Conversatio Divina

Part 2 of 2

The Substance of Consciousness

A Comprehensive Defense of Contemporary Substance Dualism

Brandon Rickabaugh & J. P. Moreland

01.  Substance Dualism in the 21st Century


1.1.1 The Great Revolt Against Dualism

At the end of the 19th century, substance dualism—roughly, the thesis that the human person is comprised of a substantial immaterial soul and a physical body—was widespread. Materialism was not a live option. As U.T. Place observed,

[Ever] since the debate between Hobbes and Descartes ended in apparent victory for the latter, it was taken more or less for granted that whatever answer to the mind-body problem is true, materialism must be false. Place, U. T. (2002). A pilgrim’s progress? From mystical experience to biological consciousness. Journal of Consciousness Studies, 9, 36. As quoted in Kind, A. (2019). The mind-body problem in 20th century philosophy. In A. Kind (Ed.), Philosophy of mind in the twentieth and twenty-first centuries: A history of the philosophy of mind (Vol. 6, p. 73). New York, NY: Routledge.

This sociological fact changed quickly, bringing about what William James described as “the evaporation of the definite soul-substance.” James, W. (1904). Does “consciousness” exist? The Journal of Philosophy, Psychology and Scientific Methods, 1, 478. Arthur O. Lovejoy deemed the 20th century as “the Age of the Great Revolt against Dualism.” Lovejoy, A. O. (1930). The revolt against dualism: An inquiry concerning the existence of ideas (p. 1). La Salle, IL: Open Court Publishing. The inevitable defeat of substance dualism was assumed to be a foregone conclusion. Gilbert Ryle had, in the words of Daniel Dennett, “danced quite a jig on the corpse of Cartesian dualism.” Dennett, D. (1987). The intentional stance (p. 214). Cambridge, MA: MIT Press. Dennett is referring to the arguments in Ryle’s 1949 book, The Concept of Mind.

Rebellious defenders of substance dualism remained (e.g., C. J. Ducasse (1881–1969), William McDougall (1871–1938), G. F. Stout (1860–1944), Karl Popper (1902–1994), John Eccles (1903–1997)). Physicalist William Lyon goes so far as to announce

… there is no doubt at all, that by the last decades of the nineteenth century and during the first [three] decades of the twentieth century, the new scientific psychologist’s view of the correct way of finding out about minds, and implicitly of the nature of minds, was deeply Cartesian.Lyons, W. (2001). Matters of the mind (p. 14). New York: Routledge; cf. 1–36, especially 13–24. Brackets ours

Yet, despite a remarkable rise in apt defenders in the latter 20th century, novel and sophisticated defenses of substance dualism were largely ignored. In the words of D. M. Armstrong, dualism was seen as “curiously formal and empty.”Armstrong, D. M. (1968). A materialist theory of mind (p. 23). London: Routledge and Kegan Paul. Daniel Dennett incites the overall acceptance of “the dogmatic rule that dualism is to be avoided at all costs.” Dennett, D. (1991). Consciousness explained (p. 37). Boston, MA: Little, Brown and Co.; his italics.

Denunciations of substance dualism are often expressed quite dramatically. Here is a representative sample:

“Few ideas are as unsupported, ridiculous and even downright harmful as that of the ‘human soul’.”Barash, D. P. (2023). Stuck with the soul. Aeon Essays. (March 20, 2023). Retrieved from

… dualism is akin to explaining lightning in terms of Thor’s anger, and hence is fundamentally primitive and pre-scientific. Braddon-Mitchel, D., & Jackson, F. (1996). Philosophy of mind and cognition (p. 8). Oxford: Blackwell.

… the concept of a non-physical soul looks increasingly like an outdated theoretical curiosity.Churchland, P. (2002). Brain wise: Studies in neurophilosophy (p. 173). Cambridge, MA: MIT Press

To defend dualism is to close one’s eyes to the enormous and ongoing scientific developments in the mind and brain sciences in the past few centuries—and to wallow in mystery. Schouten, M. K. (2001). Theism, dualism, and the scientific image of humanity. Zygon, 36(4): 696.

