Thomas Aquinas and the Real Distinction

by Thomas M. Cothran

Aquinas’ celebrated “invention” of the real distinction between existence and essence in created things has secured his place at a pivotal moment of intellectual history. For some, such as Etienne Gilson, this shows Aquinas’ greatness. For some Orthodox, however, Aquinas’ originality is but another sign of the West straying from the tradition of the Fathers. It may be the case that Aquinas was not as innovative as his admirers and detractors have supposed. Certainly, Aquinas was a synthetic thinker, drawing on Church Fathers in both East and West, and harmonizing Aristotle with deeply neo-Platonic themes. His doctrine of the distinction between essence and existence drew in various ways from thinkers as diverse as Boethius, Avicenna, William of Auverne, and Proclus.

The genealogies of ideas are often put to use in theological circles as covert forces in the wider battles over the substantive truth of doctrine. It is no real defense of an idea to say that Augustine or Aquinas advocated it, and that a notion may be rejected Athanasius or John Damascene or Gregory Palamas hardly constitutes a decisive objection. The real question is: is this doctrine true? And yet, the temptation to pick a date in history around which to organize the decline and fall of entire systems of ideas or to locate the origin of a viral outbreak of ideas inimical to the supposed unified Christian tradition often proves too strong to resist.

The vital question—at least in matters not defined as binding dogma—does not concern who held such an idea to be true, but rather the truth. That some doctor of the church professed a doctrine can recommend his or her arguments for our careful consideration. And should we choose to go our own way, we can do so circumspectly, in the knowledge that minds greater than ours having thought otherwise.

In the case of the real distinction, then, we have available to us the arguments of St. Thomas Aquinas, Duns Scotus, Giles of Rome, and Gregory Palamas. The matter may be decisively resolved on philosophical grounds. The question for this article, then, is whether creation might be distinguished from God on the grounds that in created things essence and existence really differ, while in God they do not. Although the question can be adequately considered without appeal to the Scriptures or dogmas of the Church, its solution has enormous consequences for theology. If God is metaphysically simple, then any real distinction between essence and energies in God may be ruled out. Again, of God is not subject to composition, he cannot change, as many theistic personalists suppose. This article makes the case that the real distinction is in fact demonstrable, with a view towards showing that those theological positions that deny it are untenable.

1. There Can Be No More Than One Subsistent Being

At least in the case of the things we typically experience, existence can be gained and lost. Trees die, stars collapse, lakes dry up. These things can remain in memory, having cognitional existence after losing their real existence. Moreover, the fact that we can understand what or who something is without knowing whether it really exists suggests that there is some distinction between essence and existence.

Supposing for the moment that in some things existence is somehow other than essence, we might ask what consequences follow from the supposition of something whose essence is existence. By existence we mean simply the act by which something is. Ordinarily this is conceptualized very loosely as an accident, as what a thing has that makes it be. Some things only have cognitive existence, such as perfect triangles or fictional characters. Others have real existence.

Considering an entity for whom existence is essential rather than accidental bears a similarity to certain Platonist streams of thought, in which some feature accidental in the things of this world is hypothesized as subsisting in a primary instance. We can at least see what it would mean to posit a “pure redness”, the form of redness subsisting in itself, in which all red things partake. The difference between Redness and red things is that the latter are subjects that have redness, while the former just is Redness.

When St. Thomas claims that God is being itself subsisting, he’s saying something analogous (while rejecting, of course, the notion that other accidental forms such as redness exist independently). Something that subjects are conceived to have, existence, is posited as existing not in a subject, but as a subject. And yet, Aquinas grants, we have much more difficulty conceptualizing subsistent existence than we do an independently existing redness. In fact, Aquinas thinks we simply cannot have an authentic concept of existence, even in the case of things.

Whereas we can experience red things and form a concept more or less of what redness is from these experiences, we do not know existence through conceptualization, but through judgment. This distinction is clear enough. I can know understand every concept in the phrase “there is a bear in the backyard”; judging it to be true or false is another matter. If I try to conceptualize existence, I cannot gain the same sort of comprehension of it as I can other things. I am left with the general notion of whatever actuality makes things be at all. Aquinas would largely accept Kant’s critique of the concept of existence.

Given that we could not (at least on this account of conceptualization and judgment) know what existence is, either in the things that participate existence or Existence Itself, what would logically follow from the proposition that existence does in fact subsist in itself? In the first place, there could only be one such Being. For what is simply other than existence is non-existence. Existence, considered as a subsistent nature, has nothing outside it. While Redness itself could be distinguished by Greenness itself due to one having some determination the other does not, the same could not distinguish two existences, for what is simply outside existence is non-existence simpliciter. One Existence cannot have something the other lacks, or that other is not Existence but something else, something whose opposite is not nothing at all.

