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Lecture 2: Aristotle

Plato and Aristotle stand out as two of the most influential--if not the most influential--philosophers of the Western tradition. Aristotle lived in an age of Greek expansion under Phillip of Macedon and Phillip's son, Alexander the Great. The death of Alexander in 323 BCE marks the end of the Hellenic period of Greek civilization, and the death of Aristotle the following year signaled the end of a "golden age" of Greek philosophy.

Aristotle was born in 384 BCE in Stagira (in Macedonia). When he was 17, he enrolled in Plato's Academy in Athens, and he distinguished himself as a student and later as a teacher there. After 20 years, Aristotle left the Academy, travelling and serving as tutor to Alexander. Twelve years after leaving the Academy (in 335 BCE), Aristotle returned to Athens and founded his own school, called the Lyceum. After the death of Alexander, anti-Macedonian sentiment in Athens forced Aristotle to leave the city. He went to Euboea, but died shortly after (in 322 BCE).

Aristotle and Plato

Aristotle was a student and colleague of Plato for twenty years, but there are striking differences between them. On the surface, we might characterize Plato as a "speculative" philosopher, concerned more than anything with a reality that transcends ordinary experience and life. Aristotle, on the other hand, was more of an "empiricist," and he concerned himself with detecting patterns in the world he found around us. Consequently, Aristotle may be credited with many "firsts": he seems to have written the first book in a number of disciplines that we now recognize and study, such as biology, meteorology, economics, aesthetics, and so on.

Though the apparent differences between Plato and Aristotle seem great, they have much in common. Watch for elements in Aristotle's "basic orientation" that are recognizably Platonic.

Aristotle's Basic Orientation: Categoriae

We will be looking at several excerpts from three books by Aristotle. The first of these, from the Categoriae (Of Categories) illustrates Aristotle's understanding of the "big picture," his basic orientation. Aristotle believed that, of all the ways we interact with the world, by far what we do most is talk about things. So, he seems to have thought that language provided our basic clues about the nature of reality. We start, then, with a theory of language--which he clearly intends as a theory of reality.

The first thing we notice about talking is that we sometimes say things in "complete sentences"; this Aristotle calls "combinations." These combinations, compared with "noncombinations," are most interesting, since the "complete sentences" are what allow us to claim something about the world. The easiest way to see this is to note his comment about combinations: when we join different elements together to form a combination, we are affirming something. Only affirmations can have a "truth-value." In other words, when we make an affirmation like "Matthew is obnoxious," it makes sense to ask whether it is true or false. Note that you need not be in a position to tell whether it is true or false; the point is that it is either true or false. Consider noncombinations: it does not make sense to ask whether they are true or false. Suppose I ask you, for instance, "True or false: thirty-seven miles from Austin?" You cannot give an answer, not because you don't happen to know, but because it doesn't make sense to ask whether that phrase ("thirty-seven miles from Austin") is true or false.

Now considering the ways we affirm something about the world, Aristotle claims that there are only two relations: said of and in. If we consider the possibility that some affirmation could be either a said of or an in or both (or neither!), we have four categories:

  1. said of but not in
  2. in but not said of
  3. both said of and in
  4. neither said of nor in

We can represent these categories in a table:

said of
but not in
both said of and in
neither said of nor in
but not said of

I am sure you have noticed that I have not explain what these relationships are. At this point, we were just trying to see the structure: this table has been nicknamed the "Ontological Square." (Aristotle didn't make up this table or the nickname; rather, this nickname was made up by the Medieval philosophers who systematized and elaborated Aristotle's philosophy after its rediscovery in the West.)

Now we need to see what Aristotle had in mind. He gives examples of the said of, such as "Matthew is a man" or Shamu is a whale" or "Lassie is a dog." We could extend this list and include things like "All humans are mammals," "Mammals are animals," or "Dogs are animals." In each case, the second term (like "man" or "whale" or "dog") is said of the first term ("Matthew," etc.). So, what is the relationship? What do all these have in common?

