Homoousios Doctrine and Non-Reductive Models of Consciousness: An Orthodox Christian Look at the Mind/Body Problem

In his article “Consciousness and Its Place in Nature,” David Chalmers goes beyond what his introduction suggests of presenting an overview of the principal issues concerning the metaphysics of consciousness.  He begins by offering three epistemic arguments against reductive materialist solutions to the problem of consciousness, outlining three basic objections to these arguments, and then pointing out the fatal flaws of these objections.  He concludes with a look at three non-reductive views, and while endorsing none as the much sought-after solution, concedes that at least none possesses fatal flaws.

Both aspects of this article are of considerable interest to Christians and Christian philosophers.  For some, the Christian faith is predicated on substance dualism,[1]  and given the vigorous attacks on substance dualism, both in academic philosophy and the more mainstream press,[2] any serious critique of the variations on reductive materialism is important.  In addition, Chalmers presents a clear outline of viable, non-reductive models, including a type of dualism, which can well guide further thought regarding the mind/body problem, consciousness, and the soul.  That any attempts at understanding the nature of the soul are important for Christians and Christian philosophers is obvious, but that it should fall along with consciousness under the umbrella of the mind/body problem is an idea that can be traced at least as far back as Tertullian, who writes, “We, however, say that the mind has coalesced with the soul, not as something other in substance, but as the function of that substance.”[3]  The question that immediately arises, then, is how the truth of Christian revelation can return the favor by guiding exploration among Chalmers’ three viable alternatives in this area of the philosophy of mind.

This article will attempt to evaluate those non-reductive alternatives in light of the homoousios[4] doctrine of the orthodox Christian faith.  In particular it will explore whether a model other than substance dualism may be consistent with the truth about the nature of God revealed in the Incarnation of Jesus Christ, and thus a reasonable model to explore in consciousness studies.

As for the methodology of this paper, it is important to consider why this approach, i.e. exploring the mind/body problem through the self-revelation of God, is an appropriate one.  Pope famously cautioned, “Know then thyself, presume not God to scan/The proper study of Mankind is Man.”[5]  This caveat, however, presupposes a dichotomy between divine and created nature that is not supported by orthodox Christian faith.  In Tertullian we read, “Certainly one will find no other more powerful expositor of the soul than its Creator.  From God one should learn about what one has from God, and from no other, if not from God.”[6]  If God, rather than man, is the creator and measure of all that is, and indeed Christians affirm this,[7] then it seems only reasonable and practical to examine what God has to say on the matter, through His inspired Word, through the words of His inspired servants, and through His self-revelation in the Incarnation of His Son.

With regard to this latter form of divine communication, it is my thesis that the human creature is substantially similar to its Creator.  Explicitly in  Genesis 1:26 and implicit throughout the rest of the Bible is the idea that human beings were created in the image of God.  I take a strong interpretation of “image” here, in the sense of sharing a similar substance.  It is beyond the scope of this article to detail thoroughly the biblical support for this foundational thesis, but to take one example from the New Testament and draw some quick implications, I shall refer to Hebrews 2:11.  “Both the one who makes men holy and those who are made holy are of the same family.  So Jesus is not ashamed to call them brothers.” (NIV)  The Greek translated “of the same family”, “ex henos pantes,” literally means “all out of the one.”  There is a much closer connection between the human creature and God than exists between a statue of a human and its sculptor.  Whereas the statue bears accidental similarity to its sculptor, the human creature embodies a substantial likeness to God.

