Chapter V: Book I: surveys by definition and division the opportunity

of the public speaker_. (i) Rhetoric is the complement of
logic (dialectic). It is the art of persuasion formulated
by investigating the methods of successful address; and
its object is to promote a habit of discerning what in any
given case is essentially persuasive. Proof as contemplated
by rhetoric proceeds by such means as may be used in public
address. Instead of the syllogism, which is proper to
abstract logic, rhetoric typically uses the enthymeme, that
approximate syllogism which is proper and necessary to the
actual concrete discussion of public questions. Thus rhetoric
serves as a general public means (1) of maintaining truth
and justice against falsehood and wrong, (2) of advancing
public discussion where absolute proof is impossible, (3) of
cultivating the habit of seeing both sides and of exposing
sophistries and fallacies, and (4) of self-defense. (ii) The
means of persuasion outside of rhetoric (πίστεις ἄτεχνοι) are
witnesses, documents, and other evidence; the means within
the art of rhetoric (ἔντεχνοι) are the moral force of the
speaker, his adaptation to the disposition of the audience,
and his arguments. (iii) The three fields of rhetoric are: (1)
deliberative address to a popular assembly, discussing the
expediency of a proposal for the future; (2) forensic address
to a court, discussing the justice of a deed in the past; and
(3) panegyric, commemorating the significance of a present
occasion. The eleven remaining chapters of this book analyze
each of these fields in its main aspects, or fundamental
topics, _e.g._, wealth, happiness, government, crime, virtue,
etc.[2]

The bare digest will show that Aristotle’s _Rhetoric_ is hardly a manual. In fact, it is rather less a manual than is his _Poetic_. It is a philosophical survey. The scope of rhetoric is measured not by any scheme of education, but by the relations of knowledge to conduct and affairs. To be comprehended, this great work should be read consecutively, for it is not merely systematic; in spite of parts undeveloped, it is progressive, and its chief significance, perhaps, is from its total development. The following discussion presupposes a fresh and consecutive reading.

About rhetoric Aristotle would first of all have right thinking, conceptions large enough to be suggestive and distinct enough to be true. So the definition in his first chapter is slowly inductive. First we are to distinguish rhetoric from logic.[3] As modes of thought the two are alike general, both applicable universally, neither having its own subject-matter. As modes of utterance they differ typically in that while logic is abstract, rhetoric is concrete; while the one is analytic, the other is synthetic; while the one is a method of study, the other is a method of communication.

Rhetoric, no less than logic, has subject-matter in every given case. Only its perverters teach it as merely an art of dealing with persons, of reaching an audience. No less than logic, it is a means of bringing out truth, of making people see what is true and fitting. But rhetoric contemplates having truth embraced. It is the application of proof to people. Its distinction from logic is here, in the typical mode of proof. The type in logic is the syllogism; the type in rhetoric Aristotle calls the enthymeme.[4] By this he means concrete proof, proof applicable to human affairs, such argument as is actually available in current discussion. The enthymeme is not inferior to the syllogism; it is merely different. Actually, public address on current public questions cannot be carried on by syllogisms or by final inductions. That by which it can be carried on, the strongest proof possible to actual discussion, Aristotle calls enthymeme.

From this typical mode of rhetoric Aristotle gathers its fourfold function: first and foremost, to make truth prevail by presenting it effectively in the conditions of actual communication, to move; second, to advance inquiry by such methods as are open to men generally, to teach; third, to cultivate the habit of seeing both sides and of analyzing sophistries and fallacies, to debate; and finally to defend oneself and one’s cause. That truth does not always prevail shows the need of effective presentation. The first function, then, of rhetoric is to make truth prevail among men as they are. Truth cannot be learned by the mass of men through scientific investigation; for that demands special training. A second direction, then, of rhetoric is to make the results of investigation generally available, to teach truth in general human terms. Debate, Aristotle’s third item, which is one whole field of rhetoric, may indeed be mere logical fence, using terms and propositions as mere counters; but real skill in debate, the habit of seeing both sides and of analyzing sophistries and fallacies, tends to make truth emerge from current discussion. The fourth use of rhetoric, for self-defense, seems added merely for completeness and to rebut the common objection that rhetoric is abused. That, says Aristotle, is no argument against it.[5]

The definition implied and sketched in Chapter I and formulated in