“Immaterial mind” or “soul,” like “élan vital,” “elf,” or “chupacabras,” are ghostly expressions that come from mistaken frameworks or conceptions and do not refer to anything. Sabatés, M. H. (2005). Reductionism in the philosophy of mind. Encyclopedia of Philosophy. Retrieved from

There is no spirit-driven life force, no throbbing, heaving, pullulating, protoplasmic, mystic jelly. Life is just bytes and bytes and bytes of digital information. Dawkins, R. (1995). River out of Eden: A Darwinian view of life (p. 18). New York, NY: Basic Books.

Notice that these quotations employ mere rhetorical devices. John Searle has pointed out at least four rhetorical devices used in the philosophy of mind to either ridicule opposing views or hide the implausibility of one’s view.Searle, J. Rediscovery of the mind (p. 9). Boston, MA: MIT Press Searle’s observations apply equally to so many dismissals of substance dualism.

  1. The use of technical jargon to cover up the implausibility of one’s view.Ibid., 9.
  2. The stylistic use of prose to evade clearly stating one’s argument.Ibid., 4.
  3. Naming an opposing view (e.g., “the Cartesian intuition”), to which one then denies by name and not by content.Ibid., 4–5.
  4. The covering up of one’s troubling view by means of an analogy with a scientific discovery of the past that also seemed silly or ignorant.Ibid., 5.

To Searle’s list, we add a fifth device.

5.  The practice of associating substance (and, sometimes, property) dualists with accepting the existence of spooks or spooky stuff, ghosts, or other paranormal entities is best left to the pages of The National Enquirer. These labels function as a way of associating dualism with astrology, the occult, or other superstitious views contrasting with physicalism, which is the clear implication of tough-minded progress in the hard sciences. In addition to Gilbert Ryle’s (infamous) statement about “the ghost in the machine,” see Kim, J. (2018). Against cartesian dualism. In J. J. Loose, A. J. L. Menuge, & J. P. Moreland (Eds.), The Blackwell companion to substance dualism (pp. 154–167). Oxford: Wiley-Blackwell. The quote is on 153; Churchland, P. (2013). Matter, and consciousness (3rd revised ed., pp. 12–16). Cambridge, MA: MIT Press; Murphy, N. (2007). Reductionism: How did we fall into it and can we emerge from it? In N. Murphy & W. R. Stoeger (Eds.), Evolution and emergence (pp. 19–39). Oxford: Oxford University Press; Steward, H. (2012). A metaphysics for freedom (p. 228). Oxford: Oxford University Press.

One would hope that such unabashed ridicule would reflect the great strength of antidualist arguments. But, as we will demonstrate in the chapters to come, that hope is questionable if not outright ungrounded.


1.1.2 The Resurgence of Substance Dualism

Fast forward to the late 20th and early 21st centuries. Things are changing. We are witnessing a resurgence of substance dualism. Physicalism remains the dominant view in the philosophy of mind. Yet, it is no exaggeration to say that substance dualism is undergoing an unforeseen revival and is poised to make a strong return in the 21st century. These reasons are not mere sociological reflections but expressions of the rapid growth in sophisticated new work on substance dualism. A large number of recently published book-length defenses of substance dualism evidence this, along with collections of new pro-substance dualism papers. The number of journal articles defending substance dualism is too long to list.An exhaustive bibliography is available at Conspicuous by their absence are substantive engagements with these works.



1.2.1 Admissions to the Weakness of Standard Objections to Substance Dualism

In addition to the resurgence of substance dualism, some non-dualists argue that standard objections to substance dualism are less triumphant than previously thought. After working through standard arguments against substance dualism, José Gusmão Rodrigues, himself a Russellian monist, concludes,

A significant part of current literature on the mind-body problem, personal identity and other general metaphysical questions seems to me rife with anti-dualistic assumptions without good arguments to back it [sic] up. Such an attitude is dogmatic and contrary to good philosophical spirit.Rodrigues, J. G. (2014). There are no good objections to substance dualism. Philosophy, 89(2), 221–222.

