Substance in the Categories
Aristotle became a student in Plato’s Academy when he was about seventeen years old. He seems to have developed his theory of categories fairly early in his life. It is a very un-Platonic theory, which shows some important advances over the theory of his master. According to Plato, the ultimate realities are “Forms,” which are changeless and embody perfect exemplars of characteristics, such as Justice and Equality. When we are just, for instance, we “participate” in Justice Itself, or the Form of Justice. But nothing in our world is completely such-and-such, for instance just, because things in our world are changeable and imperfect. So there is a perfect world of Forms, let’s call it Formland, and an ever-changing world of experience, call it Changeland.
Aristotle sees things differently. In the short (but hard-to-read) treatise The Categories, he distinguishes between something like things that participate in Forms and Forms, and also between things and attributes of things.
Here is a table illustrating his theory:
| universal | a) Man, Dog “secondary substance” | b) Knowledge, Whiteness |
| individual, particular | c) Socrates, Fido “primary substance” | d) Soc’s knowledge of A, Soc’s pale complexion |
| substance (thing) | accident (attribute, property) |
The top row (boxes (a) and (b)) correspond to Formland, the bottom row ((c) and (d)) to Changeland. Aristotle makes it clear, however, that for him the most important box, the one that represents Real things, is (c): if there weren’t concrete objects like Socrates and Fido, there would not be anything like a Form of Man or Dog. Similarly, there would not be attributes like paleness and shagginess. He calls the items on the bottom row “individuals” or “particulars”; the items on the top row “universals.” And he maintains that things on the top row depend on things on the bottom row rather than vice versa. For instance, if there weren’t things like Socrates and Sappho, there would not be human beings; if there were not things like Fido and Fifi, there would not be dogs. (Plato holds that Forms always exist whether they are exemplified in Changeland or not.)
The column on the left (boxes (a) and (c)) contains “substances” or concrete things; the column on the right (boxes (b) and (d)) contains “accidents” or attributes. Attributes always belong to things, just as Socrates’ complexion is a feature of Socrates, and Fido’s shagginess is a feature of Fido. You never see a color or a shape just floating by: it is always a color or shape of something concrete, such as a man or a dog.
Aristotle also distinguishes between essential connections on the one hand, and accidental or incidental connections on the other. Socrates is essentially a man, Fido essentially a dog. But Socrates is only incidentally pale or literate, Fido incidentally shaggy. So there are traits that define things (humanity defines Socrates, doghood defines Fido) and other traits that are incidental (whether Socrates is pale or tan). Socrates can change complexion without ceasing to be, but he can’t change his essence (if a witch turns him into a toad, he is not longer Socrates, according to Aristotle).
Aristotle’s theory has a powerful appeal: it tells us that the things we tend to think are real and important ARE real and important. For instance, you and I, Socrates and Sappho. On Plato’s theory, we at best second-rate existences. It is even worse for other early philosophers, such as Democritus the atomist. According to him, you and I are just a (changing) heap of atoms that survive only temporarily and then decompose into their real components, namely the eternally existing atoms.
Aristotle call us and concrete things like us “substances.” Indeed each one of us is a “primary substance” (prōtē ousia) or primary reality; the kinds we belong to are “secondary substances.” But the items in boxes (a), (b), and (d) are all dependent for their existence on items in (c): if we primary substances did not exist, nothing else would exist. Nothing would have properties or exemplify kinds.
This theory supports common sense experience and puts us at the center of the world of reality. But it has a problem. Theoretically, primary substances are simple. Nothing is more fundamental than, for instance, Socrates. If you saw Socrates in half, you don’t get two more important things, but just two yucky dead things. That seems fair enough. But since Socrates is an “individual” (atomos, meaning “indivisible” thing, the word ‘atom’ comes from), he either exists or he doesn’t. He can’t really come to be. Yet Aristotle is a pretty good biologist, among other things, and he knows perfectly well that Socrates takes nine months plus twenty years, give or take, to become the full-grown philosopher. So how can we account for the facts of life?
Matter and Form in the Physics
Aristotle confronts the problem in Physics book I. Lurking in the background is the early philosopher Parmenides of Elea, who had insisted that there is no change. For what-is is, and what-is-not is not, is nothing. For something to come-to-be it must come-to-be from what-is-not, or nothing, and that is impossible. So there is no change. Subsequent philosophers developed working hypotheses, but no one had ever given a definitive answer to the so-called “Eleatic Challenge”: how can what-is come from what-is-not?
