Spring, 1997. Swarthmore College Honors Essay for a minor in philosophy.
Brian Schwartz, 1997.
How can we explain how a thing behaves? For Aristotle, knowledge of something that does X answers the question: "On account of what does it X?" These explanations will evoke a cause, one of four types, of the entity in question. I will show that Aristotle considers the cause of a living thing's actions to be the soul: not as a material cause, but as a final, formal, and efficient cause.
Essential to understanding the four causes is knowledge of Aristotle's concept of a thing's nature. Aristotle speaks of two types of objects: natural and artificial. Natural objects contain within themselves a "source of change or remaining unchanged." Natural objects, in Aristotle's terms, are "due to nature," and "constituted naturally" (Phys. II.1 192b10-25). Unnatural, or artificial objects, have no innate tendency to change. Artificial objects have a tendency to change only to the extent that they are constituted of natural objects.
Aristotle arrives at a definition of nature as "a sort of source and cause of change and remaining unchanged in that to which it belongs primarily of itself, that is, not by virtue of concurrence." By change, he means motion, growth and decay, or alteration. Aristotle illustrates his concept of concurrence with an example of a doctor who heals himself by using his medical knowledge. He was the "cause of health in himself," yet he could have been healed had he not been a doctor. The man's being a doctor and being healed are concurrent, or "separable" attributes of the person (192b10-27).
Aristotle cites one common use of the term "nature": "the primary underlying matter in each case, of things which have in themselves a source of their movements and changes." In this case, the nature of an object is the material of which it is made (193a28-30). Yet, says Aristotle, matter is not sufficient to be the source of change or remaining unchanged. Nature can also refer to "the shape and form which accords with a thing's account" (193a30). If matter is the nature of a thing, then two things of the same material and different form have, by definition, the same nature. Yet these two things can behave in different ways, i.e., change or remain unchanged, not due to their matter, but due to their shape and form. For example, as Nussbaum (1992) wrote, to know whether one can throw a ball through a hoop depends on knowing the form of the two things, their radii, but not their matter. Hence, matter can not be the nature of a thing.
Aristotle writes that "form has a better claim than the matter to be called nature. For we call a thing something, when it is that thing in actuality, rather than just in possibility" (193b8). For example, what flesh and bone are made of lack the Physical properties of actual flesh and bone, but only this material can become flesh and bone (193a35-7). As shown below, this argument applies to his view that an organism's form, rather than its matter, is its nature.
What we call propositions or statements, Aristotle calls predications. Propositions, as we learned in grade school, have subjects and predicates. Aristotle calls the subject of a predication a substance (ousia), and attributes are predicated of it in the statement's predicate. Substances are existents, and to exist is to be something: A substance is the attributes that can be predicated on it. Someone has knowledge of something if he can answer the question about the thing: On account of what is a predication about a substance true? To know the answer to this question is to know the "primary cause" of this thing (Phys. 194b15-20).
The four causes of something are its matter, its form, its nature, and its end. A thing's nature is defined above, and is the "efficient cause," or "the thing which effects the change" (198a24). If the cause of an attribute is an end, then that attribute is what "something is for," and the cause is the "final cause." Aristotle gives the example of a person who walks to achieve an end of keeping fit (194b25-35).
The four types of causes are sufficient to explain how an existent changes. Each answer a specific question:
Something can have more than one cause; each is the cause of a different attribute of the substance. Aristotle uses a bronze statue as an example, where the bronze is its material cause, and statue-making its formal cause (195a5-10). The cause of the statue's melting at a certain temperature is its material cause. The cause of the statue's being displayed in a museum (rather than being used as an ash tray) is its formal cause.
The answer to the question: "On account of what is a living body different from a dead body of the same species?" is the thing that makes the living body living: its soul (psyche ). Whatever is cause of the attributes of living things, in virtue of their being alive, Aristotle calls the soul. As Aristotle writes, "living is the being of living things, and the soul [is] the cause an principle of this" (DA II.4, 415b). For example, the number of bones in a human body is not caused by the soul, as the body has the same number whether it is alive or dead. The soul does not account for this kind of attribute. Hence, the soul is the cause of the body's animation. Given Aristotle's four types of cause, what type of cause is it?
Aristotle considers causality as applied to nonhuman organisms in Physics II.8. He assigns two causes to the nest making of swallows, web spinning of spiders, leaf making and downward root growth of plants. The cause of these attributes is an end, i.e., these organisms have such attributes to achieve a goal. In this case, the cause is bird's protecting its young, the spider's capturing food, and the plant's protecting its fruit, and attaining nourishment, respectively. These organism's attributes are also due to their nature: their matter and form (199a).
These natural things behave in ways that are "both due to nature and for something." In this context, Aristotle writes that since the formal aspect of a thing's nature (the form) is an end, "and everything else is for the end, the form must be what things are for" (199a, trans. Irwin and Fine). Apostle has translated the second part of the above phrase as "form would be a cause in the sense of a final cause." As Aristotle writes "A thing's form or what it is, for that is its end and what it is for" is a "source of natural change" (198a36-b3).
