“Substance… is that which is not predicated of a subject, but of which all else is predicated” (1029a1)
This paper will attempt to briefly outline Aristotle’s concept of substance. A topic as broad and extensive as this is also formidable to tackle given many perceptions and interpretations associated with it. The concept, especially the interpretive progression has seen many ups and downs. Philosophical literature is full of contradictory interpretations and has to be looked at in its proper context such as its subsequent epochs, the emergence of non-Aristotelian philosophical orientations, etc. As an introduction, the paper will start and end with the ‘conventional’ understanding of the concept that is more or less recognized by various schools. However, given polarization within the philosophical schools, we should bear in mind the fact that there are varying interpretations of the concept substance.
The first thing to draw our attention to when we elucidate this concept is to remember that the concept in Aristotle is intrinsically related to that other concept of metaphysics, namely being. Aristotle says that metaphysics is the study of being qua being. He is explicit about the relation of the two: “what being is, is just the question, what is substance?” Study of being is the study of ousia. But what is ousia? We cannot form an unprejudiced understanding of substance without referring to this crucial term in its original form, as one of the categories of being. Ousia is the Greek word for that which is. It is etymologically derivative of the Greek verb einai – to be. The word substance is the Latin translation of ousia.
Scholars are in disagreement as to whether or not the concept substance conveys all the related meanings associated with the Greek word. The Latin “substantia” denotes something “standing under” something else. Some have argued that both etymologically and historically the concept substance conjures up all the wrong images and ideas. It does not convey what Aristotle wants to convey with ousia. It is often equated, in many non-technical contexts, with staff or material or quantity. The concept ‘Entity’ has been suggested as replacement. The suggestion, however, has not taken off the ground, and it probably would be pointless to attempt to legislate a new concept: “The practice is at this point simply too widespread and too entrenched”.
There are several senses in which a thing may be said to be. In one sense it refers to what a thing is, in another sense to its quantity or quality ‘or has some such predicate asserted of it’. This does not mean that the term being is homonymous. In Metaphysics, however, Aristotle is concerned mainly with the concept Substance, or the ‘what’ which indicates the substance of the thing. Substance is that category of being in virtue of which all other qualifications of being depend. So, for example, describing Socrates as tall says something about Socrates, namely that he is tall. But tallness as a category cannot stand on its own, it must be attached to something, in this case Socrates. Other categories, such as quantity, quality, relation, place, time, position, state, action and affection are not self-subsistent or capable of standing or existing apart from the category of substance which underlies all other categories (except perhaps as pure abstractions). Substance enjoys a sort of logical autonomy, whereas all other kinds of beings are predicated of and dependent on substance. “Clearly then” says Aristotle, “it is in virtue of this category that each of the others is. Therefore that which is primarily and is simply (not in something) must be substance”.
To put it another way, Aristotle is refining the concept of substance by adding two things. First, the Substance must be primary in every sense – ‘in formula, in order of knowledge, in time’. Secondly, it must be simple or basic. A compound cannot be substance. It must remain numerically one and the same while capable of admitting contrary qualities.
Which things are substances? Aristotle recounts various answers that have been given to this question, such as bodies (animals, plants, etc), the limits of bodies or things more basic than bodies (surface, line, points, etc), Plato’s Forms and the objects of mathematics, Speusippus’ the One, etc. In Metaphysics, however, Aristotle wants to know what makes something a substance or to identify the substance of that thing.
He then applies the word Substance to four objects: essence, universal, genus and substratum (or subject). We cannot pursue here the objects to which the word substance applies. We will very briefly consider Aristotle’s consideration of matter and form.
So what makes an x a substance? Is it the matter or the form? He considers matter in some detail and rejects it as impossible; for being separate or independent and particular seem to belong to substance. And matter is neither of them. In fact, in its own right matter is nothing (not a particular, has in itself no determinate quantity…), for it depends upon form for its actual existence.
Aristotle thus argues for the primacy of form, or form as substance. ‘By form I mean the essence of each thing and its primary substance’ (1032b1). Form has all the characteristics which matter lacks, i.e., separability and this something (individuality). Form can stand as it is on its own, it can be separated from the substance in two ways: form can be a plan or a model in the mind of the artist – it is basically something intelligible; or an abstraction from the physical thing.
Form, however, is not merely an ingredient or a component among others. In that case form would not qualify as substance and we would slide into an infinite regress in trying to determine which ingredients is the most basic, i.e., substance. It is rather a principle (arche). A house, for instance, is made of bricks and stones and other materials. Although the house is compound of these components it is not identical with them. The form of the house is not one of the components of the house for the simple reason that a recipe is not identical to the list of its ingredients. It also, for example, includes instructions of how to put the ingredients together. It would be a mistake to consider that the instructions are just another ingredient. Moreover, the existence of the components of the house (the materials the house is composed of) is consistent with the non-existence of the house whose elements they are. Some other principle which is also a cause (aition) must inform the existence of the house. That principle, according to Aristotle, is form. It follows that form is primary and therefore a substance.
 Shields, Christopher. 2007. Aristotle, Routledge, London and New York, p. 173.
 Tollefsen, Torstein Theodor, Hva er metafysikk? Grunnleggende trek ved aristotelisk metafysikk.