Aristotle realized that on his view, what is real is what underlies everything else as a subject. For instance, Socrates is the subject of manhood and paleness. To be real, then, is in some sense to underlie and to continue through other changes (like that from pale to tan). Well, what underlies the coming-to-be of Socrates? At some point there is a biological stuff that at first is not a man (human being), but later is a man. It is like a pile of boards that at first is not a house, but then (by being hammered together) becomes a house. There is some stuff that first is not-formed and then formed. The boards are present throughout the development, but they gain a new structure and function. First they are not-F and then they are F. But they are always there as the stuff underlying the change. Call it the matter and call the F form. This is a model for what happens in the birth of Socrates: some biological matter acquires the right form.
Aristotle invents the generic word for matter (hylē). (Greek philosophers had been talking about kinds of matter for a long time without having a general word for it.) He also uses his model to answer Parmenides and his Eleatic Challenge: in this version, matter goes from being not-formed to being formed. In the change, there is always something present, even if it is not the final product: there is no “nothing” in the story. So expressions involving ‘not’ do not entail nothingness: for instance not-F just means ‘lacking F,’ and in his story, there something lacking F. Parmenides is guilty of confusing different senses of not-being.
(There is, however, one more step: the difference between not-F and F is still an “either-or” either it is F or it is not F, yes or no, 1 or 0. We need a sliding scale of reality to allow for gradual development, for instance of Socrates’ fetus to the mature Socrates. Aristotle invents that, too: he distinguishes between what is potential and what is actual, a scheme he sometimes equates with matter and form. But they are not the same scheme, because the former is digital, the latter analog. What is potential becomes more and more real over time. For instance, an acorn may take a hundred years to be become a full-grown oak. But we posit a sliding scale of actuality from less to more actual over the period of growth.)
Aristotle’s so-called logical works, written early in his career and comprising the writings from the Categories to the Topics, show no evidence of a theory of form and matter. From the Physics on, analyses of form and matter are everywhere in his writings. It appears that Aristotle modified his theory by introducing form and matter (using the Greek roots, he invented hylomorphism), which then became his new and improved theory of reality, one that could account for how primary substances come-to-be and perish, as indeed they do in the natural world.
Substance, Matter, and Form in Metaphysics VII
In the Metaphysics, presumably written late in his career, Aristotle revisits his theory of substance. In book VII he briefly considers what candidates his predecessors have proposed as being ultimately real, including the Presocratics, the Pythagoreans (a special group of Presocratics), Plato and the Platonists. Then in chapter 3 he focuses on different concepts of reality: 1) the essence; 2) the universal; 3) the genus; and 4) the substratum. The first three will largely overlap, but for now he concentrates on the last, the substratum. He breaks down that concept into three versions, 4a) matter, 4b) form, and 4c) the compound of matter and form. Here he asks which one of these is the ultimate reality. This is a somewhat odd move, because up till now he has been arguing with his predecessors. But at this point he starts to argue with and second-guess his own powerful and successful hylomorphic theory. For he is the only early philosopher to embrace a theory of matter and form.
There is one oddity here: (4b) form does not seem to qualify as a substratum or underlying subject. The other versions are clearly substrata: (4c) the compound, for example Socrates, is the subject of all his properties; (4a) matter is the subject of the form, which components together constitute Socrates. But form is not a substratum of anything. But let that go for now.
Aristotle examines (4a) matter. In a thought experiment he imagines stripping away all the determinate properties of a thing. What will be left? Only the matter. But the matter itself is now totally indeterminate because of having lost all its properties. So it cannot qualify as a concrete thing that is the permanent subject. We are left with something some contemporary philosophers call a “bare particular,” something lacking any real character and serving only as a placeholder.
What about (4c) the compound of form and matter? That “may be dismissed; for it is posterior and its nature is obvious” (1029a31-32). In other words, it is made up of elements that are evidently prior to it, one of which must be the ultimate real thing. But we have already eliminated matter, so we are left with form as the last concept standing.
