Thinking about Substance

The Development of Aristotle's Thought

Outline of Categories 1-5:

Chapter 1. Names
Chapter 2. The division of reality
Chapter 3. Predicates
Chapter 4. The ten categories
Chapter 5. Substance
In the Metaphysics, Aristotle tries to correct what he sees as mistakes in the ontology and theory of substance and existence he presented in the Categories.

The Ontology in the Categories


In general, it is unknown when Aristotle wrote particular works. The Categories, though, is an exception. It is thought to be one of Aristotle's earliest works.
The Categories is an early work written not long after Aristotle left the Academy.


"Of the beings: some are said of a subject but are not in any subject. Man is said of a subject, this or that man, but is not in any subject. Some are in a subject but are not said of any subject. ... Some are both said of a subject and in a subject. For example, knowledge is in a subject, the soul, and is also said of a subject, knowledge-of-grammar. Some are neither in a subject nor said of a subject, for example, the this or that man or horse—for nothing of this sort is either in a subject or said of a subject. Things that are atomic and one in number (ἄτομα καὶ ἓν ἀριθμῷ) are, without exception, not said of any subject, but there is nothing to prevent some of them from being in a subject. Knowledge-of-grammar, for example, is one of the things in a subject" (Categories 2.1a).

"A substance (οὐσία)--that which is called a substance most strictly, primarily, and most of all--is that which is neither said of a subject nor in a subject, e.g. this or that man (ὁ τὶς ἄνθρωπος) or this or that horse. The species in which the things primarily (πρώτως) called substances are, are called secondary (δεύτεραι) substances, as also are the genera of these species. This or that man belongs in a species, man, and animal is a genus of the species; so these--both man and animal--are called secondary substances" (Categories 5.2a).
The discussion is about terms. Terms are parts of language. To identify the parts of reality terms signify, "All the other things are either said of the primary substances (πρώτων οὐσιῶν) as subjects or in them as subjects. ... So if the primary substances did not exist it would be impossible for any of the other things to exist" (Categories 5.2a).

Aristotle uses ὁ τὶς ἄνθρωπος ("this man") to refer to a particular man, this or that man, as opposed to ἄνθρωπος ("man"), the kind to which human beings belong.

"It is reasonable that, after the primary substances (πρώτας οὐσίας), their species and genera should be the only other things called secondary substances (δεύτεραι οὐσίαι). For only they, of things predicated, reveal the primary substance. For if one is to say of this man what he is, it will be in place to give the species or the genus (though more informative to give man than animal); but to give any of the other things would be out of place--for example, to say white or runs or anything like that" (Categories 5.2b).
Aristotle divides reality (τὰ ὄντα, "the beings") according to what is "said of a subject" and what is "in a subject." What is and is not "said of a subject" is what is general and what is particular. What is and is not "in a subject" is a little more confusing, but it seems to be what is a property and what is an object. The result, then, is a division along two dimensions:

particular versus general
object versus property

Plato, with his Theory of Forms, had emphasized the ontological division between particular and general. Aristotle accepts this division and thinks there an equally important division that Plato overlooked. Aristotle thinks, it seems, that there is a division between objects and properties. Thus, according to Aristotle, in reality there are four kinds of "beings": (i) particular objects, (ii) particular properties, (iii) general objects, and (iv) general properties.

Aristotle makes particular objects the "primary substances" (πρῶται οὐσίαι). They are the foundation for existence in that everything else depends on them for its existence.

There are lots of questions to ask about Aristotle's ontology, but the first thing to notice is that it is much more striking than it may initially appear. Consider the sentences,

• Socrates is a man, Socrates is pale

Aristotle understands the term 'Socrates' to signify a particular object, Socrates. He understands 'man' to signify an object too, and this can be surprising. One might think that although individual human beings exist, man does not exist. Further, if man does exist, one might think it is a property. According to Aristotle, however, 'man' signifies a general object, man.

Aristotle's understanding of the second sentence can be surprising too. One might think 'pale' signifies a general property, but this is not how Aristotle understands the sentence. He takes the term to signify a particular property and takes the sentence to be true if the particular object the term 'Socrates' signifies contains the particular property the term 'pale' signifies.

The Oneness of Individuals


"Every substance seems to signify a this (τόδε τι). As regards the primary substances, it is indisputably true that each of them signifies a certain this; for the thing revealed is individual (ἄτομον) and one in number. But as regards the secondary substances, though it appears from the form of the name--when one speaks of man or animal--that a secondary substance likewise signifies a certain this, this is not really true; rather, it signifies a certain qualification--for the subject is not, as the primary substance is, one, but man and animal are said of many things" (Categories 5.3b).
Aristotle's explanation of the individuality of particular objects can also be surprising. Socrates is one thing, not a some things heaped together. The philosophical problem is to explain this oneness. For Aristotle, the particular objects he identifies as primary substances have the oneness and unity characteristic of individuals because they are the "atomic" parts of general objects.

