the paradox manifests in the fact that we are cognitively aware of conscious experience - for example, talking about qualia seems to be one of its causal effects:

We know about our experiences, and make judgments about them; as I write this, a great deal of my thought is being devoted to consciousness.

But he remains unsatisfied with the explanations he explores in that chapter.

In the book he also presents a position he calls non-reductive functionalism, according to which, conscious experience is an invariant of functional organization, and if you follow his arguments down the rabbit hole it seems that their consequence might be that qualia is in some way identical with causality itself.

While describing himself as a dualist, Chalmers nevertheless believes that a Turing machine running the right "program" will have qualia, and since Turing machines are deterministic, I think that the only way to dodge epiphenomenalism at that point is to note that the only place a non-epiphenomenal qualia may hide in a physically implemented mechanical Turing machine is, strangely enough, causality itself (whatever that could possibly mean).

[A shameless plug warning] However, while I find that kind of speculation attractive, I believe the thought experiments he employs to argue for the principle of organizational invariance are not convincing - and I argue for it in Yet Another Objection to Fading and Dancing Qualia.

  • 'Qualia is identical with causality' seems like it's been lifted or adapted from Hume. Commented Oct 24, 2015 at 21:12
  • I could have lifted it somewhere, maybe Hume, maybe even Chalmers writes it somewhere, but unfortunately my memory will not betray the source, so some vain part of me secretly credits itself with that mysterious combination of words; can you expand on where and in what way, Hume can be seen as suggesting such a thing?
    – nir
    Commented Oct 24, 2015 at 21:17
  • Actually from your sentence I assumed it was Chalmers ;-). More broadly it comes from Descarte as time as inner sense, then for Hume it's not just time but also causality, but I think he talks about bundles of sensations ie qualia. Commented Oct 24, 2015 at 21:29
  • So putting those together there is an anticipation or echo of said sentence. Commented Oct 24, 2015 at 21:30
  • Can you provide a reference to the relevant passage?
    – nir
    Commented Oct 24, 2015 at 21:31

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