Lesson 12: Rhetoric and Poetics


In this, our twelfth and final lesson, we will say something about rhetoric and poetics. In the first eleven lessons we looked at the treatises in Aristotle's Organon that make up logic taken in the strict sense: logic as the art which directs the actions of reason in coming to know the truth. But we also said there was a looser sense of that term "logic," in which logic is broadly understood to be the art that simply directs the actions of reason. Sometimes we reason about human actions. Rhetoric directs our reason when it considers moral and political actions. Reason also acts in poetry, or imaginative literature, to produce something beautiful and delightful. The science of poetics discusses this action of reason. Studying rhetoric and poetics completes our overview of Aristotle's logic. This lesson will focus on Aristotle's books, the Rhetoric and the Poetics.

There is another reason, however, for studying these two books. Some of the tools of reasoning that are most appropriate to rhetorical and poetical speech are also helpful for philosophy and theology. There are going to be three of those tools, two of them from rhetoric: the enthymeme and the argument by example. The third comes from poetics: the metaphor. In this lesson we will look at rhetoric and poetics especially to consider those tools. We can break up our discussion into two parts. In the first part we will talk about the main rhetorical tools, the enthymeme and the example. In the second we will talk about the main poetic tool, the metaphor.


In order to understand what is going on in Aristotle's Rhetoric, first we are going to take a broad overview of the subject, secondly we are going to focus on the two tools of the enthymeme and the argument by example.

At the beginning the Rhetoric, Aristotle explains what rhetoric is by a comparison with dialectic. Rhetoric and dialectic share three main features. First, both the rhetorician and dialectician can argue on both sides of an issue. The dialectician, we saw, wants to defend his side and attack the other, but he may be pitted against a dialectician who is doing the same thing. Then both of the opponents in a dispute are using the dialectical power. Thus the power of dialectic is a power to argue both sides of an issue. The same is true in rhetoric. When two orators oppose each other on some course of action, they both use rhetorical arguments to try to persuade their audience. Like dialectic, rhetoric is a power that can be used on either side of an issue. On contrast, the demonstrator can argue only for one side of an issue. There is no geometrician who is going to give a proof contrary to Euclid's demonstration that the angles of a triangle add up to 180 degrees. Euclid's proof settles the matter. There is no opposing demonstration.

Second, both the rhetorician and the dialectician are able to argue about any subject whatsoever. A dialectician can argue about natural science, about metaphysics, or about ethics. It would be strange, but not unheard of, for even a rhetorician to argue about natural science and metaphysics. In this way, both differ again from the demonstrator. The geometer demonstrates about geometry, but as geometer he has nothing whatever to say about natural science or metaphysics or ethics. Again, only the metaphysician gives demonstrations about metaphysics and only the man who knows ethics can demonstrate in ethics. Thus, both rhetoric and dialectic differ from demonstration because they are powers to argue about anything. A corollary of this conclusion is that the tools a rhetorician uses, or at least some of them, can be applied to many different philosophical disciplines.

Third, both the dialectician and the rhetorician achieve only a probable conclusion, not a certain one. When we talked about the difference between rhetoric and dialectic before, we noted that the dialectical conclusion is stronger, is more often true, or is at least closer to the truth than the rhetorical conclusion. But in contrast to the demonstrator, neither the dialectician nor the rhetorician reaches his conclusion with certainty. Thus, rhetoric and dialectic seem superior to demonstration in that each can argue both sides of an issue and can discuss anything, but ultimately both are less perfect than demonstration because their conclusions are only probable.

There are, however, important differences between rhetoric and dialectic. First, the dialectician and rhetorician have different ends or goals. The dialectician is aiming remotely at some sort of knowledge. By his argument he cannot come to complete certainty, but he can come to have pretty good reasons for holding one side of an issue, and he can use this as a stepping stone to demonstration. The rhetorician is not so much interested in coming to know as in persuading his audience. And he does not want to persuade them simply to hold an opinion. Rather, he wants to persuade them to act in some specific way because they hold that opinion. For example the dialectician might ask the question whether God exists, and he might come up with several good dialectical arguments that strongly incline him to believe that God exists. The rhetorician might also talk about the existence of God, but he talks about the existence of God in order to persuade people to behave virtuously.

Second, because the dialectician and rhetorician have different purposes for their activities, they appeal to different kinds of audiences and use different kinds of arguments. That is, the discourse of the dialectician about the existence of God is addressed to men who are relatively wise, men who have a philosophical inclination and some philosophical experience. Therefore the dialectician tends to use abstract, universal arguments. The rhetorician, however, wants to persuade people to lead virtuous lives. He wants to persuade, not only those who are already philosophically inclined, but everyone. So his arguments cannot be as abstract and universal. They have to be more concrete and particular because the concrete and particular are easier to understand.