In chapter 4 we change focus to (1) essence. This is a bit of a jump, but as we shall see, all the other concepts of substance have something in common with (4b) form, so Aristotle seems to hope that focusing on essence will illuminate form. “The essence of each thing is what it is said to be [in virtue of itself]” (1029b5-16, Ross trans. throughout). So what is essence? Aristotle talks about this here, but not always clearly. The notion of essence is present already in the Categories. In Aristotle’s Ontological Square, the essence is given by what stand above the object in question. What is Socrates? A man. What is a man? A rational animal. According to Aristotle, the first answer tells what Socrates is, but it is not a full-blown essence, because it does not really define a thing. Indeed, you can’t really define Socrates. You can recite is biography, but that is not a real definition, which has to be general, not a list of particular events. As he gradually makes clear in chapters 4-6, only something that is itself general can be defined. Like man (human being). Man is a rational animal.
Here we get a scheme of explanation: S = D (G); the species is a differentia of a genus. The species is a lower-level universal, the differentia identifies a special characteristic, and the genus gives the higher-level universal the lower-level universal falls under. So man is a kind of animal. What kind? One that is rational. We can use the distinction ‘rational’ to divide the genus Animal so as to get the species Man. This scheme comes from the late Plato, who came to believe that by judiciously arranging the Forms we could come to a classification of all things. Aristotle explains: “There is an essence only of those things whose formula is a definition” (1030a6-7). But, he goes on to say, not just any string of words can count as a definition, for in that case the long poem in twenty-four books would be the definition of the title Iliad! (A rare Aristotelian joke.) Rather, we must have “a formula of something primary; and primary things are those which do not imply the predication of one element in them of another element. Nothing, then, which is not a SPECIES of a GENUS will have an ESSENCE” (1030a10-12, emphasis added). So: if the formula of an essence excludes the predication of one thing in it of another, the compound of form and matter does not qualify. The species will be the subject of definition. And it will be PRIMARY.
Aristotle goes on to say at the end of chapter 5, “Clearly, then, definition is the formula of the essence, and essence belongs to substances either alone or chiefly and primarily in the unqualified sense.” And in the last paragraph of chapter 6 he says, “Clearly, then, each PRIMARY and SELF-SUBSISTENT THING is one and the same as its essence” (emphasis added).
On the one hand, the train of reasoning seems perfectly sensible. The thing that makes Socrates what he is, Man: the form of man in this-here matter. And man stands for the “infima species,” the lowest-level universal Socrates stands under. It is definable as Rational Animal.
On the other hand, something is really wrong here. In the Categories, the primary substance was Socrates, and Man was the secondary substance. Now, however, Man is the primary substance, and Socrates is ruled out a priori as being a conglomerate of two prior things. How can Aristotle claim to be defending his own theory, when he seems to be promoting universals as the ultimate reality? Isn’t he selling out to Platonism?
In chapters 7-9 he talks about form and matter, but without particularly advancing his own inquiry. In chapter 10-12 he explores essence further. If S = D (G), then what is the ultimate reality? Is it the differentia D, which specifies what the species is? Or is it G, which is the basic reality which gets divided? In the Categories, however, Aristotle claimed that the most real is what is lowest in the Square. And the lower kinds are more real in principle than the higher kinds. Now, it seems, he is abandoning that assertion and saying that the higher you go, the more real is the kind. Shades of Platonism.
[Note: in the Ontological Square above there are only four boxes. But as he goes on in the Categories, Aristotle makes it clear that the upper row, that of universals, can be subdivided into higher and lower universals, such as Man falls under Animal, Animal under Living Thing. Also, the right column of accidents he subdivides into nine sub-columns of Quality, Quantity, Relation, etc., giving the ten canonical “categories” of Aristotle. So the table can be expanded further.]
Finally, in chapter 13, Aristotle seems to come to his senses. When he starts to examine (2) substance as universal from his chapter 3 list, which includes the species, genus, and form, he says, “it seems impossible that any universal term should be the name of a substance. For firstly the substance of each thing is that which is peculiar [unique] to it … but the universal is common … Further, substance means that which is not predicable of a subject, but the universal is predicable of some subject always” (1038b8-11, 15-16). He remembers the characterization of substances from the Categories. “It is plain,” he concludes, “that no universal attribute is a substance” (b34-35).
Aristotle finally realizes he has been heading down the primrose path to Platonism. He stops just in time. He muddles through four more chapters, and then picks up the inquiry in book VIII of the Metaphysics, where he recapitulates, and then muddles some more. He has, it seems, dodged a bullet. But what is the right answer? We seem to get only wrong answers in this book. What does the real hylomorphic metaphysics of Aristotle look like?