Aristotle’s Metaphysics: Substance, Form, and Nature
Substance
Substance refers to an independent entity, that which predicates the attributes. From the Latin substantia, a translation of the Greek ousia. Etymologically, “that which stands below.” It has a complex meaning, designating:
- That which underlies the properties: for example, Socrates, to whom we predicate the traits of being Athenian, being a student of Plato, etc.
- That which remains through accidental change: Socrates remains the same individual, although his appearance may change over time.
- The independent being, that which has its being not in another but in itself: we distinguish the level of attributes (being white, small, and intelligent, for example, which do not have independent existence, but always exist in something else, which we say are their properties) and the level of substance (which has its own and independent existence, such as Socrates, a stone, or a tiger).
Aristotle distinguishes two types of substances:
- Primary substances are individual subjects, composed of matter and form. Example: concrete individuals, such as Socrates.
- Secondary substances refer to genera and species. Example: human, animal, vegetable.
When we ask “What is this?”, we want to know the nature of something. We want to clarify what type of substance it is. We can answer the question “What is this book?” by indicating the primary substance, but we can also answer by indicating the secondary substance. The notion of ‘secondary substance’ is used to designate the natures of things, understood as species and genera. In the case of Socrates, Socrates himself is the primary substance, and human is the secondary substance.
Matter
The nature of matter is that which determines a thing. From the Greek term hyle. This term originally meant wood; construction material, the element with which something is built.
Matter is that out of which something is made. Along with form, it is one of the elements establishing substances. From an individual and dynamic point of view, it is that which is susceptible to any determination or form, both potential and actual. We can also speak of matter as a relative character: if we look at a statue of the god Zeus, its matter is bronze; but if we look at bronze itself, bronze is the primary matter.
In the case of living beings, matter is considered as the body and soul.
- Primary matter: matter without any form. It is not perceptible by the senses and is the ultimate substrate of substantial change.
- Secondary matter: determined, shaped matter. Example: the matter of a statue is marble.
Form
Form is the set of characteristics of an object. This term corresponds to the Greek word morphe. Our language captures quite well the meaning of this word in Greek philosophy and in Aristotle: on one level, it is identified with the figure of a physical object, while on another, it designates the structure of something, the elements or components that make something what it is, as when we speak of the structure or form that a poet gives to their verses or a writer presents to us in a book. More generally, and in a typically Aristotelian sense, we can speak of form as the characteristics of an object and distinguish between accidental and substantial form: the substantial form of a thing is the same as its essence, and the accidental forms are the determinations or properties of which the subject can be deprived without suffering a substantial alteration.
Aristotle’s position regarding whether form is independent or dependent differs from that of Plato. For the latter, the form or idea of things exists separately in the world of ideas. For Aristotle, forms are enrolled in individuals, corresponding to the metaphysical composition of matter and form. In the case of living beings, the soul is substantially the form.
Aristotle’s theory of hylomorphism states that sensible beings (both natural and artificial) are composed of matter and form. This theory explains the substance and the distinction between primary and secondary substances.
Nature
Nature consists of the intrinsic principle of movement and rest of natural beings. From the Latin word natura, a translation of the Greek physis. This notion was very important to Greek philosophers, but Aristotle was the one who studied it most thoroughly. All his philosophy revolves around this concept, in the same way that Plato’s revolves around the concept of ideas. For Aristotle, nature shows us moving beings composed of matter and form.
For a Greek, physis is that from which beings arise. Aristotle’s concept of physis has the following meanings:
- Origin: physis is the origin from which beings spring.
- Essence: it is that which remains through change, that which makes a thing what it is.
- Movement: for Aristotle, nothing is as evident as the fact that things move. The set of natural beings would be those that have in themselves the principle of movement.
Nature has a divine character in Aristotle: changes occur harmoniously, with regularity and rhythm. Aristotle says that nature does not have a god, but a divine character. All nature tends toward an end (teleology).
Ontology is the doctrine that considers reference to the ends or motives for which something happens indispensable for understanding nature. It comes from logos (reason) and telos (end). Teleology explains the existence of movements in natural beings.
Aristotle inherited the teleological conception from Plato, although for Plato the purpose of human beings is to know the good, and for Aristotle it is to achieve happiness.
Act and Potency
This is one of Aristotle’s most important contributions, aimed at giving a satisfactory explanation to the becoming of substance. The distinction between potency and act arose as a successful attempt to deal with the physical problem of movement.
The author says that if we observe natural beings, we realize that they not only change but also that they cannot change in just any way.
Beings can change, but within limits, within possibilities. These possibilities of change are what Aristotle calls potency (it is a non-being, not absolute, but relative non-being) and what the being already is, he calls act. We have, therefore, another two modes of being: being in act (cold water) and being in potency (cold water has the potential to be heated). Thus, beings can change if they have the possibility to do so.
Movement, change, is defined as the passage from potency to act (from the potency of being heated to being in the act of being heated).
Aristotle analyzes the changes that occur in nature and concludes that there are two possibilities: substantial changes (when a being is generated or disappears, a replacement of one substance by another occurs) and accidental changes (in which the substance modifies some of its qualities or attributes but remains the same):
- Substantial changes lead to the generation or corruption of the being (birth and death).
- Accidental changes can be of three types: quantitative (increase or decrease), qualitative (alteration), or locative (displacement).