Likewise, materialism William Lycan admits,

Being a philosopher, of course I would like to think that my stance is rational, held not just instinctively and scientistically and in the main-stream but because the arguments do indeed favor materialism over dualism. But I do not think that, though I used to. My position may be rational, broadly speaking, but not because the arguments favor it: Though the arguments for dualism do (indeed) fail, so do the arguments for materialism. And the standard objections to dualism are not very convincing; if one really manages to be a dualist in the first place, one should not be much impressed by them. Lycan, W. (2009). Giving dualism its due. Australasian Journal of Philosophy, 87(4), 551.

In Chapter 10, we will argue in detail that the standard objections to substance dualism fail in ways even staunch anti-dualists must acknowledge.


1.2.2 Admitting the Faith of Anti-Dualism

Another striking phenomenon is the growing recognition that eschewing substance dualism is essentially the expression of faith in naturalism, faith in what Karl Popper referred to as promissory materialism: that in the not-too-distant future, science will provide an in-principle explanation of all phenomena in the world, including consciousness.Cf. Popper, K. R., & Eccles, J. C. (1985). The self and its brain (pp. 96–98). New York, NY: Springer-Verlag.

David Chalmers observes, “The main residual motivation to reject substance dualism may simply lie in the term’s negative connotations.”Chalmers, D. (1996). The conscious mind (p. 170). Oxford: Oxford University Press. If Chalmers is correct, then the rejection of substance dualism is most likely driven primarily by mere ideological allegiance—by faith—rather than rigorous argument. John Searle expresses this posture well.

[We] have a terror of falling into Cartesian dualism. The bankruptcy of the Cartesian tradition and the absurdity of supposing that there are two kinds of substances or properties in the world, “mental” and “physical,” is so threatening to us and has had such a sordid history that we are reluctant to concede anything that might smack of Cartesianism.Searle, J. (1992). The rediscovery of the mind (p. 13). Cambridge, MA

As a result, substance dualism has not been tried and found wanting so much as it has been judged unacceptable and left untried.


1.2.3 Proposals of Naturalistic Substance Dualism

Indeed, the presumption of naturalism and atheism fuels most rejections of substance dualism. Why else would the guilt by religious association objection be relevant? This habit is not well thought out; some naturalists acknowledge as much. As Michael Martin, perhaps one of the leading atheists of the past 100 years, states, “atheism is not materialism … atheism is compatible with various forms of mind-body dualism.” Fernandes, P., & Martin, M. (2000). Theism vs. atheism: The internet debate (p. 19). IBD Press. Graham Oppy makes the same observation. Oppy, G. (2013). The best argument against god (p. 55). New York, NY: Palgrave Macmillan. Atheist Evan Fales observes,

A naturalist who is not sanguine about the reducibility of the mental to the physical has several options. These include token-token identity theories such as functionalism, property dualism, and—more daringly—substance dualism.Fales, E. (2007). Naturalism and physicalism. In M. Martin (Ed.), The Cambridge companion to atheism (p. 127). New York, NY: Cambridge University Press.

Naturalism, according to Fales, plausibly commits one to reject the existence of disembodied minds. But substance dualism does not entail disembodied minds, nor is naturalism incompatible with substance dualism.Ibid., 127–128 Likewise, naturalist Eric Steinhart explains,

While many naturalists dogmatically reject such mind-body dualism, progressive naturalists are open to it. They ask only for a research program which formally defines the immaterial mind and its linkage with the brain. After all, since mathematical structures need not be material, the immateriality of the mind cannot block its formal definition. Steinhart, E. (2019). Naturalism. In G. Oppy (Ed.), A companion to atheism and philosophy (p. 159). New York, NY: Wiley-Blackwell.