We cannot, then, posit something in addition to existence, except by participation. Participation has a number of senses, and here we need only the logical sense. Something may be other than existence without being nothing if it merely takes part in existence, if it has a limited way of being. A sunflower, for instance, does not exhaust the possibilities of existence, but has it in a way proportional to itself. It is not existence, but has a share of existence.

2. All Composite Things Depend on Subsistent Being

Subsistent being can, then, be posited (though not comprehended). Have we any reason for believing that subsistent being is real, and not just a concept we create? Is it merely something projected by the human mind, and God something other than Being itself? The existence of subsistent being follows from the double character of existence as accidental in things, and as prior to things.

2.1. Existence as an Accident

That existence is an accident follows clearly enough from the fact that being can be a subject in at most one instance. The term “accident” has stricter and looser senses, and existence is an accident in the looser sense of simply not being what a thing is, but what a thing in some way has. This is involves no commitment to any particular view of essences as universals.

A brief word on the use of the term essence. An essence in the concrete is a real thing, what or who really exists. It can also be taken in varying degrees of abstraction. Abstracting from the particularities of a particular person, we might arrive at the notion of “human being.” This sort of abstraction does not positively exclude the individual features of a person. Yet we may abstract with precision (to use Aquinas’ vocabulary), meaning that we positively exclude the individuating features, intending only in things what is common to the class we have in mind. If we abstract with precision, we end up not with “human being”, but “human nature.” This is why we say “Ann is a human being”, but not “Ann is a human nature.” Essence, then, always means a thing, considered by various degrees and types of abstraction.

2.2. The Priority of Existence

Denominating existence an accident has a peculiar feel. Most accidents presuppose their subject. For one to run, one must first be, and be the sort of being that can run. The yellow of a sunflower presupposes in some way the sunflower first being there. Accidents are not, after all, separate things that adhere to a separate subject, they are typically determinations of a subject.

Yet existence cannot suppose a pre-existent subject to actuate. Without existence, a thing is nothing. Existence is what makes a thing be at all. It is prior (in the order of efficient causality, not of time) to the thing. To put it another way, an essence is at every moment dependent upon its existence to be, and therefore cannot cause itself to be, for a subject to cause anything requires it prior existence. Of course, existence cannot precede essence in time, for it is the existence of this essence we are after. But even for something that exists eternally, it depends on its existence to be, and it cannot cause this existence.

2.3. The Necessity of Subsistent Being

If existence is an accident prior in the causal order to a thing, it must have a cause other than the essence it makes be. There is no need to posit the principle of causality as an axiom here; rather, it follows as a conclusion from being’s accidentality and priority. If existence causes itself, it is self-sufficient, and, rather than being an accident, would exist in its own right. A thing’s existence must be caused, therefore by something else: either a composite of essence and existence, or else subsistent existence. In the case of every composite, the power to cause another depends upon it first being caused. If A and B are composite beings, positing B’s causing A to explain A’s existence is no explanation until B’s existence is explained, for B’s power to cause A depends entirely on B’s existing in the first place, and thus upon whatever causes B. This holds no matter how many composite beings are posited as causes: in the case of efficient causality, no composite being or set of composite beings (whether finite or infinite) can explain the existence of the thing one begins with. Instead of providing an explanation, the number of things that remain unexplained multiplies. At no point in the causal sequence can existence arise. Positing a set (finite or infinite) of composite beings while denying the existence of subsistent being is the logical equivalent of positing the existence of nothing at all.

To hypothesize a multiplicity of composite beings while denying the reality of an existence subsistent in itself logically entails the existence of nothing at all. Since it is impossible to deny that at least some things exist, it follows from the dependent character of composite existence that it depends for its existence on an existent which subsists in itself, whose nature simply is existence. And of these, as we have seen, there can only be one.

The doctrine of the real distinction, then, is that in all beings have subsistent being, existence is received and participated, and existence is thus an actuality to which the receiving subject stands in potency. Actuality and potentiality are really distinct, yet due to the accidental status of thingly existence, neither can exist apart from the other. And this is what is meant by the term “composite.” Subsistent being itself brings all other things into being, whether mediately or immediately. Moreover, no pre-existent prime matter or quantum vacuum could precede this grant of being, for anything, of whatever sort, is nothing at all without its existence. The name “Creator” belongs properly to subsistent being.

3. Theological Conclusions

Though the real distinction is demonstrable on philosophical grounds, the theological conclusions quickly become evident.

3.1. Divine Simplicity

In the first place, God cannot have real accidents. Because God’s nature is unrestricted being, it cannot be isolated as “over here” or “of this sort”, as opposed to “over there” or “of that sort. Things can be distinguished from God by virtue of their finite essences. Yet accidents are not, properly speaking, things. Any distinct accident is an actuality of a subject, and the subject is in potency to the accident. Or to put it another way, an accident is a determinate way a subject can be. There is no perfection God lacks by his nature that would be added by a distinct accident. Subjects are, after all, the material for accidental forms, the underlying substratum that stands in potency to an accidental form. Accidents actualize the potential of a substance to be a certain way. Yet God, as pure existence—act superior to the act of form—cannot be in potency to anything.

