24.01S16 Matter and Form, Body and Soul, in De Anima

24.01: Classics of Western Philosophy

Haslanger

Matter and Form, Body and Soul, in De Anima

• Follow-up on Final argument in Plato’s Phaedo.

• Introduction to Aristotle (see additional biographical handout).

1. Hylomorphism

Unlike Plato, Aristotle was fascinated by the natural world. Instead of Plato’s division between two vastly

different realms, Aristotle distinguishes two aspects of ordinary things – form and matter. Form only exists when it

enforms matter; moreover, matter is just potential to be enformed. Aristotle identifies matter with potentiality,

form with actuality. Think of a carved statue: the wood is the matter, the potential statue; the shape is the form,

which makes it an actual statue; the matter/form complex is the individual thing, the statue.

In the case of artifacts like statues, we impose form on the matter. But the form/matter in statues is just an

analogy to help us understand the basic idea. Aristotle was mainly interested in explaining the characteristic

changes in and growth and development of natural things. Why does water boil when heated and freeze when

cold? Why do some trees produce apples and others oranges? Why do human embryos develop into adult

humans and dog embryos develop into adult dogs? This can’t be explained simply by their matter (which is

basically the same stuff), but by the form that makes something water, or an apple tree, or a human, i.e., in

virtue of which the things are what they are. In ‘On the Soul’ we find Aristotle applying his wider metaphysical

views to the topic of living things.

. What is soul?

A. Basics

Note that ‘soul’ translates psuchē (cf. ‘psyche’). In its most basic sense, the psuchē is what gives life to living

things. This is the sense Aristotle is working with. Aristotle takes it for granted that to have a soul is to be alive:

and ‘by life we mean self-nutrition and growth and decay’. So even plants have a kind of psychē. But humans

have a more complex psuchē. Broadly speaking, there are three classes of capacities of living things. Aristotle

arranges these hierarchically: higher-order living things possess all the capacities of lower-level living things:

i. Nutrition (and generation): plants and animals

ii. Perception: all animals

iii. Thinking (or understanding): humans and “any thinking being that is different from, or superior to, a

human being,” e.g., God. (414b17).

In order to understand Aristotle’s view it helps to consider some rival conceptions of soul: dualism and

materialism.

Dualism is the view that souls and bodies are radically different kinds of things, separable from one another,

independent from one another. Souls are immaterial, bodies are material. Plato’s Phaedo seems to offer a version

of dualism.

Materialism (properly speaking: reductive materialism) is the view that there are only material bodies of one sort

or another. If there are souls, they are to be identified with material bodies.

Aristotle rejects both of these options:

Now given that there are bodies of such and such a kind, viz. having life, the soul cannot be a body; for the

body is the subject or matter, not what is attributed to it. Hence the soul must a substance in the sense of the

form of a natural body having life potentially within it. (412a19-21)

In the case of living things, the body is the matter, and the soul is the form, the soul is the ‘form of a natural body

having life potentially within it’.

B. First comparison: body and soul are like wax and its shape.

…we can dismiss as unnecessary the question whether the soul and the body are one: it is as though we were

to ask whether the wax and its shape are one, or generally the matter of a thing and that of which it is the

matter (412b7-8)

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24.01: Classics of Western Philosophy

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This brings out the idea that soul is form, body is matter, and that you would not have the one without the

either—contrary to Plato, they are interdependent.

C. Second comparison: body and soul are like an axe and ‘the account of an axe’.

Suppose that a tool, e.g. an axe, were a natural body, then being an axe would have been its essence and so

its soul. (412b14)

This comparison brings out the idea that soul might be a certain kind of ability: what it is to be an axe (what is

involved in the account, or definition, of an axe) is to be able to cut wood. The form of an axe is not just a certain

shape (unlike the form of a statue), but a certain shape organized to do something. If the axe loses that ability, it

ceases to be an axe, except in name. But the ability to cut is not some mysterious invisible being, capable of

separation from the wood and steel of the axe. Likewise for the soul.

. Third comparison: body and soul are like the eye and sight.

Suppose that the eye were an animal—sight would have been its soul, for sight is the substance of the eye

which corresponds to the account, the eye being merely the matter of seeing; when seeing is removed the eye

is no longer an eye, except in name—no more than the eye of a statue or of a painted figure. (412b19-22)

This comparison brings out more vividly the idea that soul might be a certain kind of ability. The form of an eye

is not just a certain shape, but a certain power. Sight is the ability to see: and without that ability, there is no eye,

strictly speaking. But again, sight is not some mysterious, invisible being, capable of existing without the eye-jelly.

Likewise for the soul:

As the pupil [eye-jelly] plus the power of sight constitutes the eye, so the soul plus the body constitutes the

animal. From this it indubitably follows that the soul is inseparable from its body, or at any rate that certain

parts of it are (if it has parts)... (413a4)

So Aristotle provides an alternative to materialism and dualism.

. Forms of life

Soul is what makes something alive. But life brings different capacities in different sorts of things. Life in an

apple tree, or a dog, or a human, entails different abilities. Soul enables a living thing to fulfill the powers or

functions of that kind of thing, whether nutrition, movement, perception or thought. In fact, soul is identical to those

powers and functions. However, this does not mean that one is only alive if one is constantly exercising one’s full

capacities! That is because there are two grades or levels of capacities.

Now the word ‘actuality’ has two senses corresponding respectively to the possession of knowledge and the

actual exercise of knowledge.” (412a22).

This is all best explained with examples. Consider a human infant. We might say that an infant can speak Greek,

meaning that they have a capacity to learn the language. Once someone learns a language, they aren’t

constantly speaking, however. So we might say of someone sitting quietly that they can speak Greek. This

capacity is different from the infant’s capacity. Moreover, a person who can speak Greek in the second sense

might also be actively speaking Greek. This gives us three levels of potentiality/actuality:

i. First potentiality (1P): infant can speak Greek if they undergo certain significant changes (learning the

language)

ii. Second potentiality (2P)/first actuality (1A): quiet speaker can speak Greek if prompted to – the first

potentiality has been actualized, even if the speaker isn’t actually speaking.

iii. Second actuality (2A): person actually speaking Greek

Another way to put this: something at the 1P stage has a capacity for a capacity; at the 2P/1A stage is has that

capacity; and at the 2A stage it is exercising that capacity. Matter, in a sense, is pure potentiality; form is what

realizes that potential, but then brings along further potential.

This gives us the resources to understand the full definition of soul: “soul is the first actuality of a natural body

that is potentially alive. . . 412a27,” and again, “soul is the first actuality of a natural organic body” (412b5). The

soul of an apple tree brings apple tree capacities; the soul of a dog, dog capacities; the soul of a human, human

capacities. The exercise of these capacities makes us fully alive and fully who we are.

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