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, but in the case of such persons instruction is impossible.
AristotleMost men appear to think that the art of despotic government is statesmanship, and what men affirm to be unjust and inexpedient in their own case they are not ashamed of practicing towards others; they demand just rule for themselves, but where other men are concerned they care nothing about it. Such behavior is irrational; unless the one party is, and the other is not, born to serve, in which case men have a right to command, not indeed all their fellows, but only those who are intended to be subjects; just as we ought not to hunt mankind, whether for food or sacrifice . .
Aristotle