In ascribing an end to the actions of living things, Aristotle sets himself apart from Empedocles, who holds the activities of living things to be accidental rather than teleological. For Empedocles, their activities are like that of the money lender and borrower who happen to meet in town and settle their debts when neither went to town for that purpose (196b30, 198b17). The cause of their meeting was not for the purpose of settling a debt; the meeting was accidental. Empedocles holds that the life-sustaining actions cited above occur by material necessity rather than "for something" (cf. Meyer, 1992). The roots of plants grow down while the rest grown up, says Empedocles, because of their respective materials, earth and fire (DA 416a). Aristotle rejects this view because it does not explain what holds the plant together, as the fire and earth move in different directions. "If there is such a thing, this will be the soul, and this will be the cause of its growing and being nourished" (416a). Here, Aristotle has rejected a view that evokes a material cause of an organism's activities. As M.F. Burnyeat writes, "For Aristotle it is the existence of life which explains why animals have the Physical constitutions they do, not the other way around."
Earlier in De Anima, Aristotle shows his disapproval of ideas that the principle of animation is material. According to Aristotle, his other predecessors (Democritus, Leucippus, the Pythagoreans, and Plato (Timaeus )) thought the soul to be the source of an organism's movement by causing itself to move. That the soul can move implies that it is material, and hence a material cause (DA I 403b, 406b).
Aristotle devotes much of De Anima I presenting and showing the nonsensical implications of theories that posit a self-moving soul to cause an organism's actions. Aristotle relates these views to his own by saying that they both regard the body and soul relationship to be like that of a boat and its oarsmen: the latter is the source of the former's motion. The source of the motion is carried with what moves (406a). For Aristotle, rowers are able to propel their boat "through some kind of choice or thought process," rather than moving themselves (406b).
The views of the soul-as-material also fail because they neither tell how the soul and body interact, nor why. Such theories allow "any old soul to be inserted in any old body, whereas in fact each body seems to have its own distinctive form and shape" (407b, trans. Irwin and Fine). A bad match of soul and body is akin to trying to play an 8-track tape with a CD player.
Empedocles, Plato, Democritus, Critias, and Hippo claimed the soul to be a material composed of the elements (405, 406b). Those claiming the soul to consist of an element or elements did so, says Aristotle, because they believed that a soul must be composed of the elements the things is made of to know of them (405b, 410a). On this "knowledge of like by like" premise, the soul must contain all things, as "each element will perceive its like, but there will be nothing to perceive a bone, say, or a man, unless they are in the soul, too." This theory also allows for the possibility for all things to have soul, as they are all formed from elements, and hence can know of their constituent elements (410a,b).
As shown above, Aristotle rejects past notions that the soul is material, and the implication that it is a material cause. His most succinct refutation comes not through analysis of his predecessor's views while accepting their premises, but in De Partibus Animalium:
"At any rate [Democritus] says it is clear to everyone that the human form (morphé) is, on the assumption that a human being is known by his figure and color. However, a dead human being has the same shape and figure that the living human being has, but is still not a human being." (640b30-35, cf. Nussbaum, 1978)
This argument stems from the same premises Aristotle uses in Phys. II 193a. Just as bed frames, flesh, and bone are not what they are in virtue of their matter, the nature of an organism is not its matter.
In De Anima II.1, Aristotle describes the nature of the soul. He cites substance (ousia) as one classification of existents. The things that are substance can be classified as matter, form, or a combination of matter and form. Matter is potentiality, form is actuality. Matter, writes Aristotle, "is not in itself a particular thing" (412a), but becomes one when it acquires form. As Irwin and Fine (1995) write of form (eidos), "The form is predicated of the matter, and is the formal cause." The matter of composite substances limits the potential of what attributes these things can actually be. For example, one can not make a wooden picture frame that does not burn because the material of this composite substance is flammable.
Of all existents, Aristotle writes that bodies "are most believed to be substances" (412a). A body can be natural or artificial, the latter made from the former. Organisms are natural bodies that grow, decay, and nourish themselves. They are living natural bodies. Aristotle classifies organisms as composite substances, i.e., those with both matter and form. The body of an organism is its matter, and the "soul is the substance as the form of a natural body which potentially has life, and since this substance is actuality, soul will be the actuality of such a body" (412a).
To explain how the soul is a "substance in actuality," Aristotle discusses the difference between a someone's knowledge of something and his attending to this knowledge. Just as possessing knowledge of the thing is a prerequisite for contemplating something, a natural body's possessing a soul is a prerequisite for its living. Aristotle calls this prerequisite a "first actuality," and arrives at a definition of the soul: the first actuality of a body is potentially alive. Aristotle explains that if eyes and axes were living things, sight is the soul of an eye and cutting is the soul of an axe. Sight and cutting ability make eyes and axes what they are: organs of sight and tools for cutting. The soul is what makes an organism what it is, a living natural body (412b).
