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Current Theology Thoughts: Pt. 2, Definitions

I started this post just reviewing patristic quotes of immutability, but as I’ve thought through the idea, I think that I need to review definitions of some basic words used in theology and philosophy, and really think through some implications. I’ve decided this post should be split into multiple posts. I should probably also re-write a lot of this and try to publish it somewhere, and actually make some income off of my thoughts [which, if you do think this deserves some level of monetary support, please do donate!!]. Regardless–

Right now, I’m debating a number of theological issues, just sort of mulling them over in my head. Of primary interest to me are the doctrines of God’s incomprehensibility and immutability. These suggest certain things about our conception of His “decrees” (as discussed in Reformed thought), about archetypal-ectypal theology, about the ontological-economical distinction, and other such distinctions within theological discussions. And I’m unsure about what these theological concepts mean for some very basic theology, such as justification, satisfaction-atonement, and even the incarnation. For example, if God is immutable, that is, unchanging in His being, then what can it mean for one to pass from a state of being in His favor, to passing to a state of being in His disfavor, or else vice-versa? If He cannot change in His disposition, since He does not change in His being, then how can He change in being displeased to being pleased? Similar is the issue of the atonement. In the classic Protestant (and Romanist) conception of satisfaction theory, God goes from being displeased to pleased with His Son. If sin is imputed to one, and God’s disposition changes, and sin is appeased in one, and God’s disposition changes, then again, this entails a change of God’s being.


A thought that I don’t find troubling so much, but more interesting, is what the incomprehensibility of God means as it relates to philosophical-theological definitions. For example, when one says God is incomprehensible as to His essence, what this implies is that God may be comprehensible as to other things, such as His hypostases (Persons), or as to His attributes (including, ironically, incomprehensibility), or his existence, or nature, or properties, etc. And so if I really want to know in what way God can be comprehended, and in what way He cannot, I really have to examine definitions of fundamentals.

Most of these definitions carry over into theological discussion from either Platonism/neo-Platonism or a modified form of Aristotelianism. In current discussions in theology, most theologians have adapted or adopted elements of these, though I find in their writings a piecemeal usage of the terms and definitions based off of one group or the other.

Defining a property (predication, universal)

I want to look at this first because without properties, or distinctions, or universals, discussion about reality is impossible. A property is a predication, or something that can be attributed to something else. For example “big” is a property. Properties are generally understood as being universals, or things that can be instantiated or shared by other things. For transcendent realists like Plato, these universals are transcendent entities he called ‘forms’ or ‘ideas’. For immanent realists like Aristotle, universals exist only (but truly) in instantiated things. For nominalists, universals do not exist outside of the human mind. Instead, universals are something done by the linguistic act in predication and/or in tropes. Conceptualists agree with nominalists, but rather than proposing tropes as a solution, they argue that ‘concepts’ are what we utilize to band together items that appear similar to us.1

Next, I want to look at the definitions of the terms being, essence, substance, and form. These all seem, on surface level, to be very different. But many early philosophers use the terms being, essence, substance, and form somewhat interchangeably. At the same time, some early philosophers do distinguish them (sort of), and later philosophers and theologians certainly distinguish them.

Defining existence/being (existentia, οὐσία, a thing that is)

Avicenna, Aquinas, and Boethius all say that ousia, a Greek term typically translated as “being”, means the same thing as essentia, a Latin term typically translated as “essence”. I would summarize it as meaning “a thing that exists in some manner” (ie whether real or imagined).

But, Aquinas also argues that essentia can be understood in another way, in which essentia means quidditas (quiddity or essence) rather than mere existence or being.2 3

There may be other philosophers who parse ousia out from essentia, and if so, I’d be interested to receive some comments about it for further reading.4

Defining essence (essentia, τὸ τί ἦν εἶναι, τὸ τί ἐστι, ὁρισμός, quidditas, haeccitaes, ontic, a thing in res )

Philosophers differ on this somewhat, but a basic explanation is that essence is the base “thing” that makes something what it is.

“‘Essence’ is the standard English translation of Aristotle’s curious phrase to ti ên einai, literally “the what it was to be” for a thing. This phrase so boggled his Roman translators that they coined the word essentia to render the entire phrase, and it is from this Latin word that ours derives. Aristotle also sometimes uses the shorter phrase to ti esti, literally “the what it is,” for approximately the same idea.” 5

For a comparison of differing views of essence, as well as its historical development, just check out Wikipedia. I’m literally just pasting it’s summary below:

In his dialogues Plato suggests that concrete beings acquire their essence through their relations to “Forms”—abstract universals logically or ontologically separate from the objects of sense perception. These Forms are often put forth as the models or paradigms of which sensible things are “copies”. When used in this sense, the word form is often capitalized.[7] Sensible bodies are in constant flux and imperfect and hence, by Plato’s reckoning, less real than the Forms which are eternal, unchanging and complete. Typical examples of Forms given by Plato are largeness, smallness, equality, unity, goodness, beauty and justice.