What Aristotle has in mind is not easy to see, but the idea is that the general object animal, for example, is divisible into more specific general objects, such as man. Man is not further divisible into general objects, but it is divisible into the many particular men. These men are indivisible (because the parts of human beings are not human beings) and hence they are the "atomic" parts of man. This indivisibility is the oneness that makes a particular man an individual.

Problems in the Ontology

Aristotle does not explain why he returns to the question of substance in the Metaphysics, but it is natural to think he realized that "this or that man" cannot be a primary substance and so cannot be what underlies the properties and makes them properties of one object.

The problem is that "this or that man" is a particular object with a set of particular properties. The "this or that man" is a certain human being with a certain height, weight, and so on. So it is unclear what "this or that man" is so that it is a subject for and distinct from its properties.

Change also poses a problem for the ontology.

We ordinarily think that it is possible for Socrates to become pale, for example. He would not be pale at one moment and would be pale at a later moment, but it is not clear this change can be accommodated in the ontology in the Categories because it is unclear what would persist.

"[W]hat is most characteristic of substance appears to be this: that, although it remains, notwithstanding, numerically one and the same, it is capable of being the recipient of contrary qualifications. Of things that are other than substance we could hardly adduce an example possessed of this characteristic. For instance, a particular colour, numerically one and the same, can in no wise be both black and white, and an action, if one and the same, can in no wise be both good and bad. So of everything other than substance. But substance, remaining the same, yet admits of such contrary qualities. One and the same individual at one time is white, warm or good, at another time black, cold or bad. This is not so with anything else" (Categories 5.4a).

We also ordinarily think that Socrates is not immortal, that he came into and then later went out of existence. These kinds of change also pose problems for the ontology.
This problem, it seems, perhaps among others, convinces Aristotle to think again about what things are substances. His thought in the Metaphysics remains a matter of debate among historians, but it seems clear that he no longer thinks the primary substances are "this or that man" and "this or that horse," where these objects are understood as the particular objects familiar from experience: concrete objects of a certain size, weight, color, and so on.

Further, in the Metaphysics, although again this is a matter of debate, Aristotle no longer thinks that general objects such as man and horse exist. So he can no longer accept the explanation he works out in the Catagories for the individuality of Socrates and the other particular objects. If there are no general objects, particular objects cannot be the atomic parts of general objects. So, in the Metaphysics, for whatever Aristotle identifies to replace "this or that man" as a primary substances, he also needs a new explanation of how it is an individual object.

Primary Substances are Forms

In the Metaphysics, as we saw in the prior lecture, Aristotle thinks that a substance

• is a "subject" for the predication of properties
• is "separate" from its properties
• has a oneness and unity and so is a "this."

This suggests to him that forms are the primary substances, not the concrete objects (the "this or that man" and "this or that horse") he identifies in the Categories. Somehow forms are subjects for properties, have an existence separate from properties, and is each a "this."

Further, in the Metaphysics, there are substances with qualification and substances without qualification. The primary substances are the substances without qualification. The forms of "this or that man" are substances, but they are substances with qualification. They are forms in matter. These substances take the place of the "secondary substances" in the Categories. In the Metaphysics, Aristotle seems to think that general objects are not part of what there is.

"For physics is about things that are separable [in a way because they are separable in account] but are not immutable [because they are in matter], .. but the first [philosophy] is about things that are both separable and immutable (χωριστὰ καὶ ἀκίνητα)" (Metaphysics VI.1026a).

Substances With and Without Qualification

We can begin to understand the existence of a substance with qualification as a form in matter if we take the way Aristotle conceives of the human soul as an example.

A substance with qualification is a substance, so first of all we need to see how the human soul as a form in matter is a substance. It is a subject for the predication of properties. Socrates, for example, has a certain height and weight. These properties characterize the organization of the matter in the form of a human being. Further, the form in matter can exist without these particular properties. Over his lifeime, Socrates was different heights and weights. What persists in these changes is the organization of matter in the form of a human being.

The form in matter is a substance with qualification because it meets the condition for substance with qualification. As the organization of matter into the form of a human being, the soul cannot exist separately from matter. The soul, however, is separate from matter in a way because the account does mention flesh, bone, or any other material. In this way, the soul is "separable" but with qualification. Its existence is separate from matter in account.

The soul is also "immutable" with qualification. The human soul is the starting-point for certain changes in a human being, and although it does not get angry or become more or less wise, it is not the same at every point in time. The human soul, first of all, does not exist eternally.