As examples, Steinhart refers to Ray Kurzweil and Hillary Putnam’s concession that computers are made of purely mental stuff. Steinhart cites Richards, J. W. (Ed.). (2002). Are we spiritual machines? Ray Kurzweil vs. the critiques of strong AI. Seattle, WA: Discovery Institute; Putnam, H. (1975). Philosophy and our mental life. In Mind, language, and reality. Cambridge: Cambridge University Press. While some dissenters are committed theists, nearly all naturalists and atheists reject substance dualism. However, to the surprise of many, some atheists and agnostics defend substance dualism (e.g., C. D. Broad, Karl Popper, and Michael Huemer).32 See, e.g., Broad, C. D. (1959). Autobiography. In P. A. Schilpp (Ed.), The philosophy of C.D. Broad (pp. 3–68). New York: Tudor; see 43–44; Huemer, M. (2018). Paradox lost: Logical solutions to ten puzzles of philosophy (p. 235). Switzerland: Palgrave Macmillan; and Zerin, E. (1998). Karl Popper on God: The lost interview. Skeptic, 6(2), 47–48. Still, as we will see in Chapter 2, there are good reasons to think that a naturalist should eschew substance and property dualism.



Another significant change is the recognition of intuitions against standard physicalism that have historically been used to defend property and substance dualism. Although not exhaustive, we note four.


1.3.1 The Return to the Self and Subject of Consciousness

A mark of 20th-century philosophy was the rejection of the self and attention to the subject of consciousness. Most leading philosophers of mind outright express the first. The second, if not explicit, is indeed implicit in the widespread practice of analyzing mental states without metaphysical considerations of the subject of mental states. Standard discussions of consciousness, for example, predicate phenomenal consciousness or qualia to mental states. One rarely hears of subjects—the bearers of mental states, as the thing that is conscious. Substance dualists have not followed suit but have kept the self and subject of consciousness as a necessary component of the analysis of consciousness. In Chapter 5, we argue why this must be the case for any successful analysis of consciousness. Here we note that the self and subject of consciousness are returning to the fore of consciousness studies. And resistance to taking the self and subject ontologically seriously is resisted by its obvious connection to substance dualism. Yet, the intuition of the reality of the self and subject is too difficult for many to resist.


1.3.2 The Meta-Problem of Consciousness and Cognitive Science

There is also a growing recognition that dualist intuitions that consciousness is not physical and the intuition that the subject of consciousness is an immaterial substance must be taken seriously. Once rejected as the product of ignorant folk psychology, the ubiquity and strength of pro-dualist intuitions are being recognized as essential data to be explained. The substance dualist has understood this all along. We will say more about this at the end of the next section.


1.3.3 The Revival of Aristotelianism

The growing revival of Aristotelianism during the last two decades, especially in its recognition of substances and their indispensability in solving various metaphysical problems, is a significant step away from standard physicalism and toward substance dualism. As we will see in Chapter 7, this revival has two fundamental versions—weak and strong hylomorphism.

The former reduces the substantial form (or essence) to a relational structure constituted by external relations whose relata are separable parts. This version comes perilously close to some form of vague naturalistic animalism.

But strong hylomorphism entails a more classic understanding of substances as essentially characterized particulars that, synchronically, have properties and inseparable parts as constituents and, diachronically, retain Leibnizian identity through teleological processes aimed toward an end. Here, the substantial form serves (at least) three metaphysical functions: (i) It unifies the substance synchronically; (ii) it grounds the substance’s diachronic identity; (iii) it is the teleological guide of the lawlike sequences of development for the sake of achieving its proper end.

When we talk of a revival of Aristotelianism, we refer primarily to the resurgence of strong hylomorphism in analyzing the nature of living organisms, though that revival is much broader.See Oderberg, D. (2007). Real essentialism. New York, NY: Routledge; Feser, E. (2014). Scholastic metaphysics. Heusenstamm, Germany: Editiones Scholasticae; Ellis, B. (2002). The philosophy of nature: A guide to the new essentialism. Bucks, Great Britain: Acumen Press; Lowe, E. J. (2006). The four-category ontology. Oxford: Oxford University Press; Brown, C. M. (2005). Aquinas and the ship of Theseus. London: Continuum; Simpson, W. M. R., Koons, R. C., & Nicholas, J. (Eds.). (2018). Neo-Aristotelian perspectives on contemporary science. New York, NY: Routledge. For additional resources, see Chapter 7, notes 90, 92, 101–102, and 105–112.