Aristotle moves the Forms of Plato to the nucleus of the individual thing, which is called ousia or substance. Essence is the ti of the thing, the to ti en einai. Essence corresponds to the ousia’s definition; essence is a real and physical aspect of the ousia (Aristotle, Metaphysics, I).

According to nominalists (Roscelin of Compiègne, William of Ockham, Bernard of Chartres), universals aren’t concrete entities, just voice’s sounds; there are only individuals: “nam cum habeat eorum sententia nihil esse praeter individuum […]” (Roscelin, De gener. et spec., 524). Universals are words that can call to several individuals; for example the word “homo”. Therefore, a universal is reduced to a sound’s emission (Roscelin, De generibus et speciebus).

John Locke distinguished between “real essences” and “nominal essences”. Real essences are the thing(s) that makes a thing a thing, whereas nominal essences are our conception of what makes a thing a thing.[8]

One thing of note–it’s been a regular facet of philosophy/theology to parse out how essences relate to the words we use about things. It’s worth noticing that though Locke makes that distinction between real and nominal essences, even in the late Middle Ages, Aquinas proposes a distinction between real essences and linguistic terms that don’t refer to real things. He suggests this in his work on ‘Being’, in points 3-6, which was written far prior to Locke, and also written during the nominalist philosophy/theology. Following Avicenna, he argues that the term ‘being’ can have two meanings, referring either to real entities or non-real concepts, but that the term ‘essence’ always relates to the first usage of ‘being’ (real entities).6

Defining a substance (οὐσία, substantia, substratum )7

From what reading I’ve done, I think Plato’s works refer to substance and essence interchangeably, utilizing the term ousia. For this reason, the definition of a substance, for Plato, is the same as that of his definition of essence. Similarly, for Aristotle, substance is primarily defined as the fundamental essence or nature of a thing that makes it what it is. “Aristotle’s preliminary answer (Ζ.4) to the question ‘What is substance?’ is that substance is essence”.8 In Ricouer’s interpretation of Aristotle, he argues

“His [Aristotle’s] philosophy of ousia, of beingness, of étance, oscillates between a Platonic philosophy of the Form and an empiricist philosophy of the concrete understood as an ‘act’ mixed with potentiality” (p. 236). This explains why ousia is both (and has been translated as) substance and essence. It is a “de-existentialized ousia” (p. 249).

Pol Vandevelde, quoting Ricouer in his review of Being, Essence and Substance in Plato and Aristotle9

Within Aristotle’s work he distinguished between two types of substances: primary substances (also called specific or particular substances), which are individual entities (e.g., a particular human, a specific tree), and secondary substances (also called universal substances), which are the universal categories or classes that these individual entities belong to (e.g., human beings, trees). According to Aristotle, substance is not separate from the material.

“Universal [secondary] substances are those things that are predicated quae genera or species…and can be equally predicated of each of the individuals that make up the species or genus” says this summary of Boethius. For example, “red” is a universal substance that can be equally predicated of many individuals. Specific/particular [primary] substances are those that can only be predicated of particular things.

Defining a form

For Plato, forms are universals that are transcendent entities. Earthly physical forms are copies or imitations of these transcendent forms. In Aristotle’s explanation, all physical items are a compound of matter and form (hylomorphism).10

“A thing’s form is its definition or essence—what it is to be a human being, for example. A statue may be human-shaped, but it is not a human, because it cannot perform the functions characteristic of humans: thinking, perceiving, moving, desiring, eating and growing, etc. The connection between a thing’s form and its function emerges in Physics ii 3, where Aristotle distinguishes his four kinds of cause: material, formal, efficient, and final, and suggests a special connection between the formal and final cause.”11

In the Aristotelian view, form is not a transcendent element, existing in a world of ideas. Instead, forms are intimately related to material.

“A substantial form is the essence of a substance, and it corresponds to a species. Since it is an essence, a substantial form is what is denoted by the definiens of a definition. Since only universals are definable, substantial forms are universals. “12

A potential issue with this idea is how to account for the existence of so many substantial forms. One suggestion is that Aristotle might have propounded something called prime matter.

