Some arguments for substance dualism, and one objection

Philosophy of mind is not something I’ve studied very much, but I do know about the different views like physicalism, epiphenomenalism, property dualism and substance dualism. I also know some of the basic arguments for and against each view.

In this post, I just wanted to show people a little bit about how you argue for substance dualism, using philosophical and scientific arguments. I find this topic to be really really dry, and I can barely stay awake when J.P. Moreland talks about it in lectures. But I hope a little bit of exposure won’t put you all to sleep.

Philosophical arguments

Let’s start with this old paper by John Depoe.

He writes about the persistent identity argument:

Another argument supporting substance dualism is that one maintains personal identity through change. Even though one is continuously going through physical changes and experiencing different mental states, a person continues to be the same person. If persons were identical with their physical parts or mental states, they would cease to be the same persons as these changes occurred. Therefore, it is necessary to postulate an immaterial, substantial self that endures through change.

Suppose that someone believes that people do not maintain identity through change and concludes that the previous argument for substance dualism fails. This denial of personal identity through change, I contend, presents untenable difficulties. First, there is one’s own awareness of being the same person through change. Moreover, if one is not literally the same person through these changes, how can a person maintain long-term goals and desires?

If you are your body, and your body is always changing, then you aren’t the same person now as 5 minutes ago.

There are more arguments for substance dualism here, from J.P. Moreland.

Experimental evidence

Doug Groothuis talks about some experimental evidence in this paper.


Dr. Wilder Penfield was known for his ground-breaking work with epilepsy. His work involved stimulating brain tissue in conscious patients in order to find the causes of epilepsy. During these sessions Penfield found that the prodding of certain areas of the brain triggered vivid memories of past events. The patients reported remembering clearly such things as the taste of coffee. One patient, while on an operating table in Montreal, Canada, remembered laughing with cousins on a farm in South Africa. What amazed Penfield was that his patients, who were not under anesthetic, were simultaneously conscious of the re-experienced memories and of being prodded by an electrode in an operating room. Penfield called this a “double consciousness” wherein a memory was stimulated physically but was attended to and recognized as a memory by a conscious patient. Penfield likened this to the patient watching a television program while remaining aware that it wasn’t now happening.

Penfield repeated these results on hundreds of epileptic patients and concluded that a separable mind was able to track what the brain was doing as a result of the artificial stimulation. One’s mind in a sense could transcend the operations of the brain, monitoring memories without actually placing oneself in the situation remembered. Penfield noted that “The mind of the patient was as independent of the reflex action as was the mind of the surgeon who listened and strove to understand. Thus, my argument favours independence of mind-action.” Penfield also stated that if we liken the brain to a computer, it is not that we are a computer, but that we have a computer.

Penfield, who began his research as a materialist, switched to dualism after extensive research with epileptic patients. He said, “Something else finds its dwelling place between the sensory complex and the motor mechanism. . . . There is a switchboard operator as well as a switchboard.”

Although nonepileptic patients do not respond similarly to brain stimulation, other researchers, such as Sir John Eccles, a neurobiologist, have similarly concluded that the brain alone cannot account for a many phenomena. Eccles’ hypothesis is that the self-conscious mind is an independent entity that is actively engaged in reading from the multitude of active centres in the modules of the liaison areas of the dominant cerebral hemisphere. The self-conscious mind selects from these centres in accord with its attention and its interests and integrates its selection to give unity of conscious experience from moment to moment.

Thus, Eccles’ conclusions agree with Penfield’s, and his areas of research extend farther than that of epileptic patients. Eccles deems the “monist materialist” hope for an eventual physical explanation for mental events as wrongheaded in principle because mental events are not “simply derivative of aspects of nerve endings. There is no evidence for this whatever.” Further, Eccles argues that his “strong dualist-interactionist hypothesis . . . has the recommendation of its great explanatory power. It gives in principle at least explanations of the whole range of problems relating to brain-mind interaction.”Eccles notes that it has been impossible to develop a materialist explanation of “how a diversity of brain events come to be synthesized so that there is a unified conscious experience of a global or gestalt character.” Given this impasse, Eccles proposed that “the self-conscious mind” serve to integrate the apparently disparate brain processes into a unified consciousness.

I think that Alvin Plantinga, Keith Yandell, J.P. Moreland, William Lane Craig, Stephen Davis, John Depoe, Douglas Groothuis and Charles Taliaferro all defend substance dualism. I’m a substance dualist, myself.

What’s the objection to substance dualism?

The big objection to substance-dualism is the problem of how you get the non-physical substance to interact with the physical substance. It’s like how people put forward the grounding objection when talking about middle knowledge and where God’s knowledge of counterfactuals of creaturely freedom comes from. I wonder if anyone can post a comment for me to point me to a resource on answering the interaction problem in the comments.

UPDATE: One of my elite special forces ninja commenters writes:

Here’s Ed Feser on the Interaction Problem:


The thrust of his argument is that, if the soul is the extension of the body’s “form” without matter, then it interacts with the more material parts of us in the same way that forms in general interact with matter- this approach involves rethinking our metaphysical understanding of matter, rather than coming up with a clever idea of the soul, and it does get rather involved in Thomistic metaphysics, but I think it’s pretty interesting.

10 thoughts on “Some arguments for substance dualism, and one objection”

  1. Here’s Ed Feser on the Interaction Problem:


    The thrust of his argument is that, if the soul is the extension of the body’s “form” without matter, then it interacts with the more material parts of us in the same way that forms in general interact with matter- this approach involves rethinking our metaphysical understanding of matter, rather than coming up with a clever idea of the soul, and it does get rather involved in Thomistic metaphysics, but I think it’s pretty interesting.