1.3.4 Broad Worldview Considerations

Over the last fifty years, there has been a ubiquitous resurgence of theism, predominantly Christian theism, across the philosophical disciplines. The result? Naturalism is no longer the only game in town. With the loss of its hegemony, broader worldview implications, particularly those involving naturalism versus theism, were back on the table. In the next chapter, we will apply Thomas Nagel’s recent insight that in the current setting, one must keep broad worldview issues in mind while working in philosophy of mind and conversely.

Given the ascendency of theism, proponents articulated several claims about the advances in theistic scholarship and the explanatory resources of theism vis-à-vis naturalism in the philosophy of mind, e.g., precise clarification of the intelligibility of a Spiritual Substance, additional insights on various interaction problems, the superior explanatory power of theism regarding the origin of consciousness and several features of human persons. Human persons fit naturally in a theistic worldview but remain recalcitrant for naturalism. We will take up a number of these in the chapters to follow.



Due to the persistent failures to solve the hard problem of consciousness, a growing number of philosophers are turning away from standard physicalism (a.k.a. strong physicalism). In 2005, David Chalmers compiled a list of at least 30 noted contemporary anti-physicalists. His list included Joseph Almog, Torin Alter, George Bealer, Laurence BonJour, Paul Boghossian, Tyler Burge, Tim Crane, John Foster, Brie Gertler, George Graham, W.D. Hart, Ted Honderich, Terry Horgan, Steven Horst, Jaegwon Kim, Saul Kripke, Harold Langsam, E.J. Lowe, Kirk Ludwig, Trenton Merricks, Martine Nida-Rümelin, Adam Pautz, David Pitt, Alvin Plantinga, Howard Robinson, William Robinson, Gregg Rosenberg, A.D. Smith, Richard Swinburne, and Stephen White. See Chalmers, D. (2005, September 26). Fragments of consciousness: A weblog by David Chalmers. Of course, there are materialists on this list (e.g., Trenton Merricks), but materialists about human persons needn’t be physicalists.


1.4.1 The Fundamentality of Consciousness

Among physicalist dissenters are those now positing phenomenal consciousness as a fundamental feature of reality (e.g., panpsychism and Russellian monism).See, e.g., Brüntrup, G., & Jaskolla, L. (Eds.). (2017). Panpsychism: Contemporary perspectives. Oxford: Oxford University Press; and Alter, T., & Nagasawa, Y. (Eds.). (2015). Consciousness in the physical world: Perspectives on Russellian monism. Oxford: Oxford University Press. This is significant for at least three reasons. First, as Charles Taliaferro rightly points out, the substance dualists and panpsychists both (i) recognize the irreducible reality of consciousness; (ii) resist reductive accounts of consciousness that at least implicitly result in eliminativism; and (iii) tend to reject accounts that take consciousness as both irreducible and emergent from brute matter entirely bereft of mental elements.Taliaferro, C. (2017). Dualism and panpsychism. In G. Brüntrup & L. Jaskolla (Eds.), Panpsychism: Contemporary perspectives (pp. 383–384). Oxford: Oxford University Press. Just as some have argued that property dualism leads to substance dualism,See, e.g., Lycan, W. G. (2013). Is property dualism better off than substance dualism? Philosophical Studies, 164(2), 533–542; Schneider, S. (2012). Why property dualists must reject substance physicalism. Philosophical Studies, 157(1), 61–76; Zimmerman, D. (2010). From property dualism to substance dualism. Aristotelian Society Supplementary, 84(1), 119–150; and Francescotti, R. (2001). Property dualism without substance dualism? Philosophical Papers, 30(2), 93–116.the shift toward panpsychism is likewise significant.


1.4.2 The Return of Panpsychism

Second, the shift toward panpsychism rides on certain pro-dualist intuitions. There is a growing recognition of what substance dualists have always found intuitive, that the mental is so different from the physical that consciousness is inexplicable, even ontologically disallowed, within the limitations of physicalism. Hence, a proposal more radical than physicalism is needed. In light of this, Chalmers observes,

I think that substance dualism (in its epiphenomenalist and interactionist forms) and Russellian monism (in its panpsychist and panprotopsychist forms) are the two serious contenders in the metaphysics of consciousness, at least once one has given up on standard physicalism. (I divide my own credence fairly equally between them). Chalmers, D. (2017). Panpsychism and panprotopsychism. In Brüntrup & Jaskolla (pp. 39–40).