When I say, "Lassie is a dog," I mean that "dog" is the kind of thing that "Lassie" is. Similarly with "Shamu is a whale" or even "Dogs are animals." Aristotle thought that when we identify what kind of thing something is, we are saying what category it belongs in. Another way to talk about this relation, then, is "class inclusion." When I say the kind of affirmation that involves a said of, I am indicating what class something belongs in. So let's notice that box number 1 is going to include classes of things (that is, kinds). What does in mean?

The examples that Aristotle gives of in affirmations are a little harder to see for us. Obviously, he does not mean class inclusion, since said of and in must be two different relationships. Look at the examples: the example about "white" is most revealing. What does he mean when he says the white is in a subject? In this case, he means that, in a sentence like, "Matthew is obnoxious," "obnoxious" is in Matthew--but not in Matthew in the say that Matthew's liver is in him (that would be inside). Rather, this "obnoxious" is in Matthew in the sense that it is a quality or attribute of Matthew. So too with affirmations such as "That tree is tall": this particular trait "tall" is in the tree. So we can think of in affirmations as involving "attribution": saying what something is like.

Now notice that there is a very big difference between saying what something is and what something is like. The former tells us what category of thing something is, like "Matthew is a man." The latter, however, doesn't identify the kind at all; it just tells you what trait something has, whatever it is: "Matthew is obnoxious."

Now we understand boxes 1 and 2. Box 1 includes kinds and box 2 includes attributes. It is hard to see what Aristotle meant by box 3, things that are both said of and in. He apparently meant classes of attributes. Think of it this way. Suppose I say, "This tree is brown." This is an attribution: this brown is in this tree. But this brown also belongs to a certain kind, namely, "brownness"; likewise, brownness belongs to a certain kind, color; and so on. So obviously there can be kinds of traits, in addition to individual traits. That takes care of the first part, said of. Concerning the second part, in, Aristotle apparently believed that general terms like "brownness" or "color" had to be attributes of general things, like "body." So, we say "color is in body," meaning, "Color in general is an attribute of bodies in general." If this is confusing, you are not alone; philosophers have debated what Aristotle could have meant by this "said of and in" box for centuries.

This brings us to box 4, "neither said of nor in. Think of what we have said so far about boxes 1 through 3. Aristotle summarizes these boxes in the following way: In box 1 we find kinds, and everything in box 1 is ultimately said of something in box 4. In box 2 we find attributes, and everything in box 2 is ultimately in something in box 4. Box 3 includes kinds of attributes, which are either said of something that is in something in box 4, or is in something that is said of something in box 4. The point is, everything ends up in box 4. And Aristotle makes it clear that these things are fundamental when he says that if the things in box 4 did not exist, then none of the others (boxes 1 through 3) could exist either.

So what exactly are things that are neither said of nor in. It helps for us to remember what these terms mean. Things in box 4 are neither kinds nor attributes. In other words, they are individual concrete things--like Matthew, or each of you, or Lassie, or Shamu. Aristotle uses the term, primary substances to refer to things like this, and he uses the descriptive phrase "individual and numerically one" to indicate that these things have a special sort of unity and individuality. He elaborates this further when he points out that primary substances are unique in that they remain "numerically one" even though they change. Take Matthew, for instance. Each day I grow older, sometimes I get sick, sometimes I grow pale (in the winter!) and then get tanned in the summer. In each case, I undergo change, but these changes do not alter the underlying fact that I am still Matthew through it all.

You may be wondering what the point of all this is. Remember Plato's notion that the whole cosmos is a hierarchy of reality, a "ladder" going from least real to most real? Well, in the same vein, Aristotle has given us a "picture" of the cosmos, but there are some major differences. What is most real according to Plato? The ideal forms, like Tablehood and Manhood. These are the forms that make individual objects the kinds of thing they are. But what is most real for Aristotle? Individual, concrete things are most real, and furthermore, there would be no kinds (something like Platonic forms without those individual, concrete things. (And there would be no attributes without primary substances either.) So, in a way, Aristotle's "reality scale" is a reversal of Plato's. This is what I meant when I said that Aristotle seemed more interested in this world, the world of our ordinary experience.

