Thomism, Hylomorphism, & Personal Identity

Saint Thomas Aquinas the Angelic Doctor BackgroundThe discussion of abortion is usually approached from the context of “rights” following the judicial precedent instituted by Roe v. Wade and Casey v. Planned Parenthood. One of the philosophical presuppositions undergirding the precedent of a right to abortion is the idea of bodily autonomy. For contemporary American culture absolute bodily autonomy is now an unexamined philosophical foundation protected by quips and slogans rather than sound reasoning. Those in disagreement with Roe and the succeeding precedent are faced with the difficult challenge of combatting sophists dedicated to sloganeering while at the same time being expected to perfectly articulate the pro-life position within an often-interrupted sound bite. Attempting to articulate a thorough refutation of abortion rights requires a Sisyphean effort when your arguments are kicked back down the hill every time some feminist shrieks, “My body! My Choice!” or “Free abortion on demand and without apology!”

In order to engage the abortion debate in a meaningful way the philosophical dispute must first be properly identified. The point of stasis is not at the level of political rights, but at the theological and philosophical level of personal identity, or what constitutes personhood. Moreover, to properly discuss personal identity at the philosophical level, metaphysical and ontological commitments must be discussed, which inexorably requires analysis at the theological level. To be sure, theology, metaphysics, and ontology are entirely wrapped up in the discussion of personal identity so these deeper issues are unavoidable.

When discussing issues of personal identity (or personal agency) our culture is systematically trapped in a strict either/or dichotomy. Either our personal identity is associated with our psychological attributes or it is associated with our bodily attributes. In our modern political discourse, there is no middle way offered to untie this tightened secular knot.

Professor Robert P. George argues,

Either the body is a part of the personal identity of the human being, in which case the human person, properly speaking, is a dynamic unity of body, mind, and spirit, or the body is a sub-personal dimension of the human being that functions as an instrument at the service of the conscious and desiring aspect of the self – the ‘person,’ strictly speaking, who controls and uses the body. The secularist position on issues such as abortion, infanticide, and euthanasia straightforwardly treats the body as a sub personal reality: a living human body is not a person, or, at least, is not a person until it comes to be associated (somehow) with a mind or other center of conscious self-awareness; and a living human body ceases to be a person not necessarily by dying, but ay any point at which it loses this association, which may be long after death. The body, as such, according to secularists, lacks the dignity of personhood – that is why they believe it isn’t necessarily wrong to kill ‘pre-personal’ or ‘post-personal’ human beings (fetuses, handicapped infants, the irreversibly demented, or other human ‘nonpersons’).[1]

Professor George continues,

“The dualism of orthodox secularism is not erased by the materialist insistence that the attributes of personhood are, ‘entirely a function’ of the physical structure of the human organism. For secularist liberals, it is the conscious, desiring, self-aware, and future directed part of the human being that is truly the ‘person’; it is the psychological attributes of consciousness, self-awareness etc. that confer ‘moral standing.’ By contrast, the living body, as such, is not part of the personal reality of the human being. And it is the status of the body as sub personal that accounts for the willingness of secularists to authorize the killing of human beings before they become ‘persons’ (fetuses and even infants) and after they cease being ‘persons’ (the demented, the permanently comatose, etc.) The dualism of orthodox secularism consists in treating the ‘person’ and the ‘mere living body’ as really separable. ‘Persons’ have dignity and rights; (their) ‘mere’ living bodies do not.”

Secularists, then, have tied themselves in an incoherent, ad hoc metaphysical knot that only recognizes rights within the dualistic nature of the functional human person (as they conceive of functioning) while denying this same dualistic nature to those they consider pre or post persons. In addition to this confused position, the supposed right to an abortion is associated with the concept of individual bodily autonomy while at the same time personhood is arbitrarily recognized only when conscious self-awareness is attained. To make matters even worse, the secularist view often influenced by materialist presuppositions, usually commits to a form of mind-body monism concerning consciousness, whereby the mind either emerges from matter or under the pretense of functionalism the mind is reduced to physical sensory inputs and outputs. What seems to follow from this secular materialist position is an incoherent appeal to consciousness as the defining attribute of personhood while at the same time reducing consciousness to an effective material illusion derived from biological operating features of the body. For the orthodox secular progressive, the person is defined by a consciousness that is nothing more than a physicalist illusion of chemical interaction.

