Theory and History of Ontology ( Raul Corazzon | e-mail:

The Doctrine of Categories from an Historical Perspective

Contents of this Section

Introduction to the History of the Doctrine of Categories


"Metaphysics, in its minimal form, is the activity of categorial description. Its subject matter is the most fundamental aspects of the way we think about and talk about reality, the most fundamental features of reality as it presents itself to us. We divide the world into horses and trains, people and mountains, battles and towns, and a whole complex structure of different kinds of things; our language is the repository of this enormously rich furnishing of the world. But we can discern within this richness some overall divisions, between things and their properties for example, or between events and the times and places in which they happen, and it is with the overall pattern of our categorising of elements of the world that metaphysics concerns itself. The basic divisions which our thought and talk about reality entail are the quarry of categorial describers.


Aristotle's categories are 'predicables' because (with reservations to be looked at later) they are things predicated of something: when we say, for example, that 'Socrates is a man' we are predicating being a man of Socrates, i.e. a certain kind of substance. Again, when we say that 'Aristotle is in the Lyceum', we are predicating being in the Lyceum of Aristotle, i.e. a certain place, physical location. The ten predicables listed are the ten kinds of things that can be said of something. Now 'thing' is used here intentionally to convey the fact that Aristotle is, in the first place, talking about the world and not about language. It is being in the Lyceum as such that is predicated or said of Aristotle, not the expression 'in the Lyceum' which is (if at all, and certainly in a different sense of 'said of') said of 'Aristotle' the name.

But 'thing' is used also to convey another fact about Aristotle's ten predicables, namely that the list involves a division into ten types or kinds of what can be variously called 'things', 'entities', 'existents' or 'beings'. Socrates is one kind of thing, a substance, and so is Aristotle; in-the-Lyceum is another kind of entity, a place or location; four-foot is a quantity; white is a quality; yesterday is a time; and so on. Aristotle, in drawing up a list of the ten different kinds of things predicable of something else, is drawing up a list of the ten different kinds of beings, entities, existents, or things. According to Aristotle we have to distinguish the categories of substance, place, time, quality, action and so on.

Now where does Aristotle get all this from, and is he right? (...)

How on earth could Aristotle have come up with this classification of things in existence in terms of ten categories? Clearly he did not engage in an empirical investigation of the things around him and arrive at his result as he would at a classification of species of animals or plants. The answer has to be that, insofar as the list is the product of investigation it was investigation of our thought and talk about the things which Aristotle could find around him. One commentator on Aristotle's list suggests that it was arrived at by distinguishing different questions which may be asked about something and noticing that ... only a limited range of answers can be appropriately given to any particular question. An answer to 'where?' could not serve as an answer to 'when?'. Greek has, as we have not, single-word interrogatives meaning 'of what quality?' and 'of what quantity?' ... and these, too, would normally collect answers from different ranges. (*)

Something along these lines has to be right, since Aristotle could not have investigated reality directly, and that for at least two reasons. One is that reality is not something which itself lies beyond or prior to our thought and talk about it in a way that allows of independent perusal, since reality is for us the very thing which our thought and talk concerns. If that looks tautological, let it be: a more substantial claim needs greater argument than I can offer now. The second reason is that any perusal of reality would need to rest upon a way of classifying what is discovered in it: are we going to list places and times, qualities and numbers, relations and events? Well, that depends on the categories involved in our thought and talk. It is the very result of category division in our thinking and talking that the world divides up as it does. A way of putting this point is in terms of perception. To perceive the world is not, as a naive Lockean might think, to passively notice what is there; it is to conceptualise and hence pigeonhole what is there. And categories are the broadest, most fundamental and most general of our pigeonholing devices." (pp. 2-4)


(*) J. L. Ackrill, Aristotle's Categories and De Interpretatione, Oxford: Oxford University Press 1963, p. 78.

From: Brian Carr, Metaphysics. An introduction, London: Macmillan 1987.