In the writings of the early church Fathers, we see this close similarity between the substance of the human creature and the substance of God.  Of the human creature Tertullian writes, “Therefore, if he is the image of the Creator (for He, gazing upon Christ, His word, about to become a man, said, “Let us make man according to our image and likeness . . . .”[8]  He continues this thought later by saying, “At any rate, that which He formed, He made according to the image of God, which is to say of Christ.  For the Word was also God . . . .”[9]  It is significant that Tertullian focuses on the eternal relationship of God the Father and God the Son as that in which the human creature is the image.  It is not some vague notion of deity, or some performance aspect of the divine nature such as the ability to create that humankind is seen to resemble, but the divine ousia, or essence itself, and explicitly that essence as it has come to be known through the Incarnation of Jesus Christ.  As the word “also” in the latter Tertullian citation suggests, so the word homoousios implies distinction between those things that are being compared as homos, and yet Tertullian, as do all other orthodox Christian writers, clearly indicates identity of Jesus with God, and it is with this nature explicitly considered that he makes the connection between the nature of the human creature and God.  In his argument for the incorporeity of the soul, Gregory of Nyssa acknowledges similarly, “For that which has been made according to His image throughout all its parts has altogether a similarity to its archetype, having an intellectual faculty from its intellectual faculty and from its incorporeal nature drawing its own incorporeity, not fashioned of any kind of weight, just as its archetype is not, and eluding any indicating measurement as does its archetype….”[10]  Finally, we see this idea of substantial similarity extended to the rest of creation in Irenaeus.  “…He made all things…saying, ‘Let us make man according to our image and likeness;’ He Himself taking from Himself the substance of the creatures, and the pattern of things made, and the form of all adornments in the world.”[11]

Given this substantial similarity between the human creature and God, anthropos homoiousios theo, as it were, we can then look to the nature of God as He Himself has revealed that nature for possible models to understand our own nature, especially such seemingly disparate aspects as mind and body.  Since God has revealed His nature in the Incarnation of Christ, and has inspired human understanding of that nature through the language of homoousios to patri, it is reasonable to extend this model, given anthropos homoiousios theo, to humankind itself and to consider the look of the mind/body problem when viewed through its lens.

Consider now the three non-reductive models of consciousness that Chalmers puts forth as having no inherent fatal flaws.  Going out of the order in which he presents them, let us begin by taking a look at what he terms type-E dualism, or epiphenomenalism, i.e. the belief that the physical causes the phenomenal, but the phenomenal cannot cause the physical.  For example, what caused the Good Samaritan in the parable to cross the road and help the man who had been beaten?  Common answers may assign causality to emotion or reason, citing his compassion for any wounded person, or his consideration that the injured man might repay his kindness.  A typically Christian response would be that God moved him in his spirit to show generosity.  According to epiphenomenalism, none of these phenomena of emotion or reason or spiritual motivation are capable of exerting causal force over they physical.  The experienced fact of one or more of these states occurring every time the Samaritan saw a person in need would have been at best a coincidence of states and actions, but does not imply that any one of the former actually caused the latter.

We consider type-E dualism first because it is the most obviously incompatible with what we know of the nature of God.  Following the thesis of the substantial likeness of human beings with God, it follows that if epiphenomenalism is incompatible with the nature of God, it is likely incompatible with the nature of a human.

Philosopher of mind Jaegwon Kim has famously put forth what he calls Alexander’s dictum:  To be is to have causal powers.[12]  Once again, looking to the first chapter of Genesis in particular, and throughout the Bible, it can be seen that God’s causal power forms the warp and weave of the ongoing story of creation.  Religion and philosophy professor Dennis Bielfeldt recognizes that the three major monotheistic religions of Judaism, Christianity, and Islam, all must develop an understanding of the world that avoids a causally inert deity.[13]  Approaching this issue from within the Christian faith, however, we see that what is at stake is more than merely creating a philosophy that allows for divine causal activity.  To the degree that the Christian faith understands truth at all, and indeed of all the monotheistic religions it puts forth the strongest epistemological claim by asserting that its deity is not only the embodiment of truth but also the sole access to it,[14] a causally active deity is a given, both within creation and within the hypostatic union of Himself as Trinity.[15]  Given the genuine intra- and interpersonal causality brought about by the triune Christian God, such causal power cannot be seen as epiphenomenal, and given our foundational thesis, it is unlikely for epiphenomenalism to describe causality within the human nature.