Further, although this is difficult to understand, the human soul is different at different times in the life of a human being. So, for example, before the acquisition of reason, when the human being is a child, the organization of the matter that constitutes the child is a certain way. It is a way that explains the behavior of children. Subsequently, after the acquisition of reason, when the human being has matured and has become an adult, the matter that constitutes the adult is organized in a different way. It is a way that explains the behavior of adults.

Actuality and Potentiality

It remains to know how the explanation of existence as a form includes (because theology as first philosophy is universal) an explanation of existence as a form in matter.

The answer is difficult to see clearly, but it seems to be that existence as a form is existence as an actuality without potentiality. To explain this existence, it is necessary to explain existence as an actuality with potentiality. This existence, it seems, is existence as a form in matter.

To see how Aristotle understands form and matter in terms actuality and potentiality, it helps, again, to consider his discussion of the soul. In On the Soul, once he turns to the question of what the soul is, Aristotle immediately starts talking about substances. The implication is that souls are substances, but before he makes this argument, he explicates substances in terms of matter and form and explicates matter and form in terms of potentiality and actuality.

"[Let us] try to determine what the soul is, and what definition of it will be most comprehensive. We describe one of the kind of beings as substance; and in this there is matter, which in itself is not a this (τόδε τι); shape or form, that according to which something is a this, and the compound of the two. Matter is potentiality, and form is actuality (ἔστι δ᾿ ἡ μὲν ὕλη δύναμις, τὸ δ᾿ εἶδος ἐντελέχεια)..." (On the Soul II.1.412a).

Given this very brief discussion of the ontology in terms of which he will say what the soul is, Aristotle goes onto argue that the soul is the "first actuality" of a certain kind of body.

"Of the natural bodies, some have life and some do not. Life we say is self-nutrition and growth and decay. Thus every natural body having life is a substance as a composite. But since it is a body of a definite kind, viz., having life, the body cannot be soul, for the body is not something predicated of a subject, but rather is itself to be regarded as a subject, i.e., as matter. So the soul must be substance as the form of a natural body, which potentially has life. And substance is actuality. The soul, then, is the actuality of a body. But actuality is of two kinds, corresponding to knowledge and contemplation. The soul is an actuality like knowledge. Sleeping and waking presuppose the existence of soul, and waking corresponds to contemplation, sleeping to knowledge since it comes first. That is why the soul is the first actuality (ἐντελέχεια ἡ πρώτη) of a natural body having life potentially in it" (On the Soul II.1.412a).

This provides a glimpse into how the sensible substances physics studies (forms in matter) have an existence that is a qualification of the existence of the divine substances theology studies (forms). Since divine substances are forms, it falls to theology to explain what existence as a form is. The explanation will be that forms exist as actualities that do not involve any potentialities. Their existence is existence as a "pure" actuality. Further, because the explanation of existence as a "pure" actuality includes an explanation of existence as an "impure" actuality (an actuality involving potentialities), theology is first philosophy and so "universal in that it is primary" (Metaphysics VI.1.1026a). Existence as an actuality involving potentialities is the existence as a form in matter that characterizes the substances physics studies.




Perseus Digital Library:
Aristotle, Metaphysics

Henry George Liddell, Robert Scott, A Greek-English Lexicon:
ἀκίνητος, akinētos, adjective, "immovable"
ἄτομος, (ἀ + τέμνω), atomos, adjective, "uncut"
μεταβολή, metabolē, noun, "change"
μεταβάλλω, metaballō, verb, "turn about, change, alter"
χωριστός, chōristos, adjective, "separable"

Arizona State University Library: Loeb Classical Library.
Aristotle, Categories, Physics I-IV




"In the Metaphysics, Aristotle denies that there is anything general--at least, he denies that there are kinds [animal, man, and so on] into which objects fall. Thus, he also abandons the notion of an individual which he had relied on in the Categories, since it presupposes that there are general things, that there are universals" (Michael Frede, "Individuals in Aristotle," 50. Essays in Ancient Philosophy, 49-71). "In the Metaphysics, Aristotle denies that there are genera or species [animal, man] that is, he denies that universals really exist (cf. [Metaphysics] Z 13). Yet, if there are no genera and species, individuals no longer can be taken to be the ultimate, indivisible [or "atomic"] parts of genera [as he claimed in the Categories]" (Michael Frede, "Individuals in Aristotle," 63. Essays in Ancient Philosophy, 49-71).