That a leading philosopher of mind would consider substance dualism among the two serious contenders would be unthinkable in the early 20th century. And as we will argue in a moment, specific panpsychist commitments make resisting substance dualism very difficult. For an interesting argument that panpsychism can’t avoid substance dualism, see Weir, R. S. (2021). Can a post-Galilean science of consciousness avoid substance dualism? Journal of Consciousness Studies, 28(9–10), 212–228.


1.4.3 Consciousness-First Philosophy of Mind

Likewise, consider the developing consciousness-first approach to the philosophy of mind. Harold Langsam draws attention to how physicalism proceeds from commitments rejected by dualists.Langsam, H. (2001). Strategy for dualists. Metaphilosophy, 32(4), 396. Whereas physicalists privilege third-person data regarding the non-phenomenal, structural, and causal features associated with consciousness; dualists favor first-person data focused on the phenomenological qualities of consciousness.This isn’t to further the misconception that, unlike physicalists, dualists do not seek compatibility with any relevant empirical science. For an excellent criticism of this misconception, see Gertler, B. (2020). Dualism: How epistemic issues drive debates about the ontology of consciousness. In U. Kriegel (Ed.), The Oxford handbook of the philosophy of consciousness (pp. 277–300). Oxford: Oxford University Press. Given this disparity of starting points, Langsam urges the dualist to ignore the physicalist’s framing of the debate and develop a positive project showing how the dualist conception of the mind is indispensable.According to Langsam, this strategy works only for property dualism and not substance dualism, although he offers no clear reason for why we should accept this.

Thus, the consciousness-first approach rejects reductive explanations and reductive ontologies of consciousness.Adam Pautz, for example, argues that reductive accounts of consciousness cannot accommodate the various ways in which consciousness is significant (dissimilarity-grounding, reason-grounding, and thought-grounding), although non-reductive accounts of consciousness can. See Pautz, A. (2017). The significance argument for the irreducibility of consciousness. Philosophical Perspectives, 31(1), 349–407. Instead, consciousness is taken as a starting point from which to explain the nature and possibility of intentionality, mental causation, rationality, and normativity.See, e.g., Langsam, H. (2002). Consciousness, experience, and justification. Canadian Journal of Philosophy, 32(1), 1–28; Pautz, A. (2013). Does phenomenology ground mental content? In U. Kriegel (Ed.), Phenomenal intentionality: New essays (pp. 194–234). Oxford: Oxford University Press. Central to the consciousness-first approach is a commitment to the foundational role that knowledge by acquaintance plays in philosophical analysis.For recent work on the acquaintance approach to consciousness studies, see, e.g., Smithies, D. (2019). The epistemic significance of consciousness. Oxford: Oxford University Press; Gertler, B. (2012). Renewed acquaintance. In D. Smithies & D. Stoljar (Eds.), Introspection and consciousness (pp. 93–127). Oxford: Oxford University. Again, we have an example of the recent embrace of pro-dualist intuitions and methodology. Chapter 11 will chart a research program for consciousness-first substance dualism.


1.4.4 Phenomenal Transparency and the Opacity of the Physical

Third, in conjunction with rejecting standard physicalism, these pro-dualist intuitions make resisting introspective arguments for substance dualism challenging. While physicalists typically deny such knowledge, Russellian monism and Russellian panpsychism embrace the following thesis:

Phenomenal Transparency: Phenomenal concepts reveal the nature of the conscious states to which they refer.

When a subject attends to her nonconceptual acquaintance of her conscious states, she is provided with a conceptual understanding of those conscious states. Goff, P. (2017).Consciousness and fundamental reality (p. 115). Oxford: Oxford University Press. See Chapter 9 for more on this I know what pain is by attending to my direct first-person acquaintance of my experience of being in pain, in virtue of which I can form a conception of pain that is phenomenally transparent, revealing the nature of pain.

