Aristotle, Rhetoric
J. H. Freese, Ed.

That is why, as I have said before, in many places the law prohibits speaking outside the subject in the law courts, whereas in the assembly the judges themselves take adequate precautions against this.

[11] It is obvious, therefore, that a system arranged according to the rules of art is only concerned with proofs; that proof is a sort of demonstration,¹ since we are most strongly convinced when we suppose anything to have been demonstrated; that rhetorical demonstration is an enthymeme, which, generally speaking, is the strongest of rhetorical proofs and lastly, that the enthymeme is a kind of syllogism. Now, as it is the function of Dialectic as a whole, or of one of its parts,² to consider every kind of syllogism in a similar manner, it is clear that he who is most capable of examining the matter and forms of a syllogism will be in the highest degree a master of rhetorical argument, if to this he adds a knowledge of the subjects with which enthymemes deal and the differences between them and logical syllogisms. For, in fact, the true and that which resembles it come under the purview of the same faculty, and at the same time men have a sufficient natural capacity for the truth and indeed in most cases attain to it; wherefore one who divines well in regard to the truth will also be able to divine well in regard to probabilities.³

It is clear, then, that all other rhetoricians bring under the rules of art what is outside the subject,
and⁴ have rather inclined to the forensic branch of oratory. [12] Nevertheless, Rhetoric is useful, because the true and the just are naturally superior to their opposites, so that, if decisions are improperly made, they must owe their defeat to their own advocates; which is reprehensible. Further, in dealing with certain persons, even if we possessed the most accurate scientific knowledge, we should not find it easy to persuade them by the employment of such knowledge. For scientific discourse is concerned with instruction,⁵ but in the case of such persons instruction is impossible; our proofs and arguments must rest on generally accepted principles, as we said in the Topics,⁶ when speaking of converse with the multitude. Further, the orator should be able to prove opposites, as in logical arguments; not that we should do both （for one ought not to persuade people to do what is wrong）, but that the real state of the case may not escape us, and that we ourselves may be able to counteract false arguments, if another makes an unfair use of them. Rhetoric and Dialectic alone of all the arts prove opposites; for both are equally concerned with them. However, it is not the same with the subject matter, but, generally speaking, that which is true and better is naturally always easier to prove and more likely to persuade. Besides, it would be absurd if it were considered disgraceful not to be able to defend oneself with the help of the body,