"[In the Metaphysics, Aristotle] sees that it cannot be the ordinary objects of experience [this or that man, this or that horse] that underlie the properties, if there are to be properties in addition to the objects; for the ordinary objects of experience are the objects together with their properties—an ordinary object has a certain size, weight, temperature, color, and other attributes of this kind. So, if we ask what is it that underlies all these properties and makes them the properties of a single object, we cannot answer: just the object. For the object, as ordinarily understood, already is the object together with all its qualities; what we, however, are looking for is that which underlies these qualities. Thus we can see why Aristotle now considers answers like 'the form' or 'the matter' when considering the question, what actually is the underlying substance" (Michael Frede, "Individuals in Aristotle," 64. Essays in Ancient Philosophy, 49-71).

"Although [in the Metaphysics] he retains the primary substances of the Categories, namely objects, these must now yield their status as primary substances to their substantial forms which now come to be called primary substances. The substantiality of concrete particulars [this or that man] is thus now only secondary. The idea of the Categories that substances are that which underlies everything else is retained, as we see from Metaphysics] Z 1 and Z 3. However, the answer to the question what is it that underlies everything else has changed: now it is the substantial form" (Michael Frede, "The Title, Unity, and Authenticity of the Aristotelian Categories," 26. Essays in Ancient Philosophy, 11-28).

"[In the Metaphysics,] Aristotle thinks that substances are not as such composite. There are substances that are pure forms, as e.g., the unmoved mover. And it is clear from [Metaphysics] Z 3,1029 b 3ff. and Z 11, 1037 a 10ff. (cf. also Z 17, 1041 a 7ff.) that Aristotle thinks that the discussion of composite substances in [Metaphysics] Z [and Metaphysics] H is only preliminary to the discussion of separate substances. We start by considering composite substances because they are better known to us, we are familiar with them, and they are generally agreed to be substances. But what is better known by nature are the pure forms. Aristotle's remarks suggest that we shall have a full understanding of what substances are only if we understand the way in which pure forms are substances. This, in turn, suggests that he thinks there is a primary use of 'substance' in which 'substance' applies to forms. Particularly clear cases of substance in this first use of 'substance' are pure forms or separate substances. It is for this reason that composite substances are substances only secondarily" (Michael Frede, "Substance in Aristotle's Metaphysics," 79. Essays in Ancient Philosophy, 72-80).

"[S]ubstantial forms rather than concrete objects are the basic entities. Everything else that is depends on these substantial forms for its being and for its explanation. Hence substantial forms, being basic in this way, have a better claim to be called 'ousiai' [οὐσίαι] or 'substances"' than anything else does. Some of them are such that they are realized in objects with properties. But this is not true of substantial forms as such. For there are immaterial forms. Properties, on the other hand, cannot exist without a form that constitutes an object. Moreover, though certain kinds of forms do need properties for their realization, they do not need the particular properties they have. The form of a human being needs a body of a weight within certain limits, but it does not need that particular weight. No form needs that particular weight to be realized. But this particular weight depends for its existence on some form as its subject. In fact, it looks as if Aristotle in the Metaphysics thought that the properties, or accidental forms, of objects depended for their existence on the very objects they are the accidental forms of, as if Socrates' color depended on Socrates for its existence. However this may be, on the new theory [in the Metaphysics that supercedes the theory in the Categories] it is forms that exist in their own right, whereas properties merely constitute the way forms of a certain kind are realized at some point of time in their existence" (Michael Frede, "Substance in Aristotle's Metaphysics," 80. Essays in Ancient Philosophy, 72-80).

"[I]t would seem that the forms of natural substances ... are separate only qualifiedly, namely, in account; and they are unchanging, but only qualifiedly. For though they do not come into being or pass away, they, unlike separate forms, do not exist eternally, but go in and out of existence instantaneously. And though they do not suffer change, they really are different at different times, as one can see in the case of human souls" (Michael Frede, "The Unity of General and Special Metaphysics: Aristotle's Conception of Metaphysics," 91. Essays in Ancient Philosophy, 81-95).

"[T]he forms at least of ensouled things [such as human beings] are not subject to change, at any rate, not in the sense in which Aristotle's natural philosophy approaches changeable objects, though they are principles of change and can have a very rich history, simply because the characteristic capacities of a living thing—which are what constitutes the soul, i.e., the form—can at various times be exercised or not exercised. If one sees something, it is not strictly speaking the soul which is undergoing some change but the living organism; nevertheless,the soul is a different soul, if one sees or has seen something" (Michael Frede, "Individuals in Aristotle," 69. Essays in Ancient Philosophy, 49-71).

"A human soul ... is in different states at different times, depending on whether the potentialities it is constituted by are actualized or exercised or not" (Michael Frede, "Introduction," 44. Aristotle's Metaphysics Lambda, 1-52).




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