Only a scholastic orthodoxy, informed by the tradition of Thomistic thought, and guided by the light of the Catholic faith can overcome the dilemma that has enslaved our contemporary modernist culture. In this essay I will articulate a view of personal identity which unshackles itself from the contemporary either/or tradition when considering these issues. After defending this view of personal identity, I will briefly examine how it can be informative when considering moral issues in the public square.

Scholasticism and the Human Person

Why should we utilize Neo-Scholastic Thomism on issues concerning personal identity? Why should we seek guidance from the Patristic Doctors of the Church, and the medieval scholastic theologians and philosophers when we are living in a modern, scientific era? The primary reason for doing so is to offer a philosophical view that is able to break free from the picture of reality our society seems to be trapped in; an unexamined either/or dichotomy between the mental and material instead of considering a both/and approach to personal identity. Moreover, these public policy issues demanding moral clarity are resting upon a more fundamental ontology of person than our public discourse allows. Neo-Scholastic Thomism, in my view, is able to untangle this tightened knot.

Thomism is committed to the theory of hylomorphism.[2] A hylomorphic philosophy of nature is an important component of the traditionally informed worldview, and emphasizes a specific structure and organization of the materials that make up the world we live in.[3] Most importantly, the hylomorphic philosophy of nature is ontologically hierarchic, metaphysically cogent, is consistent with the light of human reason, and participates on the spectrum of revealed truth concerning the created order. The emphasis of a dynamically unified, hierarchic composite structure and organization of the natural world provides ontological explanations for why various organisms possess distinguishing aptitudes for growth and development, reproduction, perception, movement, and cognition.[4] A philosophy of nature informed by the classical tenets of hylomorphic theory not only reconstitutes how it is that we can begin to understand our created reality, it appropriately challenges the mechanistic view of nature that has been popular since the Enlightenment.[5]

The distinctive philosophical principles of the hylomorphic theory of nature important for investigating personal identity are form/matter and potentiality/actuality. Things (objects) in nature are a combination of form and matter. To visualize this, Edward Feser gives an example of a red rubber ball.[6] The matter of the ball all by itself cannot be the ball because the rubber material could be something other than a ball, such as the sole of a shoe. Moreover, the form by itself is not the ball because the form is merely an abstraction that informs the material substance of the thing, in this case it is the red rubber ball. Since this is the case, only the form combined with the matter can give us the red rubber ball.

The red rubber ball can also be utilized in order to understand potentiality and actuality.[7] The red rubber ball has the potential to become a puddle of red rubber goo if heat is applied. When this occurs the red rubber ball’s potential capability of becoming red rubber goo becomes actualized. It is important to note that a potentiality can only become an actuality by something that is already actualized. For example, a match has the potential to melt the red rubber ball, but if the match exists only in the state of potentially hot it cannot melt the red rubber ball. Only when the matches’ potential to become hot is actualized can it then actualize the red rubber ball’s potential gooeyness.