Bielfeldt, however, suggests that the only way for the three great Western monotheisms to avoid a causally inert deity is to accept substance dualism, what Chalmers discusses under the heading of type-D dualism, and to which we now turn.  Chalmers focuses here on interactionism, or the causality of the physical on the mental, and vice versa.  Whether one takes the “D” in type-D dualism to stand for “Descartes,” the most familiar proponent of substance dualism, or to stand for “downward causation,” a principle often invoked when considering property or emergentist dualism, it is the role of the phenomenal on a non-causally closed physical realm that Chalmers offers as a possible model for understanding consciousness.

He acknowledges the common objection that no causal nexus can be identified through which the phenomenal and physical could reciprocally interact, but observes that the same can be said for the physical alone.  He notes, “Newtonian science reveals no causal nexus by which gravitation works, for example; rather the relevant laws are simply fundamental.”[16]  John Foster takes a similar stand in questioning whether the interactionist question poses an a priori problem at all.  Many philosophers, according to Foster, take the problem of interactionism to be self evident on the grounds of their conditioning by experience of the ways in which causality works in the physical.  Because examples of purely physical causation seem to take place only through spatial contact, it is assumed that all causation must employ necessary spatial contact.  This, however, is an example of post hoc ergo propter hoc, and Foster considers an earlier model of gravitation that construed causality over distance without any spatial contact.  That this model has now been rejected is irrelevant, for he notes, “…even if physical causation typically, and perhaps always, operates through spatial contact, it is certainly conceivable, and unproblematically conceivable, that it should sometimes not.”[17]  His point is weakened, however, when he offers an example of what could pass for evidence of such spatially non-contiguous causality.  Here he suggests, “a constant correlation between the occurrence of the one type of event and the immediately subsequent occurrence of the other, an inability to detect any intervening mechanism, and an inability to provide a causal explanation of the second event in any other way.”[18]  This, it seems, is but a version of the physicalist argument against interactionism used in its defense.

Chalmers offers a far stronger rebuttal to the physicalist, one that draws from the very principles of physics an encouraging possibility for interactionism.[19]  Quantum mechanics suggests that the state of the physical world can be described by a wave function, but one that can evolve in two rather different ways.  One is a linear evolution described by the Schrödinger equation, the other is an evolution of collapses from superposed states into nonsuperposed states.  These collapses happen only occasionally, and only upon measurement.  Regardless of the specific definition one uses for “measurement,” it must include the idea of conscious observation.  Thus, per his explication, the laws of quantum mechanics themselves invite the prospect of consciousness exerting causal force on the physical.  Chalmers admits that this may not yield the sort of causal role for consciousness that may be expected, but he does manage to show that there is no a priori reason to reject a type-D dualistic interactionism.

How does this relate to the nature of God?  The western monotheisms believe in and worship a transcendent deity.  Transcendence seems to entail being wholly other, and this could, and often does, suggest a substance dualism between God and His creation.  Bielfeldt considers this to be inherently problematic, for if God is to have causal powers, and by Alexander’s dictum He must if He exists, then the believer is led to reject the causal closure of the physical.  He writes, “Because all causal influence with which we are familiar is mediated through the transfer of energy, there must be some energy transfer from God into the universe [i.e. when He exerts causal power over the physical].  But…this clearly violates physical conservation principles….”[20]  The believer is then left with “the possibility of information transfer without energy transfer.”[21]

He goes on to consider that one way out of this trap would be through the indeterminacy of quantum mechanics.  Referring to William Pollard’s Chance and Providence, he recognizes that “because an electron in a superposition of states has no definite position, no energy is required for God to actualize one among the set of its possibilities.”[22]  He finds this, too, problematic, for it would mean that God’s causal powers could be effected only during moments of measurement, which is to say, conscious perception.

This line of reasoning sounds suspiciously like Berkeley’s esse est percipi, and the responding limericks of Monsignor Knox are equally appropriate here.[23]  A stronger objection would again be the challenge Chalmers raised regarding measurement in quantum theory as the vehicle for conscious causality on the physical.  Is this the sort of causality we are looking for?  Certainly throughout Scripture, and throughout countless sacred writings and the experiences of many through the ages, God has demonstrated dramatic causal ability, but this seems to be of a kind more than what would be reasonable through the mere resolution of superposed electron states.

