For the past several years, I have been pursuing two main research tracks: one in contemporary metaphysics and one in medieval metaphysics.

My contemporary research track pertains to material objects: how they are related to their parts, how they persist through time, and what sorts of material objects there are. Here my most notable contributions are to the growing contemporary literature on hylomorphism, the theory according to which objects are best understood as composed of both matter and form. In a series of publications derived from my earlier dissertation (most notably, “Three Concerns for Structural Hylomorphism”, “From Potency to Act: Hyloenergeism”, and "Trust the Process? Hyloenergeism and Biological Processualism"), I have argued that structural and powers approaches to understanding the notion of form, according to which the form of a material object is best understood as a certain kind of structure, relation, or power realized by, or present in, its material parts, face several serious difficulties. In their place, I have proposed that we think of the form of a material object as a certain kind of process or activity taking place in its matter. Arguing for such an approach requires taking a deeper look at the recent literature on events, processes, activities, and other species of “occurrents”. I am currently working on a book-length articulation and defense of a "hyloenergeic" conception of material objects, tentatively titled: Form as Activity: Hyloenergeism.

My medieval research track pertains to the thought of Thomas Aquinas: how he understands the relationship between material objects and their parts, how he sees objects as persisting through time, and what sorts of material objects he thinks there are. Here my work contributes to the growing literature on medieval mereology. In a series of publications derived from my earlier dissertation (most notably, "Accidental Forms as Metaphysical Parts of Material Substances in Aquinas’s Ontology", "Thomas Aquinas and the Complex Simplicity of the Rational Soul", "Thomas Aquinas on the Metaphysical Structure of Artifacts" and "Thomas Aquinas on Concrete Particulars"), I have been exploring Aquinas’s views on the relationship between substances and artifacts and their formal and material parts. I am currently working on a book-length treatment bringing all of these discussions together on Aquinas on parts and wholes, tentatively titled: Parts, Powers, and Principles: The Mereological Ontology of Thomas Aquinas.

Outside of these two main research tracks, I regularly pursue projects in the philosophy of the human person, bioethics, philosophy of religion, and philosophical theology. I like to try to bring metaphysical views and perspectives explored in my other work to bear on issues within these other subdisciplines. So, for example, I have published papers on animalism and brain transplants, personal identity and the metaphysics of gender, the metaphysics of monozygotic twinning, and free will in philosophical theology.

I've also recently developed a fascination with the thought of Gottfried Wilhelm Leibniz. I'm especially interested in his theory of "superessentialism", according to which every event that occurs in the life of a person is essential to that person, is a part of what makes that person the particular person that he or she is. Recently, I have been thinking and writing about how best to understand and apply that theory. But that project is still in its early stages. I don't know what, if anything, will come of it!

For more information on my published or forthcoming articles and current research projects, please see the descriptions below. Here you will find titles and abstracts for several of my past, present, and future works. Feel free to also email me for drafts of other papers not listed here.

Published and Forthcoming Articles:

"Three Lingering Concerns for Hume's Bundle Theory of the Human Person", Hume Studies (forthcoming).

Abstract. Numerous concerns have been raised for Hume’s positive account of personal identity, his bundle theory of the human person. Some of these concerns are pitched as the very concerns that Hume has in mind when he later backs off from his earlier conclusions in the Appendix. Others are pitched as standalone concerns. In this paper, I focus on the latter. Here I discuss three lingering concerns for his bundle theory of the human person, which I call The Problem of Reference, The Problem of Persistence, and The Problem of Individuation. I argue that, despite recent attempts by various authors to address or dissolve these concerns for Hume’s account, Hume’s bundle theory of the human person remains, in at least three different ways, either inconsistent with his larger philosophical system or incapable of preserving some of our most important attitudes, expectations, and practices concerning the identity of human persons.

"Reduce, Reuse, or Recycle? Animalism vs. Thomistic Hylomorphism", Dialectica [Special Issue on "Thomism Today"] (forthcoming).

