Rhetoric   

relations of private individuals, these authors say nothing about
political oratory, but try, one and all, to write treatises on the way
to plead in court. The reason for this is that in political oratory
there is less inducement to talk about nonessentials. Political
oratory is less given to unscrupulous practices than forensic, because
it treats of wider issues. In a political debate the man who is
forming a judgement is making a decision about his own vital
interests. There is no need, therefore, to prove anything except that
the facts are what the supporter of a measure maintains they are. In
forensic oratory this is not enough; to conciliate the listener is
what pays here. It is other people's affairs that are to be decided,
so that the judges, intent on their own satisfaction and listening
with partiality, surrender themselves to the disputants instead of
judging between them. Hence in many places, as we have said already,
irrelevant speaking is forbidden in the law-courts: in the public
assembly those who have to form a judgement are themselves well able
to guard against that.
It is clear, then, that rhetorical study, in its strict sense, is
concerned with the modes of persuasion. Persuasion is clearly a sort
of demonstration, since we are most fully persuaded when we consider a
thing to have been demonstrated. The orator's demonstration is an
enthymeme, and this is, in general, the most effective of the modes of
persuasion. The enthymeme is a sort of syllogism, and the
consideration of syllogisms of all kinds, without distinction, is the
business of dialectic, either of dialectic as a whole or of one of its
branches. It follows plainly, therefore, that he who is best able to
see how and from what elements a syllogism is produced will also be
best skilled in the enthymeme, when he has further learnt what its
subject-matter is and in what respects it differs from the syllogism
of strict logic. The true and the approximately true are apprehended
by the same faculty; it may also be noted that men have a sufficient
natural instinct for what is true, and usually do arrive at the truth.
Hence the man who makes a good guess at truth is likely to make a good
guess at probabilities.
It has now been shown that the ordinary writers on rhetoric treat of
non-essentials; it has also been shown why they have inclined more
towards the forensic branch of oratory.
Rhetoric is useful (1) because things that are true and things that
are just have a natural tendency to prevail over their opposites, so
that if the decisions of judges are not what they ought to be, the
defeat must be due to the speakers themselves, and they must be blamed
accordingly. Moreover, (2) before some audiences not even the
possession of the exactest knowledge will make it easy for what we say
to produce conviction. For argument based on knowledge implies
instruction, and there are people whom one cannot instruct. Here,
then, we must use, as our modes of persuasion and argument, notions
possessed by everybody, as we observed in the Topics when dealing with
the way to handle a popular audience. Further, (3) we must be able to
employ persuasion, just as strict reasoning can be employed, on
opposite sides of a question, not in order that we may in practice
employ it in both ways (for we must not make people believe what is
wrong), but in order that we may see clearly what the facts are, and
that, if another man argues unfairly, we on our part may be able to
confute him. No other of the arts draws opposite conclusions:
dialectic and rhetoric alone do this. Both these arts draw opposite
conclusions impartially. Nevertheless, the underlying facts do not
lend themselves equally well to the contrary views. No; things that
are true and things that are better are, by their nature, practically
always easier to prove and easier to believe in. Again, (4) it is
absurd to hold that a man ought to be ashamed of being unable to
defend himself with his limbs, but not of being unable to defend
himself with speech and reason, when the use of rational speech is
more distinctive of a human being than the use of his limbs. And if it
be objected that one who uses such power of speech unjustly might do