These elements of a hylomorphic philosophy of nature are imperative for understanding the ontology of a person. On this view, man is a perfect, dynamic, and unified composite structure of form and matter, or body and soul. The ontology of personhood is not the body alone because not all bodies (matter) possess life, and it is not the soul (form) alone because the matter individuates the form. Henri Renard says,

“The soul is the active principle of life in the nature of man. It cannot be a body, since many bodies do not live. It is a form, not composed, not extended, not divisible, but simple; for it has neither essential nor quantitative parts.” He continues, “Man is a perfect unit, a composite of soul and body – two principles which form a natural, substantial unit, because they are transcendentally related to each other as act and potency. The soul actuates, the matter individuates; the soul is the principle of intellectual life, but it needs matter in order to know. It’s knowledge, which is primarily that of the corporeal world, is acquired though the instrumentality of the senses. For this reason, the soul needs the body for the extrinsic stimulus, without which it could never perfect itself.”[8]

From this standpoint, the hylomorphic view conflicts with the contemporary emphasis on the psychological component of the person as well as the emphasis on a bodily or “animal” component. Indeed, man is not the soul, but a composite of body and soul and the soul is the act and form of the body.[9]

Now that we have explained the hylomorphic philosophy of nature and the proper framework for the ontology of a person, we can posit the necessary and sufficient conditions for personal identity needed to persist through time.

On Thomism, a person X is identical to Y if and only if the soul and body are unified in a composite structure of body and soul. This conception of the person is able to direct our real world investigations of personal identity issues in a way that relates to our common intuitions.

How Do Our Intuitions Relate to the Thomistic View of Personal Identity?

The Bernard Williams essay, The Self and the Future, presents us with two thought experiments that lend support for the defense of a unified view of personal identity. The first thought experiment (scenario) provides two agents – person A and person B.  These agents have a “mentalistic” transfer of memory data. After the transfer takes place, the data from person B is in the A – body and the data from person A is in the B – body. Before the transfer takes place each person is able to choose which body will be tortured and which will be given $100,000. After the transfer either the A – body containing person B’s data or the B – body containing person A’s data, will have been tortured or received $100,000. The second scenario involves only one agent – person A. This agent is presented with the fact that he is going to be tortured the following day, but before being tortured their memory will be erased. The key element to consider from these two scenarios is that in scenario 1 the torture is far less of a concern than it is in scenario 2. This is based on whether a “mentalistic” component or a “bodily” component is tracked with regard to personal identity. Williams finds there are “first – personal” and “third – personal” concerns with questions about personal identity. Moreover, there are also “mentalistic” and “bodily continuity” considerations involved in examining issues concerning personal identity. Also, with this in consideration, Williams thinks these scenarios should run parallel to one another; the first-personal approach should focus on mentalistic criterion of personal identity and the third-personal approach should focus on bodily continuity. What actually occurs is to the contrary of Williams’s intuition. In the third – personal approach of scenario 1 we track a mentalistic criterion and in the first – personal approach of scenario 2 we track a bodily criterion.[10]

Following the thought experiments, a 6-stage examination of these two scenarios is presented to us in an intensified manner; (i) Person A has an operation resulting in total amnesia; (ii) add character changes; (iii) add fictitious memories; (iv) previous character changes and fictitious memories match someone else’s, namely, person B; (v) not only do the changes and memories match person B they are derived from person B; (vi) same as (v) but done for A to person B’s body.[11] On Williams’s view, there is no reason, in stages (i) – (vi), that we should deny the A-body person is identical to A. Hence, for Williams, there is no reason to deny the A-body person is identical to A in stages (i) – (vi).

Stages (i) – (iii) highlight the fear rationally obtained within scenario 2, that even if we have our memories erased prior to being tortured we still have good reason to fear the pain following the operation resulting in amnesia. Moreover, stage (iv) does very little to change the scenario in a material manner since the only change of condition is the introduction of person B into the stages. According to Williams, we can track our fear through all of these stages. Not only is there no material significance in change from (iii) to (iv), there is no causal condition introduced. Stage (iv) is merely saying we have character traits and memories that match another person’s, but it says nothing of their causal nature, that is, how we acquired them. Having character traits and memories of another person is not enough to introduce meaningful changes to individual personal identity. Williams lucidly points this out in addition to the immaterial nature of change between stages (iii) and (iv). The same can be said from stages (iv) to (v). Although a change persists insofar as a model of causal relation is concerned with character changes and fictitious memories, there is still no material significance between (iv) and (v). Significant qualitative changes have taken place, but there is nothing numerical to lose track of, as far as personal identity is concerned. Since this is the case, according to Williams, there is no reason the fear should be tracked from (i) – (v) but not continue to stage (vi).[12]

