Aristotle started out by distinguishing between words and things.[5] He now connects them. We may use combinations of words to express connections of things. For instance, ‘Socrates is pale’ expresses a condition of Socrates. Further, ‘Socrates is a man’ explains what kind of thing he is. But notice, as Aristotle does, the difference in these two kinds of statements. The former describes a temporary condition of the subject; the latter tells what kind of thing he necessarily is. Call the first kind of assertion “accidental predication”; call the second “essential predication.” We now have two kind of connections between entities, one represented by the horizontal juxtaposition (accidental predication), and one by the vertical (essential predication). The former kind of assertion describes a temporary state or condition of the subject, the latter a necessary state, even a kind of definition.
What we have here in the ontological square is the representation of an ontology, a theory of the basic entities of the world. It is simple, elegant, suggestive, and powerful. There are four kinds of basic entities: individual substances (box a); individual accidents (box b); universal substances (box c); universal accidents (box d).
Now the difference between the bottom row and the top row is found in Plato: Plato recognizes particular things like Socrates and a given chair; he also has kinds of things which he calls Forms, such as Man and Chair. He does not, however, ever make a strong distinction between what Aristotle calls substances and accidents. For Plato, everything in the sensible world is changing, in constant flux, and is hardly stable. What makes objects knowable at all is the fact that they “participate” in Forms. Forms are eternal and absolutely unchangeable. Accordingly, only they are really real. Thus, for Plato, the things on the bottom row (and he doesn’t have an official name for them; he sometimes speaks of them as sensible objects) are dependent items, and they depend on the Forms for their existence and identity. Thus, Plato has a Top-Down theory in which what Aristotle calls universals are prior to and independent of the individuals, while the individuals are dependent on the universals.
Aristotle, however, uses his table to argue the contrary: what is really real consists of what is on the bottom row. Not only that, but it is what is in box a, and consequently in the left-hand column, that is really real. Here is the argument: Socrates is at time t1 pale and at time t2 tan. His conditions, including his complexion, depend on Socrates in a way that he does not depend on his complexion. In general, items in box b depend on items in box a.
To put it in another way, have you ever seen paleness or green or yellow go by? Isn’t color always the color of something concrete? We can say it is Socrates’ complexion, but that is just to say the color belongs to Socrates. Ultimately, all properties are properties of concrete things, substances in Aristotle’s jargon. He goes on to distinguish (in chapter 5 of the Categories) primary substances like Socrates from secondary substances like Man or Human Being. But he makes it clear that, for him, primary substances are primary—they come first. For him, ontology is Bottom-Up. If there were no concrete objects like Socrates and Xanthippe, there would be no Humanity, and no Complexion and no Colors either. Primary Substances, he says, underlie everything else. They are the subjects, the substrata, the foundation for everything else. Box a is, as it were, the cornerstone of his edifice. Without it, everything would collapse.
Notice also a small but very real advantage for Aristotle’s theory: what he maintains is real is just what we humans tend to think is real: people and dogs and cats and horses and tables and chairs and houses. Plato, by contrast, holds that what is real is Justice itself, Beauty itself, Bedhood itself, and the like. Do these things really exist? Yes. Where? In the World of Forms. How can I encounter them? Well, after you die you can behold them … Or you can study philosophy for years and contemplate until eventually you have a mystic vision of them …
The Aristotelian replies, I’ve got what I need right here, thank you very much.
Now the fact that Aristotle does not need to hypothesize insensible realities does not prove that he is right and Plato is wrong. But it does put pressure on Plato to show why he needs to posit mysterious entities when real objects and everyday classes of objects would account for phenomena equally well.
Aristotle goes on to complicate his Ontological Square. He subdivides the right column into nine sub-columns: quantity, quality, relation, place, time, position, possession, action, and affection, laying out all the kinds of properties there are. Unsatisfied with vague generalities, he wants to classify all properties in the proper pigeon-holes. Furthermore, he subdivides the upper row into several levels. For instance (to use some modern distinctions), the lowest kind above Socrates is the species Man or Homo sapiens; above that there would be a higher kind, Primate; above that, Mammal; above that Vertebrate; above that, Animal, above that, Living Thing. Similarly there would be a higher kind above Socrates’ Paleness there is Whiteness, then Color, and so on. Still, however, there is one and only one box of Primary Substance, and that remains the cornerstone of this elaborate ontology.
| cat. | substance | quant. | qual. | relat. | place | time | posit. | poss. | action | affect. |
| univ. | secondary (genus) | |||||||||
| univ. | (genus) | |||||||||
| univ. | (infima species) | |||||||||
| part. | primary |
As we shall see, Plato will soon himself be involved in trying to spell out to a greater degree what kinds of Forms there are and how the relate to each other. Plato seems to be inspired by his student to classify and specify his menagerie of Forms. On the other hand, Aristotle always seems to start from Plato’s conceptions in his own very fertile inquiries—for instance adopting Plato’s two-world ontology as a starting point for his Ontological Square. But he typically goes on to define, specify, and invent technical terminology to clarify what is what and how one item relates to another in a precise way, thus turning Plato’s adumbrations into rigorous theories.
Aristotle will have a new and powerful tool to use: the correlation between words and things. In some way no one, and no philosopher, can help making some connection between words and the things they (allegedly?) represent. But Plato resists making any tight connections between them. He distrusts facile connections and diligently avoids technical terminology. Even for his beloved Forms, he has several terms: eidos, idea, and later genos. Words, he seems to hold, are unreliable for identifying changeless, perfect beings such as the Forms. But Aristotle will do his best to disambiguate language. In the first chapter he focuses on the ambiguity of words—which he recognizes, but does his best to neutralize. Words will become Aristotle’s trusted ally in exploring the world of things. He will deputize them to represent advanced concepts and to analyze facts. He will invent a language of science, capable of great accuracy and precision, of logical consistency and empirical rigor, that will be translated into Latin by later Roman followers, and form the basis of the scientific terminology in modern European languages.
But Aristotle will not be content to construct an alternative metaphysics to that of Plato. He will also invent and/or sharpen arguments meant to refute Plato’s Theory of Forms, to show that it is not only implausible but untenable. Plato will be Aristotle’s inspiration and frustration, as Aristotle will be Plato’s gadfly and nemesis.
[5] Aristotle Categories ch. 4.