Various arguments against physicalism (e.g., the conceivability, knowledge, and explanatory-gap arguments) depend on a thesis like phenomenal transparency, according to which we have epistemic access to the nature of consciousness. Chalmers, D. (2010).The two-dimensional argument against materialism. In D. Chalmers, The character of consciousness (p. 141). Oxford: Oxford University Press. Such an anti-physicalism argument, says Goff, “hangs and falls on Phenomenal Transparency,” and he spends three chapters explaining why.Goff, 17, and chapters 3–5.

Here is the problem. By embracing Phenomenal Transparency, the panpsychist must take the dualist intuition seriously that one’s conception of oneself as a subject of consciousness is likewise phenomenally transparent. Moreover, they cannot avoid this and similar arguments for substance dualism by following the standard physicalist rejection of knowledge by acquaintance with one’s conscious states. See, e.g., Churchland, P. (2013). Matter and consciousness (3rd ed., pp. 24–25). Cambridge, MA: MIT Press Additionally, we will see in Chapter 10 that the rejection of Phenomenal Transparency, and self-knowledge by acquaintance, has unknowingly led many physicalists to promote a grotesque strawman according to which substance dualism commits one to soul-stuff that can only be characterized by way of the via negative.

Embracing a further pro-dualist thesis, some recent panpsychists and non-substance dualists defend non-deflationary accounts of subjecthood. Goff, for example, argues that (direct) Phenomenal Transparency entails a non-deflationary account of subjecthood because it allows one to grasp the essence of any phenomenal property and, in doing so, the essence of subjecthood. This entails that subjects cannot be explained away. Goff, 178–181, 210–211.

To be clear, we are not defending introspection arguments for substance dualism. That will be ventured in Chapter 4. Instead, we are merely pointing out that the current turn toward panpsychism evidences a new acceptance of pro-dualist intuitions (e.g., direct acquaintance with one’s mental states and the irreducibility of phenomenal consciousness), which in turn increases the probability of substance dualism.

Lastly, consider a thesis of Russellian panpsychism.

Opacity of the Physical: While we know the dispositional properties of the physical, we lack knowledge of its qualitative phenomenal properties.

Our knowledge of the physical is so incomplete that we have failed to understand that phenomenal consciousness is an aspect of the physical.

Here comes a problem. If the physical is so opaque as to conceal its phenomenal properties, the standard interaction problem loses its teeth. That form of the interaction problem is motivated by the claim that the mental is too dissimilar from the physical to allow any causal interaction between them. The Russellian panpsychist must hold that we know enough about the physical to motivate the interaction problem while also maintaining that the physical is opaque enough to suppose that matter, in some sense, has phenomenal properties. However, what in-principle reason could be given for thinking that the physical is not so opaque as to blind us to the fact that it cannot causally interact with the mental? Consequently, the recent turn toward Russellian panpsychism increases the probability of substance dualism by significantly weakening a major version of the interaction problem—more on this in Chapter 10.

In summary, substance dualism is returning. The recent move toward panpsychism and Russellian monism signals a growing embrace of pro-dualist intuitions and methodologies, raising the probability of substance dualism. And there is an increasing recognition that we should expect the nature of consciousness to be weird or far stranger than was anticipated in the 20th century. Commenting on the rejection of panpsychism as a crazy view, David Chalmers observes, “While the view is counterintuitive to some, there is good reason to think that any view of consciousness must embrace some counterintuitive conclusions.”Chalmers, Panpsychism and panprotopsychism, 19. That substance dualism strikes some as odd shouldn’t mean much of anything. The 20th-century’s certain-defeat-of-dualism narrative can no longer be presumed. In fact, substance dualism in the 21st century seems quite promising.



1.5.1 Delineating the View

Our goal in this book is to defend substance dualism in its broadest form, what we call Mere Substance Dualism. In general, this minimal thesis is all that most arguments for substance dualism entail and is the starting point for any specific views. Substance dualism, explains Dean Zimmerman, is the view that,

for every person who thinks or has experiences, there is a thing—a soul or spiritual substance—that lacks many or most of the physical properties characteristic of non-thinking material objects like rocks and trees; and that this soul is essential to the person, and in one way or another responsible for the person’s mental life.Zimmerman, D. (2010). From property dualism to substance dualism. Aristotelian Society Supplementary, 84(1), 119–120. See also Zimmerman, D. (2005). Dualism in the philosophy of mind. In D. M. Borchert (Ed.), Encyclopedia of philosophy (2nd ed., Vol. 3, p. 113). Macmillan.