Abstract. Animalism and Thomistic hylomorphism share a lot of common ground. The primary disagreement between the two is Thomistic hylomorphism’s claim that every human animal possesses an immaterial part, a rational soul, which serves as the metaphysical ground for her identity over time. In this paper, I argue that Thomistic hylomorphism’s commitment to a non-reductionist, further fact theory of personal identity over time allows it to avoid two major worries for animalism: the problem of indeterminacy and the problem of fission. This leaves animalists with a kind of dilemma: either forego reductionism and reconceptualize the continuity of a human organism’s life in non-reductionist terms, in which case animalism turns out to be not very different at all from a kind of hylomorphism, or continue to conceptualize the continuity of a human organism’s life in reductionist terms, in which case Thomistic hylomorphism has the advantage over animalism in that it avoids two major worries for its closest competitor.

"The Virtues of Superessentialism", Proceedings of the American Catholic Philosophical Association (forthcoming).

Abstract. Superessentialism is the view that every event that occurs in the life of a person, everything that happens to him or her and every decision and action that he or she performs, is essential to that person, is constitutive of that person’s identity. According to superessentialism, it is metaphysically impossible for a person’s life to have gone any differently than it in fact did. In this paper, I argue that, despite its initial implausibility, superessentialism opens up new solutions to three well-known problems in the philosophy of religion: the problem of freedom and creation, the grounding problem for Molinism, and the problem of eternal separation. As a result, while superessentialism might strike many of us as implausible, it possesses an impressive amount of utility. And, for that reason, I think that it might be worth a second look.

"What Happens When the Zygote Divides? On the Metaphysics of Monozygotic Twinning", The Journal of Medicine and Philosophy (forthcoming). [Online First]

Abstract. It is often argued that certain metaphysical complications surrounding the phenomenon of monozygotic twinning force us to conclude that, prior to the point at which twinning is no longer possible, the zygote or early embryo cannot be considered an individual human organism. In this essay, I argue, on the contrary, that there are in fact several ways of making sense of monozygotic twinning which uphold the humanity of the original zygote, but also that there is no easy answer to what happens when the human zygote twins. All of the options available carry with them one or more surprising, alarming, or otherwise counterintuitive implications. All things considered, I conclude that the “budding option”, according to which the original human organism present before twinning carries on as one of the resulting embryos but not the other, is the most plausible explanation of what happens when a human zygote twins.

"Thomas Aquinas on Concrete Particulars", American Catholic Philosophical Quarterly, Vol. 98, No. 1 (Winter 2024): pp. 49-72. [Winner of the 2023 Rising Scholar Essay Contest] [Published Version]

Abstract. There are two competing models for how to understand Aquinas’s hylomorphic theory of material substances: the Simple Model, according to which material substances are composed of prime matter and substantial form, and the Expanded Model, according to which material substances are composed of prime matter, substantial form, and all of their accidental forms. In this paper, I first explain the main differences between these two models and show how they situate Aquinas’s theory of material substances in two different places within the contemporary debate on concrete particulars, highlighting several advantages that Aquinas’s approach has over other varieties of substratum and bundle theory along the way. I then offer some reasons to think that the Expanded Model, as a theory of concrete particulars, is a preferable model. I argue that the Expanded Model avoids two major concerns for the Simple Model: the problem of extrinsicality, and the problem of too-many-possessors.

"Priority Perdurantism", Erkenntnis, Vol. 89, No. 4 (Apr., 2024): pp. 1555-1580. [Published Version]

Abstract. In this paper, I introduce a version of perdurantism called Priority Perdurantism, according to which perduring, four-dimensional objects are ontologically fundamental and the temporal parts of those objects are ontologically derivative, depending for their existence and their identity on the four-dimensional wholes of which they are parts. I argue that by switching the order of the priority relations this opens up new solutions to the too many thinkers problem and the personite problem – solutions that are more ontologically robust than standard maximality solutions. I then consider and respond to two initial objections to the view: that it no longer counts as a perdurantist theory and that it reintroduces the problem of temporary intrinsics. I conclude by offering two further advantages of Priority Perdurantism: that it is consistent with hunky time and with the existence of irreducibly temporally-extended actions, such as those pertaining to deliberative agency.

