I am trying to work out if there is a middle ground theory between substance and property dualism?

Substance dualism:

  • physical and mental domains are fundamentally different and separate substances or entities.
  • Mental states, such as thoughts and feelings, cannot be reduced and fully explained by physical processes in the brain.
  • Mental states (soul) continues after body dies

Property dualism:

  • mental properties are emergent properties of physical systems.
  • mental properties can be partially reduced to physical properties
  • mental state (soul) ceases to exist

Is there a middle ground that says

  • physical and mental domains are separate but intertwined substances or entities.
  • Mental states, such as thoughts and feelings, can be reduced, at least partially to physical properties
  • Mental states (soul) continues after body dies
  • 1
    It is unclear how "separate but intertwined" is different from substance dualism. In the classical Cartesian dualism physical and mental causally interact with each other, see interactionism, and it is hard to see how any kind of dualism can get by without its sides "intertwining" somehow. There is also old school hylomorphism, where form ("mental") and matter ("physical") are always linked, but "substantial forms" like souls can be transferred to a different carrier, e.g. after death.
    – Conifold
    May 3, 2023 at 2:50
  • You might havta work on the metaphysical implications of yer madhyaloka. Jun 3, 2023 at 6:12

3 Answers 3


There are many middle grounds.

First, most substance dualists do not even hold by the complete irreducibility principle -- as most substance dualists consider mind to be generative of matter (that is the essence of divine creation -- mind generates matter).

Stepping from absolute difference substance dualism toward property dualism, I am a substance dualist who does not hold that logic categories are absolute, but are pragmatic descriptions of consistencies. Hence matter and mind are clearly different in practice, but might have some fundamental similarity that could manifest under some circumstances.

Also, not all substance dualists hold that mind survives death. Taoist and Navajo spiritual dualism thinking holds that mind/self is created by an emergence process when several different types of spirit fuse together, and they fall back apart, leading to the ending of that mind upon death.

Karl Poppers emergent dualism held that consciousness IS a "substance" (world 2) that is emergent from matter, and is causally independent of it. Popper considered minds to die when the body they emerged from die, but some emergent substance dualist thinking holds that emergent phenomenon, including minds, can survive the loss of their original substrate.

The OP found this concept most interesting, so I will add two references for Popper's emergent dualism. The most comprehensive is The Self and Its Brain, a mammoth book written collaboratively with a Nobel prize winning neurologist, John Eccles. A briefer summary, which focusses more on the three worlds triplism that Popper adapted from Frege, is found here: https://m.moam.info/three-worlds-the-tanner-lectures-on-human-values-pdf_647a088f098a9e8f5f8b45d3.html?utm_source=slidelegend

Emergent substance physicalism need not treat mind as a "property" and could treat it as a substance. The main thing that distinguishes emergent substance physicalism from emergent dualism is whether mind can be independently causal on matter. Emergent substance physicalism does assume physical death ends consciousness.

Now, I started this list at one of your options, then walked toward the other. One could also look beyond those options further in the direction of dualism by considering variants of idealism. One can look at idealisms that treat matter as mostly stubborn, thru idealisms that treat mind as strongly powerful in modifying matter.

One can also go off this spectrum, and consider variants of neutral monism, that accept differences between mind and matter, but assume they are both reflections of some other realer underlying substance.

  • many thanks for such a detailed response. If I understand correctly there are a few options I could possibly explore, but of those put forward emergent substance dualist might be the closest to fulfilling the criteria I put forward
    – Teddy
    May 2, 2023 at 20:19
  • @Teddy -- Yes. Karl Popper argued for the best model of this that I have seen in The Self and Its Brain, but without your post death survival.
    – Dcleve
    May 2, 2023 at 20:35
  • the post death survival may not be essential for my requirements as I was using the mind-body phenomenon to explain what I was looking for. I am actually trying to consider the application of dualism to another phenomenon, namely the relationship between our real self and digital self we put forward on the Internet. What I am pondering seemed to parallel with dualism, so I was trying to understand the different versions to see which might be most applicable.
    – Teddy
    May 2, 2023 at 20:45

Yes, in Orchestrated Objective Reduction (Orch OR) thoughts may be linked to, or partially are, non-local phenomena.

In Hameroff's explanation of out-of-body experiences under anaesthesia he liked the brain to a radio receiver of cosmic field 'thoughts'; the anaesthetic loosened the localisation of consciousness.

If thoughts or "mental states" are to some extent cosmic field phenomena then this is the OP's excluded middle.


Suppose that we start out with the pair of concepts substance and property so that we can generically say things like:

  1. X is a substance.
  2. X is a property.
  3. X is both a substance and a property.
  4. X is neither a substance nor a property.

An intermediary between, or supersession of, substance- and property-dualism might be cashed out in terms of (3) or (4), then. However, we should also be inclined to consider variations on the concept of substance or on the concept of properties. In bundle theories of object-talk, for example, the concept of a substance to which properties adhere/attach is replaced by the concept of a set of properties, where the principle for identifying which elements are in such a set (and hence which characterize separate objects when we have separate sets) is not substance-theoretic. Perhaps, then, one might identify a mind/matter dualism where mind is somehow equated with a principle of bundling, perhaps as a "meta-property" of the properties in some bundles. (I am generally sure that there are essays out there in which such proposals are explored, but I don't have any specific knowledge of such essays.)

Another relevant ambiguation over property theory could involve Zalta's distinction between encoding and exemplifying properties. Normal (property) dualism could be taken as the claim that there can be mental properties which are exemplified by non-mental particulars. But one might try imagining that mental properties are never exemplified by non-mental particulars but are possibly encoded by/in them (or that mental properties are sometimes non-mentally exemplary and sometimes non-mentally encoded, etc.).

Then one could go on to imagine theories where mental substances either only exemplify or only encode mental properties, or where mental substances can satisfy both property relations, where there are mental properties exemplifiable by mental substances and encoded by non-mental ones, and so on and on.

With respect to the OP subquestion "mental states continuing after death": so then suppose that we are physical substances which can variously encode and exemplify mental properties. Lindsky and Zalta pose the question of contingently abstract objects and there are alternatives to property theory, known as trope theories, which involve a question of abstract particulars. So we could imagine that there are contingently abstract mental particulars, such that relative to a physically living person these particulars are concrete, but so that relative to such a person after death (as well as before life), these particulars are abstract.

Such an account is (roughly) similar to the Catholic doctrine of souls as "forms" of human bodies, where "forms of" is read in an Aristotelian manner. (C.f. the concept of haecceities, which might be thought to exist necessarily such that, albeit indexed to exact particulars, their existence is independent on the occurrent existence of those particulars. One philosophically self-aware fiction writer nowadays, Brandon Sanderson, appears to define something specter- or spirit-like about physical beings in such terms.)

ADDENDUM: Modality-theoretic options

At a squiggly diagonal off from the above-mentioned haecceity-talk, there is a debate in the theory of modality between actualists and possibilists, which is roughly a debate over the existence of "mere possibilia" (things that are possible simpliciter, rather than possible only in relation to actualities). So one might imagine a dualism such that actual substances are strictly physical whereas mental substances are strictly merely possible when further mental properties are not physically instantiated (as actualities), etc.

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