With regard to what Chalmers refers to as type-D dualism in Chalmers (2002), he terms “naturalistic dualism” in Chalmers (1996) and describes as being a kind of property dualism.  Importantly he says that “the phenomenal properties . . . are ontologically independent of physical properties.”[24]  He suggests that while not being of a different substance from the physical, phenomenal properties are ontologically novel because they are not logically supervenient[25] on the physical, and therefore are in a much stronger sense nonphysical than, say, a property such as biological fitness, which does supervene logically on the microphysical.[26]  Given our thesis of anthropos homoiousios theo, especially when set in contradistinction to the more robust homoousios truth revealed through the Incarnation, we can see a plausible model for type-D, naturalistic dualism.  Referring again to the statement by Irenaeus about God’s taking of Himself the substance of creation, that creation is clearly ontologically novel with respect to God, and yet not of an entirely different substance, thus making anthropos to be homoiousios with respect to God.  In similarity, then, to this relationship of similarity between God and creation, it is entirely conceivable that the creation itself bear the marks of that relationship, expressing this similarity through the naturalistic dualism of the phenomenal and the physical.  In this regard it is the homoios relationship itself that provides the model for the relationship of phenomenal and physical.

But what if it is divine ousia itself, that to which anthropos is homoiousios, that is the model for understanding the created, especially the human, ousia?  Chalmers recognizes that what he has viewed as a variety of dualism could in fact be revealed as a type of monism.  He writes, “Perhaps the physical and the phenomenal will turn out to be two different aspects of a single encompassing kind, in something like the way that matter and energy turn out to be two aspects of a single kind.”[27]  In Chalmers (2002) he terms this type-F monism and describes it simply as “the view that consciousness is constituted by the intrinsic properties of physical entities….  On this view, phenomenal and protophenomenal properties are located at the fundamental level of physical reality, and in a certain sense, underlie physical reality itself.”[28]  This is a form of what is known as panpsychism, regarding which Chalmers speculates, “Panpsychism is simply one way that the natural supervenience of experience on the physical might work.  In a sense, natural supervenience provides the framework; panpsychism is just one way of working out the details.”[29]  Chalmers indicates that he does not advocate the term “panpsychism,” in part because it suggests experiences in simple systems such as atoms, leading to counterintuitive questions such as, “What is it like to be an electron?”[30]  Instead he puts forward type-F monism as panprotopsychism, which eliminates the notion of experience at a primary level, but retains the idea that in addition to intrinsic properties of the physical such as spin, charge, and the like there are also protophenomenal properties out of which arise or on which are supervenient conscious experience.

Can this type-F monism be compatible with what we know of the nature of God as He has revealed Himself?  As expressed in the Nicene-Constantinopolitan Creed, the orthodox catholic Christian faith believes that Jesus Christ is “of one substance with the Father,” or homoousion to Patri.  This has led to the Trinitarian formula of “one being, three persons,” or mia ousia, treis hypostaseis, but what does this really mean?  With regard to this formula in his 1887 introductory essay to Haddan’s English translation of Augustine’s De Trinitate, Dr. William Shedd agrees that “as he that denies this fundamental article of the Christian religion may lose his soul, so he that much strives to understand it may lose his wits.”[31]  In his book The Trinitarian Faith, T. F. Torrance attempts a guide through this doctrine that presumably will not lead to insanity, in part by exploring consequences of this doctrine.  Looking at the key terms ousia and hypostasis, he uncovers the following:

The meanings of ousia and hypostasis…underwent a radical change through the use to which they were put in the hermeneutical and theological activity of the Church.  The homoousios to Patri was revolutionary and decisive:  it expressed the fact that what God is ‘toward us’ and ‘in the midst of us’ in and through the word made flesh, he really is in himself; that he is in the internal relations of his transcendent being the very same Father, Son and Holy Spirit that he is in his revealing and saving activity in time and space toward mankind.