Third, since the rhetorician wants to move people to action, he legitimately appeals to their emotions in his arguments. In contrast, the dialectician, since he does not aim at action, does not legitimately appeal to emotion. For example, the dialectician simply presents the arguments for the existence of God, while the rhetorician points out that a universe without God is appalling to people of good dispositions. The dialectician brings in argument only, while the rhetorician brings in both argument and emotion.

The Tools of Rhetoric: Enthymeme and Argument by Example

Since the rhetorician is arguing for the many, and not for the few wiser people, he is going to use logical tools which are more understandable to the beginner, even though such tools are most often less perfect and achieve less certainty. But precisely because they are more understandable by the beginner, they are very useful in philosophy, which is a difficult subject, one whose students need all the help they can get. In fact, the tools which are characteristic of the rhetorician are yet tools that Aristotle and St. Thomas use when dealing with philosophy and theology. Those tools are the enthymeme, and the argument by example.

Aristotle does not define the enthymeme and argument by example. He simply says that an enthymeme is a rhetorical syllogism, and an example a rhetorical induction. But he compares and contrasts the enthymeme with the syllogism, and the example with the induction. We will follow his lead. First, we will look at how the enthymeme and example are respectively like the syllogism and the induction. Then we will look at how they are different. Finally, we will offer something like a definition of each.

Let us first look at the likeness between the enthymeme and the syllogism. When we talked about the form of the syllogism, we said that every syllogism had to have a universal proposition. It was only because at least one of the propositions was universal, at least one of the predicates was said of all or none of its subjects, that any sort of necessary reasoning could take place. And from that universal premiss, a less universal conclusion is usually drawn. The following is a typical syllogism.

Every animal has sense desires.
Some living things are animals.
Therefore some living things have sense desires.

This syllogism began with a universal statement, every animal has sense desires, but ended with a more particular statement, some living things have sense desires.

Just as the syllogism begins from a proposition which is more universal, and concludes with one that is less universal, so also the enthymeme begins with something that is more universal, and concludes to something less universal. Take the following enthymeme:

The harder good is the better good.
But virtue is a harder good thing to acquire than pleasure.
Therefore virtue is a better thing than pleasure.

It begins with a more universal principle, "the harder good is the better good," and concludes to a more particular conclusion, "virtue is better than pleasure." Thus the enthymeme and the syllogism are alike because both begin from the more universal and conclude to the less universal.

Let us next consider the likeness between example and induction. Take the following induction:

Fido barks.
Spot barks.
Rover barks.
Therefore, all dogs bark.

Notice that it begins with particular statements, statements about individuals. The same will be true with the argument by example. Aristotle gives the following instance of an argument by example: Like the induction, this argument by example begins with statements about particulars. It begins by reciting particular facts about Peisistratus, Theagenes, and similar rulers. The argument by example is like an induction because it begins with particular statements. That is why Aristotle calls the enthymeme a rhetorical syllogism and the argument by example a rhetorical induction.

In the past, Peisistratus asked for a bodyguard, in order to make himself a despot, and so did Theagenes at Megara; and in the same way all other instances known to the speaker in which a ruler asked for a bodyguard, he desired to become a despot. Therefore, when Dionysius now asks for a bodyguard, he has the same purpose, to become a despot.

Let us now consider the difference between the enthymeme and the syllogism. Just as a demonstration differed from a dialectical syllogism because it had different kinds of premisses, so the enthymeme is going to differ from every kind of syllogism because it has a different kind of premiss. Aristotle writes:

Now the materials of enthymemes are probabilities . . . A probability is a thing that usually happens; it bears the same relation to that in respect of which it is probable as the universal bears to the particular.

The enthymeme differs from the syllogism because a syllogism always has at least one completely universal premiss. That premiss may be false, but it is taken as completely universal. In contrast, the enthymeme starts from a probability, a premiss which is fairly, but not completely universal, in which something is true most, but not all, of the time. Since the premiss is not truly universal, the conclusion of an enthymeme does not necessarily follow from the premisses.

For instance, the syllogism which we gave above premissed that "All animals have sense desires." Our enthymeme premissed, "The harder good is the better good." But the latter statement is not true universally. The harder good is not always the better good, but rather there are cases in which the easier thing to do is also the better thing to do. That statement is only true most of the time. That kind of premiss does not have the universality that is required for the syllogism, but it is the appropriate material for an enthymeme because the enthymeme has a conclusion that is less certain than that of the syllogism. We might modify Aristotle's definition of the syllogism and apply it to the enthymeme: in an enthymeme, certain fairly universal premisses being given, something else probably follows from them.