Primary Substances and Causes: Metaphysics

Now that we have some idea about things in box 4 (primary substances), we need to differentiate the different types of primary substances we find in the cosmos and see what their relationships are to one another. Aristotle distinguishes primary substances into three types: "one changeless and two physical." Primary substances that are physical are those that have a material nature and therefore can change. Aristotle believed that matter is what gives individual things their potential: so anything that has a material nature will have potential, and anything with potential can change. Alternately, if something has no potential, then that thing cannot change. This all works on the presupposition that change is really a matter of "actualizing potential," which is really a commonsense notion, if you think about it. Consider locomotion: I put my book here on my desk, but it has the potential to move there. If my book had no potential to move, then it would be immovable.

So, these physical primary substances all have material natures and therefore can change. Of these, some are eternal and the rest are perishable. The perishable ones are those that "come to be and pass away," like Matthew and Lassie. Lassie did not always exist, nor will Lassie continue forever. On the other hand, from Aristotle's perspective, there were things in the cosmos that always existed and always would--things like the moon, the sun, and the other heavenly bodies. But the existence of eternal physical primary substances that continually change raises a problem: What keeps it all going?

Aristotle sought to answer this question by "working back" from our experience in the world to its (logical) origins. When we look around, we see motion all around us. Yet each motion is brought about by something, and that thing also moves. If it moves, then it also must have been moved by something. So the question is, what moves everything?

Aristotle believed that there could not be an endless series of movers moving each other, because, he argued, if the series were endless there would be no motion. This is an unusual argument, but maybe I can clarify his point with an analogy. Suppose you come into my office and notice that I am sitting at a table that is so long that you cannot see the other end. On the table I have a series of dominoes set up--just like when kids set up a series of dominoes and then knock over the first, which knocks over the second, etc. through to the last domino. The difference is that you cannot see the end of the series of dominoes set up on my long, long table. Naturally you ask what I am doing, and I reply that I am waiting to see if these dominoes in front of me will fall. I say, "Maybe you can help. Go down there are topple the last domino to get the series started." Now, if you think about this for a moment, if the series is finite (has a last one), then you will be able to start the series, in which case the dominoes in front of me will move (fall down). However, if the series is not finite (has no last one), then you will not be able to topple the last one and those in front of me will not move. (Unless you cheat and intervene somewhere in the middle of the series; but in that case you haven't done what I asked, namely, topple the last one.)

The moral of the domino story is simply this: if the series is finite, then the series will move, but if the series is infinite, the series will not move. This is because there must be an origin for the motion of the dominoes, there must be a "first."

Now let's change the story a bit. Suppose you come into my office and see the table as before, except that there is not a curtain hanging over the far end of the table just past where I am sitting. The curtain prevents you from seeing whether the series of dominoes is finite or infinite. As before, I am sitting there, staring patiently but intently at the series of dominoes before me on the table. We chat for a moment, and then we hear dominoes falling into one another. Through a tiny, domino-sized hole in the curtain, a domino falls, striking the ones we can see. The series falls, right before us. Now, was the series finite or infinite? Since we saw them move, and--on the conclusion we drew from the previous version of the story--they could not move if the series had been infinite, we now conclude that the series must have been finite. If it was finite, then there must have been a "first." But now we face an oddity.

The "first mover" of the domino series cannot have been an ordinary domino. It so, it would have moved only if something else moved it. But if is was the first, then there cannot have been anything else that moved it--or else that would have been first. So, the "first mover" of the domino series must be the sort of thing that moved the series without being moved by anything else. But anything that is not moved by anything is the sort of thing that cannot move. So, the "first mover" of the series is a "mover" that did its job of moving the series without moving. This is the reason Aristotle calls this being   the "unmoved mover" or "unchanged changer."

So, even though the line of argument in Book Lambda of the Metaphysics is difficult to follow, the gist of it is the "domino" argument: without a first mover, there would be no motion. There is motion, therefore, there is a first mover. (See the reductio again?) Further, a first mover that moved would not be first, so the first mover must be an "unmoved mover." This implies that the unmoved mover is changeless, and if so then it is also incorporeal (has no material nature).