"Trust the Process? Hyloenergeism and Biological Processualism", Ratio, Vol. 36, No. 4 (Dec., 2023) [Special Issue on “Return to Form”]: pp. 334-346. [Published Version]

Abstract. In this paper, I propose a theory of living organisms that captures the insights of both traditional Aristotelian hylomorphism and John Dupré’s “biological processualism”. Like traditional Aristotelian hylomorphism, the proposed theory understands material objects to be comprised of both matter and form. Unlike contemporary structural varieties of hylomorphism, however, it does not understand the form of a material object to be a relation, configuration, or structure exhibited by its parts but an activity or process in which its matter is continuously engaged. Following Mark Steen, I call the proposed theory “Hyloenergeism”. As a version of hylomorphism, hyloenergeism better captures the inherent dynamism of living organisms than contemporary structural approaches. And it does so not by abandoning the substantialist paradigm, as Dupré’s biological processualism does, but by reconceptualizing the nature of material substances as possessing a processual core. Hyloenergeism, then, paves a middle way for those looking for a substance view of living organisms sensitive to the concerns raised by contemporary processualist philosophers of biology.

"Thomas Aquinas on the Metaphysical Structure of Artifacts", Vivarium, Vol. 61, No. 2 (Jun., 2023): pp. 141-166. [Published Version]

Abstract. It is now standard to interpret Aquinas as recognizing two main types of material objects: substances and artifacts, where substances are those material objects that result from some particular substantial form inhering in prime matter, and artifacts are those material objects that result from some particular accidental form inhering in one or more material substances. There are two problems with this standard interpretation. First, there are passages in which Aquinas states that accidental forms should be understood not as inhering in substances from the outside, but as entering into their composition so as to be included among their metaphysical parts. Second, there are passages in which Aquinas states that it is impossible for any accidental form to be shared by two or more substances. In this paper, I consider what implications these two observations might have for how we understand the metaphysical structure of artifacts in Aquinas’s ontology.

"Personal Identity, Sexual Difference, and the Metaphysics of Gender", Christian Bioethics, Vol. 29, No. 1 (Mar., 2023): pp. 77-94. [Published Version]

Abstract. Issues pertaining to sex and gender continue to be some of the most hotly debated topics of our time. While many of the most heated disputes occur at the level of politics and public policy, metaphysics too has a crucial role to play in these debates. In this essay, I explore several key metaphysical debates concerning sex and gender through the lenses of two important areas in contemporary metaphysics: the metaphysics of essence and the ontology of the human person. The goal here is not to advocate any particular position on these issues, but to show how the tools of contemporary metaphysics can help to offer a more comprehensive map of the conceptual terrain, indicating where major areas of agreement can be found and where the most important disagreements really lie.

"Are Christians Theologically Committed to a Rejection of the Principle of Alternative Possibilities?", The Heythrop Journal, Vol. 64, No. 1 (Jan., 2023): pp. 99-110. [Published Version]

Abstract. Many philosophers think that free will requires alternative possibilities. Other philosophers deny this. There are plenty of philosophical arguments on both sides of this debate, but here I want to highlight various theological pressures that might push Christians into rejecting the principle of alternative possibilities. In this paper, I explore six cases that might push Christians in that direction: the case of divine foreknowledge, the case of prophecy, the case of the blessed in heaven, the case of Christ’s human freedom, the case of Mary’s fiat in light of her immaculate conception, and the case of prayers for the past. As I will argue, in each of these cases, given certain other standard theological commitments, it seems that Christians are pushed to admit that the agent in question does indeed act freely but also that he or she did not possess alternative possibilities at the moment of decision.

"Thomas Aquinas and the Complex Simplicity of the Rational Soul", European Journal of Philosophy, Vol. 29, No. 4 (Dec., 2021): pp. 900-917. [Published Version]

Abstract. Thomas Aquinas holds that the rational soul is, like other created immaterial substances, both mereologically simple, in that it is completely lacking in any kind of material parts, but also mereologically complex, in that it includes within its composition its own essence, an act of existence, and various powers. Aquinas’s account of the mereological complexity of the rational soul introduces several complications for his understanding of the soul as the substantial form of the body and his larger ontology of the human person. After providing an overview of several key mereological notions operative in Aquinas’s thought, and an overview of the mereological simplicity and mereological complexity of immaterial substances in his ontology, I introduce three potential concerns for the Thomistic account, all of which might have been avoided had Aquinas instead understood the rational soul to be entirely mereologically simple – serving as the source and subject of, but bearing some other non-mereological relation to, the aforementioned parts. Though Aquinas does not pursue this simpler solution, I argue that he already has built into his ontology the resources to make such a solution consistent with the rest of his thought.