Let us now see how the argument by example differs from induction. In an induction, the conclusion, though probable by the form of the induction, is universal. Our illustration of induction concluded that all dogs bark. But the argument by example comes to a particular conclusion. Our illustration of it concluded that Dionysius asked for a bodyguard in order to become a despot. But that conclusion is about an individual, not about a universal. The argument by example differs from induction because it comes up with a particular or individual, not a universal conclusion.

Let us sum up with conclusions with a couple of definitions. We can define the enthymeme as a process of reasoning which begins with what is true for the most part and reaches a more particular conclusion that is probably true. And we define the argument by example as a process of reasoning which begins with particular premisses and ends with a particular conclusion.

We can now see why both of these tools are appropriate to rhetoric. Rhetoric is supposed to move men to action. Since we need only reasonable probability in order to act, an enthymeme is practically just as good as a syllogism, and even better because it is more easily understandable. Furthermore, actions are about particulars. The argument by example, which comes to a conclusion about a particulars, is thus more fitting than induction. And since the particular concrete individual is easier to grasp than the universal, the argument by example is also easier to understand than induction. The enthymeme and example are appropriate tools for rhetoric.

But these tools have a certain use in philosophy as well. First, we should note that philosophy is a very difficult subject in which the beginner can use all the help he can get. The first arguments that he will understand are not demonstrative, nor even dialectical. Syllogisms and even inductions are beyond him. What is proportionate to him are enthymemes and arguments by example. Furthermore, there are some philosophical subjects which do not admit of a lot of certainty. Ethics and political philosophy, because they are less certain than mathematics or metaphysics, often must rely on arguments whose forms are less certain than the form of the demonstration or even the dialectical syllogism. If you study Aristotle's Ethics or Politics, you will see that he very often uses enthymemes and arguments by example. Thus the tools of rhetoric are also useful for philosophy.

Poetics and Metaphor

We have one more tool to talk about, the tool of metaphor, which is found in Aristotle's book called the Poetics. The Poetics is more often studied in a literature course, because it gives a theory of how imaginative literature works. We are not going to worry about the famous definition of tragedy and the catharsis of fear and pity. Rather we will discuss two points. First I will point out why we need to study a poetic tool when we are talking about philosophy and theology. Second, I want to study that poetic tool, the metaphor.

In the first question of the Summa Theologiae, St. Thomas asks whether metaphor should be used in Sacred Scripture. One of the objections states that, because theology and poetry are so different from each other, they cannot have the same tools. Since poetry clearly uses the tool of metaphor, theology should not. St. Thomas grants that poetry and theology are far distant from each other. But they are distant from a middle, and it is precisely because they are both so distant from that middle that they can use the same tool. That middle consists of things that are readily understandable by human reason. Mathematics is the prime example of this, but natural philosophy and metaphysics are also subject proportioned to human reason. They all deal with universal truths which are derived from sense experience. Reason grasps the universal but is rooted in sensation. Thus these sciences are proportioned to reason.

Literature, however, is outside of the rational realm because it deals with singular actions. For instance, a novel is not about the universal nature of man but about particular people doing particular things in a particular time and place. Literature, then, deals with something that is below reason, but that instead falls mostly under the province of the senses, which perceive the particular and the individual. Theology, on the other hand, is outside of the rational realm, not because it is lower than reason like literature, but because it is so far above reason. That is, while God is not a concrete individual, He is also not something that can be understood very well from what we derive from the senses. The Divine Nature is so far above us, that our reason, rooted as it is in the senses, cannot grasp it. And thus, St. Thomas points out, there is a common tool which reason uses to try and grasp anything that is disproportionate, whether that this is below it or above it. That tool is the metaphor.

Aristotle in his Poetics defines the metaphor very simply.

Metaphor is giving a name to something that does not belong to it, but belongs to another thing.

Shakespeare gives a very famous metaphor in Romeo and Juliet. Romeo says:That is, Shakespeare gives the name "Sun" to Juliet. Juliet is the Sun. That name does not belong to Juliet. "Sun" is a metaphor for Juliet because, just as the sun is necessary for the life of all living things, so also Juliet is necessary for the life of Romeo.

But soft, what light through yonder window breaks? It is the East, and Juliet is the sun.

The purpose of the metaphor is to make known to us a surprising likeness between unlike things. The poet uses the metaphor because it is surprising and therefore pleasant. We like it when Romeo calls Juliet the sun because we are surprised that there is a likeness between the sun and the object of our love. Holy Scripture will use the metaphor, not primarily to give us pleasure like the poet does, but to make something known to us about God. The Scriptural metaphor points out a likeness between the creatures that we understand fairly well and the God who is so hard to understand. For example, Scripture calls God a rock. Literally speaking, God is not a rock, but the author of Scripture wants to convince us that, like a rock, God has stability, permanence, and endurance. And so the writer of Scripture makes known to the reader something about the nature of God using the metaphor which points out a likeness between God and creatures.