Now, let's see why the unmoved mover must be an incorporeal being. If anything changes, it has a material nature, since the nature of matter is to confer potentiality. So something that does not change has no potential. If something has no potential, then it cannot have a material nature. Another way to say this is that the unmoved mover is purely actual. Being purely actual rules out having the potential to change, since something that is actual already is everything it is going to be. So the unmoved mover is eternal, but in a rather odd sense: time attributes do not apply to it. In other words, it is "transcendent" in the sense that it is "above" the flow of time. (The heavenly bodies, like the sun, are eternal in a different sense: they "last forever," but they are not above the flow of time.)

Aristotle's starting point for this argument about the unmoved mover was the question about how our world of changed is sustained. One question we have not addressed is how a purely actual being, one that does not change, is nevertheless able to "produce" all this change. Aristotle only hints at an answer: the unmoved mover is like the "desirable" or the "intelligible." He must mean something like this: Suppose you are at a party, and you see someone across the room that you find attractive. You gravitate in his/her direction. That person may have been completely oblivious to your existence, but nevertheless, s/he has "moved" you. How did this happen? The attractive one "moved" you just by being what s/he is. Likewise with the unmoved mover: it is a being that moves the cosmos just by "being."

So we now have a picture of the cosmos from Aristotle's perspective: the basic things are primary substances, on which all other categories of things depend for their existence. Moreover, in the world of our experience, we find that there are perishable primary substances (like you and me) and imperishable primary substances (like the planets and the sun). These move eternally, and their endless motion is explained by the unmoved mover--a being that "just is."

I included two other passages from the Metaphysics to get us ready to understand Aristotle's theory regarding the soul. In Book Delta, Aristotle discusses the four types of aitia, or "explanatory factors." The traditional translation of aition is "cause," and for this reason they are called the "four causes." Consider my house. If I want to explain the existence of my house, I might start by telling you who built it. Those who worked on the house "caused" it to exist, in a particular sense of "cause." The "maker" or the "doer" is the efficient cause. But they had to have concrete, lumber, sheet rock--in short, they had to have materials. In another sense of "cause," the materials caused my house. This type of cause is called the material cause. The workers (the "makers") also have to have a plan, something like a blueprint: this tells what the house will be like. This type of cause is called the formal cause. (Does this remind you of someone? Aristotle's formal cause is like an essence for that thing, more or less reminiscent of Plato's ideal forms.) In a sense, then, the plan also caused my house to exist. What else is there besides the plan, the materials, and the maker? In the case of my house, there is the reason it was built--its purpose. This type of cause, the final cause, answers the question, "Why?"

Aristotle believes that these explanatory factors (causes) can be invoked any time we are investigating the nature of something. Take me, for instance. The efficient cause is my parents; they "made" me. The material cause is the matter that my mother contributed. (This is Aristotle's view!) My formal cause is the "what-it-was-to-be-Matthew"--in other words, the "Matthew-essence" that makes the lump of matter a particular living human being, Matthew. And my purpose . . . . Well, I am here to realize myself, to exercise my capacities, and in so doing to become "happy." Aristotle has a complete theory of the purpose of human life, which he spells out in his Nicomachean Ethics. In fact, happiness, as he defines it, is the guiding principle for ethical decision-making. We must strive to be virtuous, because virtue is what leads to the realization of the purpose of human existence.

The Soul

At last we are in a position to see what Aristotle says about souls. I have given you a somewhat longer excerpt from De Anima (Concerning the Soul). Look for the themes discussed above.

Aristotle begins De Anima in his usual fashion: he reviews and critiques the theories of all his predecessors. We pick up the discussion in Book 2, which is just after this review. Aristotle "begins again," addressing the question, "What is soul?" He starts with substance, and concludes that soul cannot be substance in the sense of material cause. If it were then soul would be body. However, body is not life; it is what has life. So soul cannot be body, and hence is cannot be material. Since the body is material, it has the potential to be alive, and it is alive when this potential is actualized. But how is this potential-to-be-alive actualized? A body is alive when it is organized in a particular way. When he works out the implication of this, it comes to light that the soul is something like a formal cause. It is the essence that makes a living body what it is, namely, alive.

