In the early fourth century the terms ousia and hypostasis were synonyms and virtually interchangeable in philosophical usage, yet by the end of the fourth century orthodox theologians were using them differently to speak of the one God who is Father, Son, and Holy Spirit. St Basil of Caesarea made the decisive linguistic move. As he wrote to Count Terintius: “If you ask me to state briefly my own view, I shall state that essence has the same relation to hypostasis as the common has to the particular” (Ep. 214). Following the line advanced by his brother, St Gregory of Nyssa’s To Peter on the Divine Ousia and Hypostasis represents an instructive and clarifying contribution to this development.
Gregory begins with an analysis of common nouns. Common nouns signify that common nature (ousia—typically translated “substance” or “essence”) shared by particular existents, i.e., that which qualifies the existents as belonging together in a class or genus. It tells us what something is. Consider, for example, the noun “man.” When we use this word, we do not denote individual human beings in their particular existence (i.e., to Andrew as opposed to John and James) but the common nature which makes Andrew, John, and James human beings instead of, say, giraffes or rocks. “The commonality of what is signified extends alike to all ranked under the same name,” explains Nyssen, “and requires some further distinction if we are to understand not ‘man’ in general, but Peter or John” (EpPet. 2a). By itself, the common nature denoted by a common noun is an abstraction. It does not exist by itself, as a some thing; it subsists only in specific things: that is to say, ousia is instantiated in individuals and otherwise has no independent existence. When we consider three specific human beings, such as Paul, Silvanus, and Timothy, “no-one will give one definition of substance for Paul, another for Silvanus, and yet another for Timothy. No, whatever the terms used to indicate the substance of Paul they will also apply these to the others, and they are consubstantial with one another who are designated by the same definition of substance” (EpPet. 2b). Note that individual human beings may be said to be consubstantial with each other, for they share in the same nature.
So far so good. It seems all straightforward and commonsensical. However Gregory understood the metaphysics of ousia, his grammatical analysis of common nouns is easily translated into the 21st century. We might next expect Gregory to contrast common nouns with proper nouns: if a common noun identifies the class to which an individual belongs, a proper noun identifies a specific individual within that class. If “man” identifies humanity as a whole, and thus the nature which all human beings possess, then “Paul,” “Silvanus,” and “Timothy” denote the three specific human beings who bear those names.
I found that in reading this letter I needed to temporarily put aside my understanding of proper names. Two decades ago I did a fair amount of research into the linguistics of proper names for an article Don Hook and I wrote on the divine title “Father.” What I learned back then (and, alas, have since forgotten) is that a proper name functions as a rigid designator: it denotes one specific entity, in contrast to a common noun, which denominates a class of entities. A proper name achieves its power of reference through a process of historical dubbing. At some point in history someone or someones assigned a specific existent its own special name; and this name was accepted, confirmed, and continued by subsequent usage. A proper noun, therefore, effectively refers independently of all identifying descriptions. I am known as “Alvin” because my parents named me “Alvin,” and I have been called by this name ever since. This construal of proper names, advanced by Saul Kripke, is known as the causalist theory.
When we hear St Gregory invoking “Paul,” “Silvanus,” and “Timothy,” we might be tempted, as I was, to think that he had something like this theory of proper nouns in mind; but a read-through of the letter indicates otherwise. Gregory appears to hold an early version of the description theory of proper names (at least I think he does). “The Description Theory of names (a.k.a. descriptivism),” explains the Stanford Encyclopedia of Philosophy, “says that each name N has the semantic value of some definite description ‘the F’.” A proper name signifies the various descriptions that together effectively identifies the referent and separates it from all other possible referents.
Other nouns have a more individual signification, in that what is contemplated in the thing is not the commonality of nature but a circumscription of a some reality, which, as far as its individuality goes, has no communion with what is of the same kind, as for example, Paul or Timothy. For such an expression no longer has reference to what is common in the nature, but by separating certain circumscribed conceptions from the general idea, expresses them by means of their names. (EpPet. 2b)
If a common noun refers to that nature which all members of a given class share, a proper noun refers to “the individual properties by which the one is distinguished from the other” (EpPet. 2c). While different members may possess some of the same properties, “the definition by which each is known will no longer tally in all particulars with the definition of another” (EpPet. 2c).
For Gregory, common noun is to ousia what proper noun is to hypostasis: “This therefore is the hypostasis: not the indefinite notion of the substance, which finds no instantiation because of the commonality of what is signified, but that conception which through the manifest individualities gives stability and circumscription in a certain object to the common and uncircumscribed” (EpPet. 3b).
Gregory gives an example from the Book of Job. When the narrator begins the story, he first identifies Job by means of substance, “There was a man …,” thus indicating the common nature that he shares with all men. The narrator then proceeds to individualize Job “by means of particular identifying notes, by mentioning the place and identifiable habits and such external marks that would distinguish him and mark him off from the common signification” (EpPet. 3c).
John Behr summarizes Gregory’s presentation thus far:
A term such as “man” can be applied to many objects and, therefore, denotes the common nature that they share. But the common element is an abstraction, indicating something general, an “indefinite concept.” This common element, the nature or the essence does not exist by itself; it is not a thing (πρᾶγμα), an entity, that actually exists. Nature or essence only subsists in particular entities denoted by particular names. Thus, the common element needs to be further delimited if it is to be “given-standing” as a subsisting being, if, that is, we are to understand not simply “man in general,” but specifically Peter or Paul. A term such as “man” indicates what kind of being something is, the ousia, while a particular name denotes a concrete, specific object (“thing,” πρᾶγμα), the ousia subsisting in a particular manner, delimited and denoted by the hypostasis. The term hypostasis, therefore, for Gregory, refers not so much to the particular entity itself (for which, at least in the created realm, he uses πρᾶγμα), but the particularizing properties by which it is made known. (The Nicene Faith, II:417).
Please note: for Gregory hypostasis signifies neither the abstract common nature shared by entities within a given class nor a specific entity independent of its descriptive characteristics. It signifies the concrete collection of differentiating notes and properties by which a particular subsistent is identified.
“Transpose then to the divine dogmas,” recommends Nyssen to his readers, “the same principle of differentiation which you acknowledge with regard to substance and hypostasis in our affairs, and you will not go wrong” (EpPet. 3e).