Similarly, William Hart explains substance dualism as the thesis according to which “… each person’s mind is at least not identical with his body, so these are two different things.”Hart, W. D. (1994). Dualism. In S. Guttenplan (Ed.), A companion to the philosophy of mind (p. 265). Oxford: Blackwell Publishers.

This common understanding of substance dualism emphasizes the nature of the self or soul as an immaterial substance and leaves the nature of the body an open question.Those who state SD similarly include Howard Robinson, Geoffrey Madell, and N. M. Nathan. Cf. Robinson, H. Substance dualism and its rationale. In R. Swinburne (Ed.), Free will and modern science (p. 162). Oxford: Oxford University Press; Madell, G. (2010). The road to substance dualism. Royal Institute of Philosophy Supplement, 67, 56; Nathan, N. M. L. (2011). Substance dualism fortified. Philosophy, 86(02), 201. Substance dualism requires the following theses:

(a) The human person (sans disembodiment) is comprised in one way or another of a
soul and a body.We use “comprised” to remain neutral regarding issues of composition or constitution. The substance dualist, qua substance dualist, needn’t commit to such specifics. Moreover, our way of putting it leaves open the possibility that the person is identical to that person’s soul and, in the ordinary scheme of things, has a body that includes physical entities.

(b) The soul is an immaterial substance.Staunch hylomorphists view substantial form as an abstract particular and call it a soul that departs at death and, somehow, sustains absolute personal identity. Here, the soul qua particularized substantial form is substance-like, i.e., it is an incomplete substance that requires a body to form a genuine substance. We include these views within our use of Mere Substance Dualism.

(c) The body is—or at least partially is—a physical entity or an aggregate of physical entities.

(d) In principle, the human person can exist without his/her body.

There are further commitments of substance dualism we should consider.

(e) The mental life of a human person is possessed and unified by his/her soul.

Importantly, (e) does not entail that the soul is fully responsible for one’s mental life but allows the brain and central nervous system (if not the whole body) to play a role in one’s mental life. All that (e) requires is that the soul is necessary for the mental life of a human person.

(f) The soul is fundamental.

Issues of fundamentality are complex. Broadly speaking, we take (f) to mean that the soul is not reducible (ontologically, linguistically, causally, or explanatorily) to anything else.

Taking (a) through (f) together, we get the following thesis:

Mere Substance Dualism (SD): The human person (i) is comprised of a soul (a fundamental, immaterial/spiritual substance) and a physical body, (ii) capable of existing without a body, but not without his/her soul, and (iii) the mental life of which is possessed and unified by his/her soul.

This is the thesis we will defend throughout this book, although, at times, we will include details from specific substance dualist views. We will refer to Mere Substance Dualism as substance dualism or SD for brevity.

In conclusion, many arguments against naturalism and physicalism and arguments for SD are too often neglected in the philosophy of mind. And when these arguments are presented, it is often the case that the presentation is too brief to examine the depth of those arguments. Among other things, we hope to remedy these problems in the following chapters.


1.5.2 The Undeniable Recalcitrance of Substance Dualism

Substance dualism has withstood centuries of objections. It is a minority view with a resurgence underway. SD is almost always dismissed as out of fashion. However, without the dubious assumption that current ideological popularity is a defeater for argument, this dismissal is telling. But suppose that ideological popularity provides some vital evidence against a view. Now the story changes dramatically. SD enjoys greater evidential support than naturalist views, as SD is arguably the most popular view in the entire history of philosophy. And appealing to current ideological fashion’s popularity seems arbitrary, historically chauvinistic, or naturalistically presumptuous.

In the following chapters, we will lay out a detailed, sometimes new, case for SD. But as noted above, we must keep an eye on worldview issues when doing philosophy of mind. Thus, to those issues, we now turn.