If this approach seems to leave some questions unanswered, let us go back to a more fundamental position and think for a moment about the types of assertions we make. We soon become aware that all our assertions reflect our interpretation of the phenomena of existence, and that this interpretation is expressed through certain ultimate conceptions. The most basic of these are, in the language of philosophy, being, cause, and relationship; but we need to translate these terms into language more suited to our purpose. Accordingly, in our everyday assertions we say that a thing exists as a member of a class, or that it is the known cause of a certain effect or the known effect of a certain cause, or that it has points of resemblance with some other thing. “All Democrats are friends of the people” is an assertion of the first type; “War is a cause of inflation” is one of the second, and “Life is like a voyage” is one of the third. These statements about the nature of things enter into arguments (or, strictly speaking, into propositions) and it is the forcefulness with which they impress us that supplies the rhetorical effectiveness of any argument.
Let us restate this from another point of view. It is never enough to have merely a device of argument. A device is only a form, and though forms may delight the intellect, they are seldom if ever sufficient to move that refractory object which is our total being. The total being is moved, if at all, but the content of the argument, and it is content alone with which we are now dealing.
The first writer to give due recognition to content in addition to form was Aristotle, the founder of logic and the author of a treatise on rhetoric. He conceived the content of argument as a group of sources or “topics.” It sheds some light upon this terminology to know that “topics” comes from the Greek word topoi, which signifies “regions” or “places” (cf. topography). The connection becomes clearer when we understand that the “topics” are comprised of those regions of experience from which the propositions of argument can be drawn. We have emphasized the fact that our propositions in argument consist of assertions which reflect our reading of experience. They must say things that we know to be true according to these necessary ways of knowing our world. In proportion as we make the propositions seem truthful, we give an argument power to impel the hearer.
No useful end would be served by going over Aristotle’s list of topics minutely, for there is doubt as to whether he arranged them systematically. Moreover, the topics are not a matter which should be settled by appeal to authority, since we ourselves are qualified judges of the kinds of assertions that move people to acceptance. But taking up the list selectively, we find that the following topics or kinds of statements are the ones most widely understood and most effective in persuading.