"From Potency to Act: Hyloenergeism", Synthese, Vol. 198, No. 11 (Jun., 2021) [Special Issue on “Form, Structure, and Hylomorphism”]: pp. 2691-2716. [Published Version]

Abstract. Many contemporary proponents of hylomorphism endorse a version of hylomorphism according to which the form of a material object is a certain kind of complex relation or structure. Structural approaches to form, however, seem not to capture form’s traditional role as the guarantor of diachronic identity, since more “dynamically complex” material objects, such as living organisms, seem to undergo, and survive, various structural changes over the course of their existence. As a result, some contemporary hylomorphists have looked to alternative, non-structural approaches to form. One of the leading non-structural approaches is the powers approach, according to which the form of a material object is a certain kind of power continuously activated in the object or in its material parts. In this paper, I begin by offering an overview and assessment of this powers approach to form. I argue that while the powers approach captures some crucial elements for understanding the nature of more dynamically complex material objects, when we press on the details of the view we find that it actually points to a related, but importantly distinct, third approach to understanding form, according to which the form of a material object is a certain kind of activity or process in which the material object or its parts are continuously engaged. I call this third approach “Hyloenergeism”. In the second half of the paper, I consider what such a view of material objects might look like and what its principal virtues might be.

"Not Just a Terminological Difference: Cartesian Substance Dualism vs Thomistic Hylomorphism", Roczniki Filozoficzne, Vol. 69, No. 1 (Mar., 2021) [Special Symposium on Richard Swinburne’s Are We Bodies or Souls?]: pp. 103-117. [Published Version]

Abstract. In Are We Bodies or Souls? Richard Swinburne presents an updated formulation and defense of his dualist theory of the human person. On this theory, human persons are compound substances, composed of both bodies and souls. The soul is the only essential component of the human person, however, and so each of us could, in principle, continue to exist without our bodies, composed of nothing more than our souls. As Swinburne himself points out, his theory of the human person shares many similarities with the hylomorphic theory of the human person espoused by Thomas Aquinas. Swinburne suggests at one point that the differences between the two theories are “almost entirely terminological”, pertaining chiefly to how each understands the term ‘substance’.  In this essay, I aim to show that the differences between Swinburne’s Cartesian substance dualism and Thomistic hylomorphism are much more significant than that. I argue, moreover, that the distinctive claims of Thomistic hylomorphism allow it to successfully avoid some key concerns for Swinburne’s view.

(with Dominic Mangino) "Should Animalists be 'Transplanimalists'?", Axiomathes, Vol. 31, No. 1 (Feb., 2021): pp. 105-124. [Published Version]

Abstract. Animalism, the view that human persons are human animals in the most straightforward, non-derivative sense, is typically taken to conflict with the intuition that a human person would follow her functioning cerebrum were it to be transplanted into another living human body. Some animalists, however, have recently called into question the incompatibility between animalism and this “Transplant Intuition,” arguing that a human animal would be relocated with her transplanted cerebrum. In this paper, we consider the prospects for this cerebrum transplant-compatible variant of animalism, which we call “Transplanimalism.” After presenting its account of three related thought experiments, and outlining its key advantages over Standard Animalism, we raise two concerns for Transplanimalism. First, we argue that Transplanimalism, like other closest-continuer accounts of the human person, encounters difficulties with symmetrical fission cases. Second, we introduce a new thought experiment that pushes Transplanimalism into surprisingly counterintuitive results. As a result of these concerns, we conclude that, despite its attractiveness, animalists should not endorse Transplanimalism.

"Causal Time Loops and the Immaculate Conception", Journal of Analytic Theology, Vol. 8 (Aug., 2020): pp. 321-343. [Published Version]

Abstract. The doctrine of the immaculate conception, which is a dogma binding on all Roman Catholics and also held by members of some other Christian denominations, holds that Mary the mother of Jesus Christ was conceived without the stain of original sin as a result of the redeeming effects of Christ’s later life, passion, death, and resurrection. In this paper I argue first that, even on an orthodox reading of this doctrine, the immaculate conception seems to result in a kind of causal time loop. I then consider several common philosophical objections to causal time loops, showing how each is either not a serious problem for causal time loops in general or is not a serious problem for the immaculate conception time loop in particular because of some particular features of that particular loop. The upshot of this discussion is that it shows that anyone who is committed to the dogma of the immaculate conception is also committed to the possibility, and, indeed, the actuality, of at least one causal time loop, but also that this is no reason to reject the dogma, since all of the major worries for causal time loops can be resolved in one way or another.