3.2. Divine Perfections

If God is pure existence, there is no perfection God lacks. What is simply outside existence is nothing; thus all perfections that beings have are contained in some way within God. Finite things and their perfections cannot be simply other or outside God, and so they can be distinguished from God as having some share of being. On the hypothesis that we cannot conceptualize existence, and thus cannot comprehend God, we have no direct insight into how God possesses perfections. But the knowledge that God is subsistent existence (which is not the knowledge of what existence is, or what God is) requires of us that we affirm that God possesses all perfections, and even something about the mode in which these perfections are present in God.

Certain perfections are perfections in a qualified sense. Health is a perfection of a living thing, but entails the possession of a body that can become sick. Bodies, being material, can be destroyed, and being corporeal are limited to particular places at particular times. Health considered as a perfection includes also within itself imperfection, even relative non-being, and therefore cannot be literally ascribed to God. They are possessed virtually by God, and are the distinctive perfections that they are by virtue of their mixture with imperfection.

Unqualified perfections are in God eminently. While health, for instance, cannot literally be ascribed to God, life—in the sense of operating of oneself—can be so ascribed. God acts of himself, and is not affected by other things acting upon him. Yet life is not a distinctive property of God, as though in God life were one thing distinct from God’s other properties and God himself. If God had distinctive properties, he would be finite; his properties would improve upon his nature.

How is it possible to attribute to God justice, mercy, free will, power, life, and love, meaning by them different things, and yet recognize that in God there is no distinction between them? Nothing in the notion of life as operating of oneself entails any metaphysical composition or finitude. The way that God makes the statement true differs, of course, from the way we make the statement true. We are mammals, and have an animal life. Our form of life develops over time as we act and are acted upon. God makes the statement true in the opposite way: God is act, pure act, and is not subject to being acted upon by others. Both human beings and God make the predication of “life” true in their own respective modes—the one finite, imperfect, restricted; the other infinite, perfect, and unrestricted. And although we may perhaps have a good understanding of what living is like for finite beings, we cannot comprehend what God’s life is like. We know that God is infinite life, life in a more proper sense than we can claim, but what that life is like is revealed only indirectly, and is for us mediated through the order of finitude. Our access to it is mediated by the forms of life we can see and engage in ourselves. Thus, although our notions of life, justice, mercy, goodness, and love each differ from the other, this conceptual difference—that is, the differences that hold between our concepts—does not entail a real difference in God between his properties, nor does it prevent literal speech about God.

4. Conclusion

The argument for the real distinction is no relic from the Middle Ages, nor a sectarian doctrine confined to Roman Catholicism. It is a truth capable of strict demonstration. Its consequences reverberate throughout the metaphysical arguments for God’s existence, and have far-reaching implications for theology. It establishes not only the demarcation between God and the gods (and us), but also rules out any theological position that would make God into a finite spirit—as in many analytic circles—or that would posit distinctive faculties in God. It both establishes God as beyond our powers of comprehension and simultaneously shows how all of creation imitates and participates in him. And for that reason it is catholic, not Roman Catholic.

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Thomas Cothran is a writer and lives in Lexington, Kentucky. He blogs at Interstices Between Philosophy and Theology

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5 Responses to Thomas Aquinas and the Real Distinction

  1. stmichael71 says:

    I just would want to add, as a completely orthogonal point, that there seems to be nothing in such a view that would require one to reject some kinds of distinction between God’s essence and energies. It is that distinction that Orthodox theologians fear is lost in affirming the Thomistic theory of divine simplicity.


    • Fr Aidan Kimel says:

      Thanks for raising this point. It’s unclear to me also how Thomas’s affirmation of the identity of the divine essence and divine existence impacts the Byzantine distinction, especially given the way this distinction was modified after St Gregory Palamas.


  2. Thomas says:

    I agree that divine simplicity doesn’t rule out all distinctions, even real distinctions, in God. While some formulations of the energies/essence distinction would be excluded–for instance, that God’s energies are operations, intrinsic acts, or faculties–it is certainly not evident to me that all formulation would be excluded.

    However, it is difficult for me to see how they could be reconciled. Many Orthodox theologians do regard the essence-energies distinction to be incompatible with divine simplicity (e.g., David Bradshaw, Christos Yannaras, George C. Papademetriou). So while the energies-essence distinction has been articulated in ways that deny that God is essentially pure act, I’ve not seen it clearly articulated in a way that is compatible with God as actus purus. If the distinction is a conceptual one, they would be compatible. I’d be interested in other attempts to reconcile the two, if you know of any.


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