Our intuitions are related to the ontic-constraint provided within the scenarios life presents us with. The ontic-constraint can be understood as the ontological idealization of any thought experiment or model of reality being presented in order to examine personal identity issues. If the ontic-constraint is loosened to such a degree that its relation to “how-the-world-works” becomes less conceivable the thought experiment becomes ineffective. On the other hand, if the ontic-constraint is constructed in such a way that it closely matches our intuitions of “how-the-world-works” the thought experiment becomes effective.[13]

Scenario 1 represents a thought experiment that is ineffective. In scenario 1, the presentation can be likened to an amusing science fiction “what if”. The ontological construction of the thought experiment is fashioned in such a way that under consideration it is not taken seriously. This is the case for two reasons; first, the language employed is from the third person perspective making it less personal. We are not considering the data transfer or the element of torture as something happening to us. The second reason is that nobody believes such a thing is even likely to occur. It is not even conceivable to believe that scientists will ever be able to accomplish a data transfer such as this unless the human person and personal identity are mistakenly reduced to the operating functionality of a computer. It may be popular to analyze the mind/body problem from the perspective of hardware and software, but this thought experiment presupposes the legitimacy of modernist dualism. The empirical component of the thought experiment needs to relate to a plausible philosophy of nature. The first thought experiment fails this criterion because it lacks the ability to capture the body as a vital component of our personal identity; namely, it assumes the body (matter) can exist without the soul (form) and under the Thomistic tradition being offered this cannot occur. Our identity is not merely tied to the mentalistic or formal aspect of our human nature, but also, the medium by which our mentalistic content is acquired, which are the senses via the body. The empirical plausibility must relate to the ontic-constraint of the thought experiment in a meaningful way in order to properly grasp the metaphysical nature and ontological structure of personal identity.

Scenario 2 represents a thought experiment that becomes effective because it is related to our personal identity via direct acquaintance in a dynamically unified manner. The ontic-constraint is in line with how our intuitions and experiences are related to the world. The fear derived from scenario 2 is exponentially greater because the ontological structure of the thought experiment strikes at the heart of our direct and privileged access to our identity. This is the case for two reasons; first, the language employed is in first person. Instead of only thinking about some impersonal agent possibly being tortured it is us we have to worry about. And despite all of the qualitative changes that will take place in the experiment, no numerical changes in personal identity occur. If they did, there would be nothing to worry about, yet a lingering fear of being tortured remains. The second reason is the comparative presentation of the scenarios provides adequate reason to believe an operation could be performed that erases my memory, which is then followed by torture. Not only do we fear losing our memory, but we also fear our post-torture qualitative status shaping our metaphysical identity in ways unimaginable pre-surgery and pre – torture.  It is not that we cease to exist and a new identity obtains, rather, it is the case that our qualitative status has changed in traumatic fashion, which all persons deeply fear. The question is not if I will exist; the question is how I will exist. In this scenario the empirical plausibility closely relates to the ontic – constraint of our intuitions and experience of the world. Hence, we are able to detect the importance of a bodily and mentalistic criterion with regard to personal identity, or rather; the Thomistic conception of personal identity being a dynamically unified composite structure of body (matter) and soul (form) is not violated.