  2. It’s hard to prove, but It’s something we observe, so maybe like in the case for the existence of the universe, the burden of proof should lie on those that disagree with substance-dualism.

    As an athlete it was very important for me and still is to be able to mentally control physical reactions. Whether it’s calming nerves before a race or going through a difficult work-out, the reality of the effects of psychosomatic effort is obvious.

    My parents use their minds to get rid of warts. I’ve tried to, but I’m not as mentally tough as they are.

    You can stop blood flow, you can increase oxygen to your muscles, many bodily functions can change instantly depending on your mental state.

    Understanding middle knowledge is still a harder concept to grasp than this. Why wouldn’t we assume that when a God that created us in his image, breathed life into us, that what we describe as our life, involves the ‘us’ and then the ‘life’ part. The temporal and the eternal. The whole universe runs on those properties. The smaller and closer Eternal things come to us the easier they are to perceive. So middle knowledge, God’s influence in creation, these are difficult concepts to grasp, but psychosoma? I hope we can at least accept it as a reality even if we want to pretend it’s very complicated to understand.


  3. Here’s a chapter that I wrote on the subject once that may help point out some other key arguments physicalists use: They’re concerns definitely go beyond the interaction problem, though that’s a key one.

    And, the problem with the Thomistic response is that it’s not going to convince anyone who isn’t already a Thomist (which eliminates pretty much everyone you’d want to convince). In my experience, most dualists ultimately end with some kind of appeal to mystery (i.e. the soul is a different substance and therefore its causal interactions are simply different from physical causation). And, they’ll strengthen this by pointing out that physical causation has its own problems and ambiguities. So, if physicalists can’t offer a compelling explanation of causation, why should they expect dualists to be able to do so?


  4. See ch. 4 of Soul Hypothesis: Investigations Into the Existence of the Soul for a response to supposed scientific problems surrounding the interaction problem.


  5. I haven’t researched philosophy of the mind too much either, though I do know some of the objections to dualism such as neural darwinism. The argument is also called neural group selection and it has three parts (I copied the parts from wikipedia)

    Anatomical connectivity in the brain occurs via selective mechanochemical events that take place epigenetically during development. This creates a diverse primary repertoire by differential reproduction.

    Once structural diversity is established anatomically, a second selective process occurs during postnatal behavioral experience through epigenetic modifications in the strength of synaptic connections between neuronal groups. This creates a diverse secondary repertoire by differential amplification.

    Reentrant signaling between neuronal groups allows for spatiotemporal continuity in response to real-world interactions.

    It’s a little bit confusing. Anyway, I recently bought a college philsophy book. I really like the format! The book is layed out in sections and instead of the authors describing the philosopher’s work, each chapter has excerpts from books such as Aquinas’ summa theologica to Daniel Dennet’s Consciousness Explained book. Looking in the book, I found Dennett’s objection to dualism.

    “A fundamental principle of physics is that any change in the trajectory of any physical entity is an acceleration requiring the expenditure of energy, and where is this energy to come from? It is this principle of the conservation of energy that accounts for the physical impossibility of “perpetual motion machines,” and the same principle is apparently violated by dualism. This confrontation between quite standard physics and dualism has been endlessly discussed since Descartes’s own day, and is widely regarded as the inescapable and fatal flaw of dualism” (Consciousness Explained, p. 35)”


    1. This so-called “Fatal Flaw” actually seems resolvable from my perspective.
      Let’s start with a rhetorical response: “Computer programs can cause changes in physical systems, despite the fact that they are not physical. Where does the energy to cause these changes come from? This is a fatal and inescapable flaw to computer science. Therefore, computer programs are just an urban legend.”
      This is transparently absurd! The computer supplies the energy to carry out these changes, the software simply tells the computer how to use that energy. The same is true in mind-body Dualism. If the answer isn’t obvious in this modern world, where we have a decent analogy, what on Earth are we coming to?

      I agree that the question of how the mind and body interact is a problem, and I’ve been trying to resolve that. I have established a number of criteria that I must satisfy in any possible solution:
      1) The mind and body must function together as a unit. (Why? The ancient Semites (Hebrews) believed in a type of Holism, and Christianity has a thorough ground in Judaism. This does not require that the two are inseparable, however.)
      2) It must shed light on why humans can’t program computers by the mere thought. (Why? If the mind can interact with the body, but not other things, it follows there is an explanation.)
      3) The fact that drugs can alter the mind must be explained. (Interestingly, we can actually destroy a large portion of the brain’s “Non-eloquent regions” without any significant effect, and many patients (ref. Dr. Michael Egnor) actually come in with these kinds of injuries, or else leave with them!)
      4) The six largest pieces of evidence for dualism must be explained in an elegant fashion. (Why? Just because we explained these phenomena is not enough; a convoluted model can be proposed within materialism, but that would just demonstrate the inadequacy of materialism.)
      5) Freewill must be Libertarian, not Compatibilist. (Why? In Compatibilism, the person is predetermined, but they are part of the causal chain. This is not true freedom, as you are still predetermined. Forget the rebuttal that “Telling somebody what they are predetermined to do alters the future;” it doesn’t, as You were predetermined to tell them. Therefore, you were predetermined to alter the future. Therefore, the future has not been altered, QED. A limit in knowledge is not a refutation of this simple fact, another proof that our world is not as intelligent as we like to believe.)


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