"Editor's Introduction", Quaestiones Disputatae, Vol. 10, No. 2 (Spring 2020) [Special Issue on “Hylomorphism: Ancient, Medieval, and Contemporary Approaches”]: pp. 5-27. [Published Version]

Abstract. Hylomorphism is the theory according to which the entities within a specified domain are best understood as composed of both matter and form. Contemporary discussions of hylomorphism have found philosophers revisiting classic points of contention concerning the theory’s scope, application, and utility, but it has also led philosophers to carefully reconsider how best to understand hylomorphism’s most basic claims. In this introduction, I begin by providing a brief overview of some of these main points of discussion in the contemporary literature on hylomorphism and some of the main hylomorphic views currently on offer. After that, I provide an overview of some of the main topics discussed in this special issue, offering a brief summary of each contribution.

"Accidental Forms as Metaphysical Parts of Material Substances in Aquinas's Ontology", Oxford Studies in Medieval Philosophy, Vol. 7 (Oct., 2019): pp. 67-114. [Published Version]

Abstract. Following in the hylomorphic tradition of Aristotle, Thomas Aquinas holds that all material substances are composed of matter and form. Like Aristotle, Aquinas also recognizes two different types of forms that material substances can be said to possess: substantial forms and accidental forms. Of which form or forms, then, are material substances composed? In this paper, I explore two competing models of Aquinas’s ontology of material substances, which diverge on precisely this issue. According to what I will refer to as the “Standard Model”, Aquinas’s view is that a material substance is composed of prime matter and substantial form. According to what I will refer to as the “Expanded Model”, Aquinas’s view is that a material substance is composed of prime matter, substantial form, and all of its accidental forms. After outlining the main claims of each of the two competing models, and considering two arguments in favor of the Standard Model, I offer two arguments in favor of the Expanded Model. I argue that, given the way in which he argues for God’s simplicity in question three of the Prima pars, and the way in which he consistently describes the difference between an essence and a suppositum, or individual substance, throughout his works, there is good reason to believe that Aquinas thinks that the accidental forms of a material substance are included among its metaphysical parts.

"Existential Import and the Contingent Necessity of Descartes's Eternal Truths", International Philosophical Quarterly, Vol. 59, No. 3, Issue 235 (Sep., 2019): pp. 309-319. [Published Version]

Abstract. Descartes famously sets aside certain mathematical and logical truths as comprising an important category known as the “eternal truths”. Descartes regards these truths as, in some sense, necessary, but he also famously claims that God could have made the eternal truths that are now in place false. This latter claim has led scholars to attribute to Descartes’ God a radical sort of power: the power to do the logically impossible. The purpose of this paper is to offer an interpretation of Descartes’ doctrine of the eternal truths that avoids attributing to his God this sort of power. Descartes does claim that God could have made any of the eternal truths that are now in place false. But I do not think that this commits him to the view that God could have made twice four equal to nine, or anything of that sort. In what follows, I show how, by placing Descartes’ doctrine of the eternal truths in its proper historical context, a new, more charitable interpretation of that doctrine becomes available, according to which Descartes’ God could have made the eternal truths false by choosing not to create the eternal essences to which these truths refer.

"Complex Survivalism, or: How to Lose Your Essence and Live to Tell About It", Proceedings of the American Catholic Philosophical Association, Vol. 91 (2017): pp. 185-199. [Published Version]

Abstract. Among those who defend a Thomistic, hylomorphic account of human persons, "survivalists" hold that the persistence of the human person's rational soul between death and the resurrection is sufficient to maintain the persistence of the human person herself throughout that interim. ("Corruptionists" deny this.) According to survivalists, at death, and until the resurrection, a human person comes to be temporarily composed of, but not identical to, her rational soul. One of the major objections to survivalism is that it is committed to a rejection of a widely-accepted mereological principle called the weak-supplementation principle, according to which any composite whole must, at every moment of its existence, possess more than one proper part. In this paper, I argue that by recognizing the existence of certain other metaphysical parts of a human person beyond her prime matter and her rational soul, hylomorphists can adhere to survivalism without violating the weak-supplementation principle. In order to make this solution work, however, survivalists may have to accept the claim that a human person can outlive her own essence.