Applying Neo-Scholastic Thomism to Different Moral Scenarios

These considerations are beneficial for investigating real world questions pertaining to personal identity. Consider the question of abortion. Often times the arguments in favor of abortion in some way, shape, or form deny the personhood of the fetus. According to Thomism this is mistaken. Since the human person is necessarily a dynamically unified composite structure of body and soul, and these two elements exist at conception, the fertilized ovum all the way to delivery is a human person. The necessary and sufficient conditions for personhood are obtained at the moment of conception. An argument to the contrary of this position would not only ignore the hylomorphic philosophy of nature being endorsed, it also “ignores the fact that the development of the human body is a specifically human function, and therefore requires a human soul.”[14] Hence, we were all once fetuses, and we can successfully track our numerical identity along with our qualitative development if left alone to persist through time. Cutting off this path of development negates the potentiality of consciousness from being actualized in the human person. If we were to associate personhood to an economic actualization such as property ownership, while preventing a human life from actualizing this potential by denying the freedom to “develop” into a property owning person, the system has been arbitrarily rigged in favor of an ad hoc status. To claim a moral right to terminate a life because it has not actualized conscious self-awareness is to presuppose a dubious metaphysical picture of a supposedly recognizable demarcation of life and person.

Another question that is relevant for personal identity is whether or not a person’s identity remains while existing in a vegetative state. On the Thomistic conception of personal identity the answer is, yes. As long as the person is functionally alive, whether naturally or artificially, the body and soul would still be present, which preserves the existence of personhood from time t-1 to time t-n. Some may argue a person in a vegetative state would not be functioning as a human and therefore, even under the Thomistic conception of personal identity, personhood would become obsolete. Although this is something to consider, the argument forgets the important component of potentiality and actuality in the classically organic philosophy of nature. If a human person is unable to actualize a potential function it does not follow that personhood is lost. If this were the case, one could argue that if a person cannot actualize their potential to walk their personhood is lost. After all, the inability to walk is arguably a missing human function. For the same reason this argument would be rejected, the argument applied to a person existing in a vegetative state is rejected as well. Admittedly, losing the function to walk may be too simplistic because a person that is unable to walk may still possess conscious awareness. Instead of the inability to walk, we can consider a person’s inability to use their reason properly. A person that is severely mentally handicapped will never be able to actualize the potential to reason well, but this person is consciously aware of their existence, their surrounding environment, and experiences all the same realities other conscious human persons experience. What they lack is the ability to use their reason. If we were to substitute consciousness with the ability to reason as the defining factor determining personhood, something immediately strikes our moral intuition that it is intrinsically immoral to end the life of a mentally handicapped person because they may never be able to put together a well-formed syllogism.

Another important question is how does Thomism examine what happens at death? On this view of personal identity, the person no longer exists actually; rather, the person exists residually.[15] Person A exists as a composite of F/M (Form/Matter), or F/M unified brings forth the actuality of person A’s existence. At death, F/M are separated, and since the necessary condition for person A to persist through time is the unity of F/M the person cannot be identified solely as F or M. Hence, the person exists residually and not actually.[16]

Finally, we need to briefly examine what we are personally responsible for with regard to our actions. According to Thomism, it doesn’t make sense to talk about “actions of our bodies,” “decisions made by our minds,” “or things we only remember doing.” To ask the responsibility questions this way is to fall into the either/or dichotomy we are looking to avoid. Only human persons act, think, or remember. For example, if a person were to consume too much alcohol, become intoxicated and black – out they would still be responsible for their actions while being blacked – out, even if they did not remember anything in this altered psychological state. Remembering an action is a cognitive feature that can be altered or hindered while under the inebriating effects of alcohol. Nonetheless, it is still the person who acts while inebriated because the soul and body are united. Thomism, then, suggests that there is no way to divide the psychological and bodily components of action, thought, or memory that would relinquish responsibility of actions even while under the influence alcohol.

In this essay I have articulated a view of personal identity associated with Neo-Scholastic Thomism and a hylomorphic philosophy of nature. The strengths of this view are its unification of the human person, constructing thought experiments according to the effective ontic-constraint criterion, and providing philosophically relevant answers to questions about abortion, euthanasia, death, and responsibility of action. Hopefully, this view will become more influential because I think it can yield interesting advancements when answering relevant moral questions being examined in our culture.


