However, once the reader grasps that, in this context, Rhetoric simply means persuasion, which is divided into a) fact-and-reason based persuasion, or dialectic; and b) emotion-based persuasion, or rhetoric, the basic framework becomes clear. While some men can be persuaded by information and logical demonstration, most are more readily moved by what amounts to emotional manipulation. But there are some who can only be manipulated:
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.
It is more correct, more practical, and more effective to apply a principle of utilizing the form of communication best understood by the listener. Just as one would not speak Chinese to an individual who only understands English, one should not rely upon rhetoric when speaking to a dialectic-speaker, or expect a rhetoric-speaker to be persuaded by dialectical arguments.
Aristotle himself believed it was vital for a man to be skilled in both arts, not so much for the purposes of persuasion, but rather, to avoid being deceived.
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.
The Rhetoric is every bit as useful and valid today as when it was first written more than 2,300 years ago. It is less a work of philosophy than a treasure chest of practical information for the individual who seeks to pursue the Good, the Beautiful, and the True.