"Three Concerns for Structural Hylomorphism", Analytic Philosophy, Vol. 58, No. 4 (Dec., 2017): pp. 360-408. [Published Version]

Abstract. Many contemporary proponents of hylomorphism, the view that at least some material objects are comprised of both matter and form, endorse a version of hylomorphism according to which the form of a material object is a certain complex relation or structure. In this paper, I introduce three sorts of concerns for this “structural" approach. First, I argue that, in countenancing an abundance of overlapping yet numerically distinct material objects, "structural hylomorphists" are committed to a certain sort of systematic causal overdetermination. Second, I argue that, because of its relatively thin conception of form, the view risks collapsing into some already well-entrenched metaphysical account of material objects. Finally, I argue that because the view emphasizes the more static structural features of composite material objects, structural hylomorphists seem unable to explain how it is that those objects might be said to persist over time through changes in such features.

"Hylomorphism and the Priority Principle", Metaphysica, Vol. 18, No. 2 (Sep., 2017): pp. 207-230. [Published Version]

Abstract. According to Jeffrey Brower’s hylomorphic account of material substances, prime matter and substantial forms together compose material substances, and material substances and accidental forms together compose accidental unities. In a recent article, Andrew Bailey has argued that Brower's account has the counter-intuitive implication that no human person is ever the primary possessor, the primary thinker, of her own thoughts. In this paper, I consider various ways in which Brower might reply to this objection. I first consider several “invariant strategies”, solutions that do not require any significant alteration to Brower’s account. I argue that these strategies are unsuccessful. I then introduce two ways of modifying Brower's hylomorphic account of material substances so as to avoid Bailey’s objection. I argue that these “variant strategies” are successful, but they require that Brower significantly alter one or more of the main features of his account.

"A Better Solution to the General Problem of Creation", European Journal for Philosophy of Religion, Vol. 9, No. 1 (Spring 2017): pp. 147-162. [Published Version]

Abstract. Could God have chosen not to create? Or was it necessary that He create at least some universe or other (even if it was not necessary that He create any universe in particular)? It is often suggested that, since the state of affairs in which God creates a good universe is, in some relevant sense, better than the state of affairs in which He creates nothing at all, a perfectly good God would have to create at least that good universe. Making use of recent work by Christine Korsgaard on the relational nature of the good, I argue that the state of affairs in which God creates a good universe might not actually be better than the state of affairs in which God creates nothing at all, due to the fact that it is not better for anyone or anything in particular. If this turns out to be right, then even a perfectly good God would not be compelled to create a good universe. In such case, God could indeed have chosen not to create.

Popular Pieces:

“Love Thy Students”, Logos: A Journal of Catholic Thought and Culture (forthcoming).

“Is Faith Irrational? Thomas Aquinas’s Summa Contra Gentiles, Book I, Chapters 3-9”, Philosophy Teaching Library. 24 Apr. 2024.

“Objects and their Parts: The Problem of Material Composition”, 1,000 Word Philosophy. 18 Apr. 2024.

[Also in Turkish! https://veritasdergisi.com/2024/07/03/nesneler-ve-parcalari-materyal-kompozisyon-problemi-jeremy-skrzypek/]

“Form and Matter: Hylomorphism”, 1,000 Word Philosophy. 4 Dec. 2023. 

“Mind, Soul, or Body? What Are We?”, An Interview with Phil-Stuff on The Metaphysics of Personal Identity. 4 Sep. 2023. 

“Method in Metaphysics: Discovering the Fundamental Structure of Reality”, Prime Matters. 5 Mar. 2021.

Book Reviews:

“Shorter Notice of C. Stephen Layman, God: Eight Enduring Questions”, Theological Studies, Vol. 83, No. 4 (Dec., 2022): p. 651. [Published Version]

“Review of Gaven Kerr, OP, Aquinas’s Way to God: The Proof in De Ente et Essentia”, Religious Studies Review, Vol. 42, No. 4 (Dec., 2016): pp. 273-274. [Published Version]

“Review of Alexander R. Pruss, One Body: An Essay in Christian Sexual Ethics”, Catholic Social Science Review, Vol. 19 (2014): pp. 244-246. [Published Version]