– Lucas G. Westman

[1] The Clash of Orthodoxies, Pg. 34

[2] “The term ‘hylomorphism’ is a compound of the Greek words hyle and morph, which are typically translated ‘matter’ and ‘form’ respectively.” (Philosophy of Mind: A Comprehensive Introduction, Jaworski, Pg. 270)

[3] This fundamental understanding of nature has its roots in Patristic thought, and was endorsed by every major Scholastic thinker. St. Bonaventure and St. Thomas Aquinas, both Doctors of the Church, endorse a hylomorphic philosophy of nature despite their nuanced differenced due to commitments with the Platonic and Aristotelian traditions respectively.

[4] Philosophy of Mind: A Comprehensive Introduction, Jaworski, Pg. 270

[5] The orthodox mechanistic ontology of nature is beginning to be challenged by various philosophers. Some of them are Edward Feser, David Oderberg, William Jaworski, Tuamoa E. Tahko, and E.J. Lowe. Although it may not be formally recognized as such, a structural view of nature similar to hylomorphism is popular among philosophers of biology, biologists, and other scientists. William Jaworski references this situation in his book, Philosophy of Mind: A Comprehensive Introduction, Pgs. 271, 275, 276, 284, and 285. Even Thomas Nagel challenges the mechanistic understanding of nature in his highly controversial book, Mind and Cosmos.

[6] Aquinas, Feser, Pg. 13

[7] Feser also uses the red rubber ball to explain potentiality and actuality, and I am using his example.

[8] The Philosophy of Man, Pg. 37, 38

[9] The Philosophy of Man, Renard, Pg. 40, 42

[10] Williams, Bernard (1970). The Self and the Future. The Philosophical Review, 79(2), 179

[11] Williams, Bernard (1970). The Self and the Future. The Philosophical Review, 79(2), 172

[12] Williams, Bernard (1970). The Self and the Future. The Philosophical Review, 79(2), 17, 172, 174

[13] The term ontic-constraint and the phrase “how-the-world-works” is taken from Uskali Maki’s essay “The Way the World Works (www): Towards an Ontology Theory Choice.”  This essay is found in Maki’s book The Economic Worldview: Studies in the Ontology of Economics. In this essay Maki employs these terms to argue when choosing between models of economic theory the ontology of the model is highly relevant for which theory is the better theory. I find this to be an important insight when considering thought experiments in personal identity issues.    

[14] Reasonable Faith, Haldane, Pg. 138

[15] This could be understood as “continuity” vs. “connectedness.” At death, we would no longer exist in continuity as person A. Our residual personhood at death would only have features of connectedness to person A.

[16] John Haldane explains death in the Thomistic perspective in a way similar to this. I am borrowing his terminology to explain it in a way that better fits this essay, Reasonable Faith, Pg. 158.


Feser, E. (2009) Aquinas. Oxford, England: Oneworld

Jaworski, W. (2011) Philosophy of Mind: A Comprehensive Introduction. West Sussex, United Kingdom: Wiley – Blackwell

Benignus, B (1947) Nature, Knowledge, and God. Milwaukee, WI: The Bruce Publishing Company

Renard, H. (1948) The Philosophy of Man. Milwaukee, WI: The Bruce Publishing Company

Williams, Bernard. The Self and the Future. The Philosophical Review, 79(2)

Maki, Uskali.  The Way the World Works (www): Towards an Ontology Theory Choice.  The Economic Worldview: Studies in the Ontology of Economics

Haldane, J. (2010) Reasonable Faith. New York, NY: Routledge

4 thoughts on “Thomism, Hylomorphism, & Personal Identity

  1. I would be curious as to what you think about spiritual matter. The Bonaventurians generally argue that it is more consistent with Aristotle than is the Thomist position. It was held by all Franciscan thinkers prior to Scotus, and, though there is no research on this, for quite a while afterwards and was revived later. Even Scotus never directly attacks it, though he does not endorse it either.


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