In precise theological usage ousia now refers to being not simply as that which is but to what it is in respect of its internal reality, while hypostasis refers to being not just in its independent subsistence but in its objective otherness.

If God is in himself what he is in the Person and activity of his incarnate Word and Son, then the being or ousia of God must be understood in a very un-Greek way.  Applied to God enousios logos and enousios energeia express the fact that the being of God is not intrinsically empty of word or activity, not mute or static, but is essentially eloquent and dynamic.[32]

Torrance reveals a number of thoughts in the homoousios doctrine relevant to our discussion here.  First is the change in understanding of the word ousia, or “being,” that followed the Incarnation.  It is important to note that Torrance does not say that ousia itself has changed, but that our understanding of it has, and in a radical way.  No longer are we confined to a limited, static understanding of this fundamental word, but we are invited to consider ousia as a dynamic, polyhypostatic union.  This opens up consideration of one fundamental essence with ontologically novel properties, or hypostatic objective otherness, as Torrance would describe it.

Clearly this understanding is capable of embracing type-D naturalistic dualism, but it is also capable of supporting panprotopsychism, or type-F monism.  As this latter model posits the notion of ontologically novel fundamental properties of one physical ousia able to interact with each other, so the homoousion, as Torrance demonstrates, posits the ousia of God, to which we have already noted anthropos is homoiousios, as one of dynamic interaction of distinct hypostases.  Thus, the similarity that allows anthropos to be homoiousios theo finds expression in the dynamic hypostatic union of the created mind/body, which is in parallel to the nature of God as he is ”in the internal relations of his transcendent being”, as revealed in the Incarnation, and as given expression through the language of the Nicene-Constantinopolitan creed and various patristic works.

In conclusion, we can see that a strong interpretation of what it means for the human creature to be created in the image of God, taken together with the truth about the ousia of God revealed through the homoousion and the implications of that revelation for such key terms as ousia and hypostasis, allows for either the naturalistic dualism of Chalmers’ type-D dualism or the panprotopsychism of his type-F monism to be plausible models for understanding consciousness.  If further study should lead to acceptance of the former, it can be seen as fully compatible with a relationship of similarity between the human and the divine, two ontologically novel entities that are yet of one substance.  If the latter model should prevail, it, too, would be consistent with what we know of the divine essence itself, a dynamic and polyhypostatic union to which the human essence has been created in the image.


Bielfeldt, Dennis.  “Can Western Monotheism Avoid Substance Dualism?” 

Zygon: Journal of Religion and Science. Vol. 36, No. 1, March 2001.

Chalmers, David J.  The Conscious Mind:  In Search of a Fundamental Theory. 

Oxford:  Oxford University Press, 1996.

“Consciousness and Its Place in Nature”  Philosophy of Mind: 

Classical and Contemporary Readings, D. Chalmers, ed., Oxford:  Oxford University Press, 2002.

Foster, John. The Immaterial Self: A Defence of the Cartesian Dualist Conception of

Mind.  London:  Routledge, 1991.

Kim, Jaegwon. Supervenience and Mind: Selected Philosophical Essays. Cambridge:

Cambridge University Press, 1993.

Migne, J.-P., ed.  Patrologiae Graecae Tomus 46, Opera Gregorii Nysseni.  Turnhout,

Belgium:  Brepols, 1959.

Patrologiae Latinae Tomus II, Opera Tertulliani.  Paris:  Garnier Brothers,


Patrologiae Graecae Tomus VII, Opera Irenaei.  Paris:  Garnier Brothers, 1857.

Schaff, Philip, ed.  Nicene and Post-Nicene Fathers, Volume 3, First Series. 

Peabody, Massachusetts:  Hendrickson Publishers, Inc., 1995.

Torrance, T. F. The Trinitarian Faith.  Edinburgh, Scotland:  T&T Clark, 1993.

[1] See Dennis Bielfeldt’s “Can the Western Monotheisms Avoid Substance Dualism?”, which he answers in the negative.