For Aristotle, an eye is pupil and sight, an axe is handle+blade and cutting, and an animal is body and soul. The material of something and its functions are inseparable. From the above analogy we can see that an organism's soul is the activity of its matter, i.e., biological functions (Irwin and Fine, 1995, and Nussbaum, 1978). Hence, since the soul is the cause of living things, and to know the cause is to explain a predication on an organism. The activities of matter, not matter itself (as discussed above), is sufficient to explain the activities of living things.
We can now deduce from Aristotle's discussion of a thing's nature, types of causes, and the soul, that the soul is the formal cause of a living thing. "The soul is the form of a natural body that is potentially alive" (DA 412a). One type of cause is the formal cause (Phys. II.3 195a). Since the soul is the form of an organism, and one type of cause is form, then the soul is the formal cause of the organism.
Recall also that something's form, rather than its matter, is its nature (Phys. II.1 193b). The nature of a thing is the cause of its changing or remaining unchanged (Phys II.1 192b, Phys. II.3 195b). Since the soul is the form of an organism, and the form of something is its nature, the soul is the nature of an organism: the source, or agent, of an organism's changing or remaining unchanged. A substance's efficient cause is its nature, so the soul is the efficient cause of an organism.
When speaking of the activities of birds, spiders, and plants (Phys. II.8), Aristotle concludes that the end of their actions is what the organisms are, their form. Since the form of a living thing is its soul (DA II.1), the soul is the end for which living things act. Since the final cause of something is that for which it acts (Phys. II.3), the soul is the final cause of living things.
Aristotle states the conclusions of the above deductions in De Anima II.4:
"The soul, then, is the cause and principle of the living body, and as these are talked of in several ways, so is the soul the cause of the body in the three ways we have distinguished; for it is the cause as that from which the movement itself arises [efficient cause], and as that for whose sake it is [final cause], and as the formal substance [formal cause] of ensouled bodies." (415b)
He has established that the soul is the efficient, final, and formal cause of living things.
In De Anima II.4 Aristotle makes explicit how the soul is the efficient and final cause of organisms. Following his idea in Physics II.8, Aristotle cites the body of an organism as an agent of the soul: "The soul is the reason for the body as that for which it is." Here, the soul act is an efficient cause, the agent of the body. That is, the bodies of living things are "the soul's instruments." Since the soul is the formal cause, an organism's body also exists "for the sake of the soul....that for the purpose of which and that for whose sake" (DA 415b). Given this relationship between body and soul, and that the soul is the final, formal, and efficient cause of an organism, what has Aristotle added to our knowledge of living things?
To have knowledge of living things we must be able to give an account of their actions: to know the cause. In De Anima, Aristotle strives for this knowledge as he answers the question: "On account of what does a living thing act as it does?" Their actions are not accidental. Instead, organisms "do whatever they do in accordance with their nature," for the sake of reproduction "so that in the way that they may partake in the eternal and the divine." Reproduction as part of an organism's "nutritive faculty[,] which is the first and most general faculty of the soul....[This faculty's] functions are to reproduce and to handle nourishment" (DA 415a,b). In other words, an organisms act to sustain their own existence, which is a means to the end of reproduction. Whether this view applies to humans is a matter of great debate, and is clearly beyond the scope of this work.
Aristotle. De Anima. Trans. H. Lawson-Tancred. New York: Penguin Books, 1986.
______ . De Anima. In Aristotle: Selections. Irwin, T, and G. Fine, eds. trans. Indianapolis: Hackett Publishing Company, 1995.
______ . De Partibus Animalium. In Aristotle: Selections. Irwin, T, and G. Fine, eds. trans. Indianapolis: Hackett Publishing Company, 1995.
______ . Metaphysics Z. In Metaphysics Books VII-X. Trans. M. Furth. Indianapolis: Hackett Publishing Company, 1985.
______ . Physics. In Aristotle's Physics: books 1 and 2. Trans. W. Charlton. New York: Oxford University Press, 1970.
Burnyeat, M.F., "Is an Aristotelian Philosophy of Mind still Credible?" In A.O. Rorty and M. Nussbaum, eds. Essays on Aristotle's De Anima. Clarendon Press: Oxford, 1992.
Irwin, T, and G. Fine, eds. trans. Aristotle: Selections. Indianapolis: Hackett Publishing Company, 1995.
Meyer, S.S. "Aristotle, Teleology, and Reduction," The Philosophical Review, 1992.
Nussbaum, M. "Aristotle on Teleological Explanation." In Aristotle's De Moto Animalium. Princeton: Princeton University Press, 1978.
Randall, J.H. Aristotle. New York: Columbia University Press, 1960.