 “The traditional interpretation of Aristotle, which goes back as far as Augustine (De Genesi contra Manichaeos i 5–7) and Simplicius (On Aristotle’s Physics i 7), and is accepted by Aquinas (De Principiis Naturae §13), holds that Aristotle believes in something called “prime matter”, which is the matter of the elements, where each element is, then, a compound of this matter and a form. This prime matter is usually described as pure potentiality, just as, on the form side, the unmoved movers are said by Aristotle to be pure actuality, form without any matter (Metaphysics xii 6). What it means to call prime matter “pure potentiality” is that it is capable of taking on any form whatsoever, and thus is completely without any essential properties of its own.”13

Ricouer argues (and critiques) that, for Aristotle, form displays or makes known a substance/essence but does not make known what the individual being is precisely:

Regarding individuation, Ricoeur shows that Aristotle’s understanding of reality as what is definite and determined does not amount to equating substance with an individual entity. A substance is knowable through its form, but the singular is “undetermined” (p. 234) for Aristotle, precisely to the extent that it is not universal and thus not fully intelligible. Aristotle, Ricoeur argues, manifests an “indifference to the singularity of individuals” (p. 148). As a consequence, what is most real in an individual is its essence and not so much its existence, for which, Ricoeur contends, Aristotle does not really have a theory. Rather, he “is driven back to the side of a philosophy of quiddity and not of the individual” (p. 234) and remains, like Plato, “a philosopher of intelligibility” (p. 148). 14

Defining a nature (natura, phusis),

Empedocles, a pre-Socratic philosopher, taught that ‘nature’ is both the primary matter and the form or essence. Aristotle argues that “Nature is an inner principle of change and being at rest.”15
Later, Boethius argues that nature is, “the specific difference that gives form to each thing” and, “the specific property of any substance.” Within this thought, some natures are substances (ie necessary for existence as a distinct entity) and other natures are accidents (ie unnecessary for existence as a distinct entity).

Aquinas distinguishes between nature and essence in his De ente et essentia.16 He argues that though Aristotle says every substance is a nature, by that phrase Aristotle really means “the essence of a real thing according as it has an ordering to the thing’s proper operation”, and that substance and nature (if defined differently) are not the same thing. Aquinas says that the term ‘quiddity’ is really what is used to define an essence, “But it is called essence from the fact that through it and in it a real being has existence.” He argues that in composite forms, an essence isn’t a third thing (matter + form = third thing called essence), but rather it is what gives a thing its matter and form.

Boethius is in agreement with this in his commentary on the Predicaments, where he says that ousia signifies the composite. For ousia in Greek is the same as essentia in Latin, as he himself says in his book On the Two Natures. Ibn-Sînâ, too, says that the quiddity of composed substances is the composition itself of form and matter. And the Commentator, likewise, in his considerations on the seventh book of the Metaphysics says: “The nature which species have in generable things is something in between, i.e., composed of matter and form.”

-Aquinas, De ente et essentia 19

Aquinas later distinguishes form from essence, saying, “The essence of a composed substance and that of a simple substance differ in this: the essence of a composed substance is not form alone, but includes form and matter; the essence of a simple substance is form alone.” -73

Ricouer provides a critique of Plato and Aristotle on these terms, because, in his opinion it creates

…the unstable status of being. In Plato it was, among other things, the ambivalence of the idea as what confers being on the sensible and as what is still in need of being. In Aristotle it is the tension between essence, which makes the individual intelligible, and existence, which gives individuation to the entity, but no intelligibility and thus no real ontological status.

Pol Vandevelde, summarizing Ricouer in his review of Being, Essence and Substance in Plato and Aristotle

I.e. a critique that could be leveled at Plato is to question what makes a sensible/visible entity a real being, or what makes the Forms into sensible entities. A critique that could be leveled at Aristotle is to ask what is the proper relationship between being (existentia/ousia) and essence (essentia).

Defining a person (persona, hypostasis)

The classic definition of a person is given by Boethius as, “An individual substance with a rational nature.” This comprises both the essentialist and the stipulative definitions of ‘person’. Similarly, Aquinas says, “Every individual of a rational nature is called a person.” His logic is spelled out here:

“If Person belongs to substances alone, and among these to rational ones, and if every substance has a nature, existing not in universals but in individuals, we have found the definition of Person, viz: the individual substance of a rational creature.”


The logic above is:

  • Every substance has a nature that exists in individuals and not universals.
  • Some substances are rational.
  • Person belongs to rational substances alone.
  • Therefore a Person is an individual substance of a rational creature.

Reviewing this logic, I think Ricouer’s critique of Aristotle (mentioned above) could be answered by pointing out the connection between a thing’s nature and a thing’s substance. While substance might not be individual, nature always is.

Read More:

Part 1, Part 3, Part 4

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  3. See this learned discussion on Reddit ↩︎
  4. For instance, Feser mentions the distinction between essence & existence in Thomas’ thought, but doesn’t parse out what that means entirely. See ↩︎
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  6. Aquinas, De ente et essentia ↩︎
  7. For an overview see ↩︎
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  16. Aquinas, De ente et essentia ↩︎


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