[2] See such works as Steven Pinker’s How the Mind Works, Daniel Dennett’s Consciousness Explained, and Antonio Damasio’s The Feeling of What Happens.

[3] De Anima, XII.6 – “Nos autem animum ita dicimus animae concretum, non ut substantia alium, sed ut substantiae officium.”  All translations of patristic sources are my own.

[4] Given the familiarity of the adjective homoousios, I shall use it throughout this paper in its nominative, singular, masculine form when referring to English words. When referring to an independent concept it will appear in its nominative, singular, neuter form, homoousion.

[5] Alexander Pope, Essay on Man II.1-2.

[6] De Anima, I.1 – “Certe nullum alium potiorem animae demonstratorem quam auctorem reperiet; a Deo discat quod a Deo habeat; aut nec ab alio, si nec a Deo.”

[7] “Through him all things were made; without him nothing was made that has been made.”  (John 1:3, NIV)

[8] Adversus Marcionem, V.8 – “Igitur si Creatoris est imago (ille enim Christum Sermonem suum intuens hominem futurum:  ‘Faciamus,’ inquit, ‘hominem ad imaginem et similitudinem nostram’)….”

[9] De Resurrectione Carnis, VI – “Id utique quod finxit , ad imaginem Dei fecit illum, scilicet Christi.  Et Sermo enim Deus, ….”

[10] De Anima et Resurrectione, 380-384c – To gar kat’ eikona genomenon dia panton exei pantos ten pros to archetupon homoioteta, noeran tou noerou, kai tou asomatou asomaton, ogxou te pantos apellagmenon hosper ekeino, kai pasan ekpheugon dia semantiken katametresin homoios ekeino….

[11] Contra Haereses, IV.20.1 – “…omnia…fecit…dicens:  ‘Faciamus hominem ad imaginem et similitudinem nostram;’ ipse a semetipso substantiam creaturarum, et exemplum factorum et figuram in mundo ornamentorum accipiens.”

[12] Kim, 348.

[13] Bielfeldt, 153.

[14] “Jesus answered, ‘I am the way and the truth and the life.  No one comes to the Father except through me.’”  (John 14:6, NIV)

[15] “And I will ask the Father, and he will give you another Counselor to be with you forever – the Spirit of truth.”  (John 14:16-17, NIV)  Not only does God interact with humankind through the Third Person of the Trinity, but this verse also shows a causal relationship among all three Persons.

[16] Chalmers (2002), 27.

[17] Foster, 160.

[18] Ibid.

[19] Chalmers (2002), 28-29.

[20] Bielfeldt, 154.

[21] Bielfeldt, 160.

[22] Bielfedlt, 162.

[23] There once was a man who said, “God

Must think it exceedingly odd

If He finds that this tree

Continues to be

When there’s no one about in the Quad.”


“Dear Sir:

                Your astonishment’s odd:

                I am always about in the Quad

                                And that’s why the tree

                                Will continue to be,

                Since observed by,


                                Yours faithfully,


[24] Chalmers (1996), 125.

[25] Chalmers (1996), Chapter 4 explains quite well various kinds of supervenience.  To give a brief summary, B logically supervenes on A if it is inconceivable that two situations are identical with respect to A, but different with respect to B.  It is conceivable that two humans could be identical with respect to the construction of their brains and yet have different experiences of the same event, thus making phenomenal experience not logically supervenient on the physical.  It is important to note that the term “logical” here refers to what can be conceived rather than to the rules of formal logic.

[26] Chalmers (1996), 124-125.

[27] Chalmers (1996), 129.

[28] Chalmers (2002), 33.

[29] Chalmers (1996), 299.

[30] Chalmers (1996), 299; Chalmers (2002), 35.

[31] Nicene and Post Nicene Fathers, Vol. 3, Series 1, p. 3.

[32] Torrance, 130, 131.

Steve Perkins is teacher of Latin and Theory of Knowledge at North Central High School in Indianapolis and serves as elder at New Life Community Church.

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