We might be tempted to confuse metaphor and analogy, but they differ in two ways. First, to say that a term is used analogously is to say that it is used twice and has two different but related meanings. A term used metaphorically need only be used once and it retains its common meaning. Second, the statements which use a term analogously state that the term actually belongs to both subjects, while the statement which uses a term metaphorically does not really state that the term actually belongs. For example, we said earlier that rhetoric is both part of and not part of logic. That is because we have given the term "logic" two different meanings, one of which truly includes rhetoric, the second of which truly excludes it. When we say "Juliet is the Sun," the word "Sun" retains its first meaning but the statement is not meant to imply that the predicate truly belongs to the subject. It only means to point out the likeness between the subject and the predicate in a striking way.

We have talked about three tools of the lesser parts of logic: the enthymeme, the argument by example, and the metaphor. Though those tools are very weak tools and do not yield much certainty, they are very important to us, because of the weakness of the human mind almost more necessary to us than the syllogism. The human mind needs weak arguments like these before it can use the stronger ones.

Conclusion to the Course

I would like to finish by talking about what I hope that you can get from this logic course. There are, I think, three reasons why this logic class is important. First, from this class you should understand something of what philosophers and theologians are talking about when they use logical terms. Perhaps before the course you did not know what St. Thomas or Aristotle meant by genus, species, and difference. Now you do. Perhaps before you did not know what St. Thomas meant when he said that names are used analogously of creatures and God. Now you do. Perhaps before you did not know what exactly the word "syllogism" meant. Now you do. Just knowing what these terms mean should help you to understand better the philosophers and the theologians.

But I also hope that you will be able to use the logical tools themselves to understand the philosophers and theologians when you are reading their works. That is, you do not really understand a philosophical text unless you understand its logical structure. It makes a difference whether a theologian is using a syllogism that is meant to conclude with certainty or an enthymeme that concludes with probability. St. Thomas' own commentaries on Aristotle outline the logical structure of those books. He will write, "First Aristotle gives a syllogism; second, he gives an argument by example; third, he gives an enthymeme." I think that the tools covered in this course could be an important aid to your reading the philosophers and theologians with understanding.

Finally, I think that if you do the exercises that go along with this course, and get some practice in using these logical tools, your own thinking and your own writing will be improved. You will not only write and think with more force and certainty, but you will write in such a way that you will use the lesser tools like example and enthymeme in order to appeal to the beginners. Your thinking will become clearer and your writing will become an effective teaching tool.


1. Construct four good arguments on the same subject. Make one a syllogism, the second an induction, the third an enthymeme, and the fourth an argument by example.

2. Identify whether the logical tool of discourse used by the author: syllogism, induction, enthymeme, argument by example, fallacy of equivocation, or fallacy of the accident. 

Courage, when it is not wisdom but like a kind of recklessness, is harmful. The same is true of moderation and mental quickness; when they are learned and disciplined with understanding, they are beneficial, but without understanding they are harmful. Therefore, all that the soul does and suffers, if directed by wisdom, ends in happiness, but if directed by ignorance, it ends in the opposite. (Adapted from Plato, Meno, 88b - c) 

The hare and the tortoise may differ in the quality of swiftness, but they must agree in the quality of motion. When we say that the hare moves faster, we say that the tortoise moves. Thus, even in the act of saying things change, we say that there is something unchangeable. (Chesterton, Heretics

If then virtue is something in the soul that is always beneficial, and all the qualities in the soul that are always beneficial are wisdom, then the argument seems to show that virtue, being beneficial, must be wisdom. (Plato, Meno, 88d) 

God's ability is pure, not tainted with any lack of ability. But prime matter is also pure ability, that is, pure potentiality. Therefore, God is prime matter. (David of Dinant, see St. Thomas, Summa Theol. I, q. 3, art. 8, co.) 

To take a thing and make a joke out of it is not to take it in vain. . . . To use a thing in vain means to use it without use. But a joke may be exceedingly useful. (Chesterton, Heretics

Just as in the law courts no man can pass judgement who does not listen to the arguments from both parties, so must a person whose task is to study philosophy place himself in a better position to reach judgment by listening to all the arguments. (St. Thomas Aquinas, Commentary on Aristotle's Metaphysics, Book III, lect. 1, n. 342) 

America and Australia are new nations, and thus are vigorous, vital, and hopeful nations. (adapted from Chesterton, Heretics).


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