You may have noticed that Aristotle talks about plants and animals as having soul, in addition to human beings. Think about why this is: as living beings, soul explains why they are alive. Plants have a "nutritive soul" that allows them to take in nourishment in order to grow. Animals also have nutritive souls, but those that move around to seek their food must have sense organs (such as eyes and ears). Since they have sensation, they also have a "sensitive soul," which gives them the ability to sense their environment and move around. The human being as a "rational animal," possesses both nutritive and sensitive soul, to which is added the rational soul. As its name suggests, this give human beings their ability to "theorize" and reason about things.

Note that it is the organization of these different bodies that gives them these capacities; these types of souls are not "external" things "inserted into" a body. Rather, the soul is like a blueprint that details exactly what being that individual would be like. So my soul is the "what-it-was-to-be-Matthew"--a sort of blueprint of Matthew-ness. But my soul is not me any more than the blueprint of my house is my house. Only when the blueprint is actualized is my house the sort of thing I could live in; no one lives in a blueprint. This leads us to realize that the "real" Matthew is a composite of body and soul.

With all this in mind, we can see that the Aristotelian notion of the soul is very different from the Platonic soul. For Plato, my soul is the "true" me, temporarily housed in my body. And since my soul is incorporeal, the death of my body does not affect me. Aristotle rejects this view. Since the "real" Matthew is the living organism (emphasis on organized), when Matthew dies there is no more Matthew at all. Think about it. Even if the blueprint for my house were secure in a safe somewhere, if my house were destroyed, the house would be gone. so, even if the Matthew-essence is eternal in some sense, it is not me, and its continued existence does not guarantee that I continue after death. And in fact Aristotle did not seem to think there was any such thing as personal survival after bodily death. Death, according to Aristotle, is the end of life.


rediscovery: Aristotle's works were largely lost in the West after the collapse of the Roman Empire and the rise of Christianity. Platonism, and especially Neo-Platonism, absorbed Aristotelian ideas until the "rediscovery" of Aristotle in the 11th century. back

primary substances: We use the word "substance" in various ways, most of which are not what Aristotle has in mind. The term "substance" is the traditional translation of the Greek word ousia, which really meant "being." This makes more sense: things in box 4 are "primary beings," that is, the beings that must exist in order for any other beings to exist. So it helps if you remember the original meaning, "being." The most misleading use of "substance" is when we use it to mean "stuff" or "material." (For instances, "possession of illegal substances": it means "stuff," not "being"!) back 

Aristotle's perspective: Aristotle, and the ancient Greeks generally, believed that the cosmos was eternal. In other words, they did not believe that the world was created at a certain moment, or that the world could ever be destroyed. This is the origin of Aristotle's view that some material things are eternal in the sense that they last forever. back

just by being: In case you think this line of thought is silly (or if it sounded familiar), many Christian theologians have adopted Aristotle's line of thought to demonstrate the existence of God. Although Aristotle did think of the unmoved mover as a "divine being," he did not mean what Christians mean by the term "God." The term "God" means a person; that is why it makes sense to pray to such a being. It would make no sense to pray to the unmoved mover, not because it is not a transcendent, eternal, actual being (all those traits have been ascribed to God) but because it is not a person. back

life: Aristotle, like most Greeks, identified the soul as the "life-principle," i.e., what makes a body alive. In this he agrees with Plato, even though he differs considerably in his views regarding the nature of soul. back

survival: Aristotle seems to have recognized one component or aspect of soul that might survive, namely, the "active intellect," which is the aspect of our souls that allows us to exercise reason. So, for instance, when Matthew dies, the active intellect that was "in" his soul survives. However, this component is not Matthew: it has none of Matthew's experiences or memories, and it possesses none of the traits that the bodily Matthew possessed. It is, in fact, only Matthew's sheer ability to think rationally--which, incidentally is identical in all rational beings. back