The notion of essential predication is connected to what are traditionally called the categories (katêgoriai).
In a word, Aristotle is famous for having held a “doctrine of categories”.
Just what that doctrine was, and indeed just what a category is, are considerably more vexing questions.
They also quickly take us outside his logic and into his metaphysics.
Here, I will try to give a very general overview, beginning with the somewhat simpler question “What categories are there?”
We can answer this question by listing the categories.
Here are two passages containing such lists:
We should distinguish the kinds of predication (ta genê tôn katêgoriôn) in which the four predications mentioned are found. These are ten in number: what-it-is, quantity, quality, relative, where, when, being-in-a-position, having, doing, undergoing. An accident, a genus, a peculiar property and a definition will always be in one of these categories. (Topics I.9, 103b20-25)
Of things said without any combination, each signifies either substance or quantity or quality or a relative or where or when or being-in-a-position or having or doing or undergoing.
To give a rough idea, examples of substance are man, horse; of quantity: four-foot, five-foot; of quality: white, literate; of a relative: double, half, larger; of where: in the Lyceum, in the market-place; of when: yesterday, last year; of being-in-a-position: is-lying, is-sitting; of having: has-shoes-on, has-armor-on; of doing: cutting, burning; of undergoing: being-cut, being-burned. (Categories 4, 1b25-2a4, tr. Ackrill, slightly modified)
These two passages give ten-item lists, identical except for their first members.
What are they lists of?
Here are three ways they might be interpreted:
– The word “category” (katêgoria) means “predication”.
Aristotle holds that predications and predicates can be grouped into several largest “kinds of predication” (genê tôn katêgoriôn).
He refers to this classification frequently, often calling the “kinds of predication” simply “the predications”, and this (by way of Latin) leads to our word “category”.
– First, the categories may be kinds of predicate: predicates (or, more precisely, predicate expressions) can be divided into ten separate classes, with each expression belonging to just one class.
This comports well with the root meaning of the word katêgoria (“predication”).
On this interpretation, the categories arise out of considering the most general types of question that can be asked about something:
“What is it?”; “How much is it?”; “What sort is it?”; “Where is it?”; “What is it doing?”
Answers appropriate to one of these questions are nonsensical in response to another (“When is it?” “A horse”).
Thus, the categories may rule out certain kinds of question as ill-formed or confused.
This plays an important role in Aristotle’s metaphysics.
– Second, the categories may be seen as classifications of predications, that is, kinds of relation that may hold between the predicate and the subject of a predication.
To say of Socrates that he is human is to say what he is, whereas to say that he is literate is not to say what he is but rather to give a quality that he has.
For Aristotle, the relation of predicate to subject in these two sentences is quite different (in this respect he differs both from Plato and from modern logicians).
The categories may be interpreted as ten different ways in which a predicate may be related to its subject.
This last division has importance for Aristotle’s logic as well as his metaphysics.
– Third, the categories may be seen as kinds of entity, as highest genera or kinds of thing that are.
A given thing can be classified under a series of progressively wider genera:
– Socrates is a human, a mammal, an animal, a living being.
The categories are the highest such genera.
Each falls under no other genus, and each is completely separate from the others.
This distinction is of critical importance to Aristotle’s metaphysics.
Which of these interpretations fits best with the two passages above?
The answer appears to be different in the two cases.
This is most evident if we take note of point in which they differ:
– the Categories lists substance (ousia) in first place, while the Topics list what-it-is (ti esti).
A substance, for Aristotle, is a type of entity, suggesting that the Categories list is a list of types of entity.
On the other hand, the expression “what-it-is” suggests most strongly a type of predication.
Indeed, the Topics confirms this by telling us that we can “say what it is” of an entity falling under any of the categories:
– an expression signifying what-it-is will sometimes signify a substance, sometimes a quantity, sometimes a quality, and sometimes one of the other categories.
As Aristotle explains, if I say that Socrates is a man, then I have said what Socrates is and signified a substance; if I say that white is a color, then I have said what white is and signified a quality; if I say that some length is a foot long, then I have said what it is and signified a quantity; and so on for the other categories.
What-it-is, then, here designates a kind of predication, not a kind of entity.
This might lead us to conclude that the categories in the Topics are only to be interpreted as kinds of predicate or predication, those in the Categories as kinds of being.
Even so, we would still want to ask what the relationship is between these two nearly-identical lists of terms, given these distinct interpretations.
However, the situation is much more complicated.
First, there are dozens of other passages in which the categories appear.
Nowhere else do we find a list of ten, but we do find shorter lists containing eight, or six, or five, or four of them (with substance/what-it-is, quality, quantity, and relative the most common).
Aristotle describes what these lists are lists of in different ways:
– they tell us “how being is divided”, or “how many ways being is said”, or “the figures of predication” (ta schêmata tês katêgorias).
The designation of the first category also varies:
– we find not only “substance” and “what it is” but also the expressions “this” or “the this” (tode ti, to tode, to ti).
These latter expressions are closely associated with, but not synonymous with, substance.
He even combines the latter with “what-it-is” (Metaphysics Z 1, 1028a10: “… one sense signifies what it is and the this, one signifies quality …”).
Moreover, substances are for Aristotle fundamental for predication as well as metaphysically fundamental.
He tells us that everything that exists exists because substances exist:
if there were no substances, there would not be anything else.
He also conceives of predication as reflecting a metaphysical relationship (or perhaps more than one, depending on the type of predication).
The sentence “Socrates is pale” gets its truth from a state of affairs consisting of a substance (Socrates) and a quality (whiteness) which is in that substance.
At this point we have gone far outside the realm of Aristotle’s logic into his metaphysics, the fundamental question of which, according to Aristotle, is “What is a substance?”.
See Frede 1981, Ebert 1985 for additional discussion of Aristotle’s lists of categories.
For convenience of reference, I include a table of the categories, along with Aristotle’s examples and the traditional names often used for them.
For reasons explained above, I have treated the first item in the list quite differently, since an example of a substance and an example of a what-it-is are necessarily (as one might put it) in different categories.
Traditional name Literally Greek Examples
(Substance) substance “this” what-it-is ousia tode ti ti esti man, horse Socrates “Socrates is a man”
Quantity How much poson four-foot, five-foot
Quality What sort poion white, literate
Relation related to what pros ti double, half, greater
Location Where pou in the Lyceum, in the marketplace
Time when pote yesterday, last year
Position being situated keisthai lies, sits
Habit having, possession echein is shod, is armed
Action doing poiein cuts, burns
Passion undergoing paschein is cut, is burned