As soon as the persuasive portion of an introduction has rendered the audience friendly, attentive, and open to conviction, the process of reasoning should begin. First of all, it is the duty of the arguer to see that the meaning of the proposition is perfectly clear both to himself and to all the people whom he wishes to reach. If the arguer does not thoroughly comprehend his subject, he is likely to produce only a jumble of facts and reasoning, or at best he may establish a totally different proposition from the one that confronts him; if the audience fails to understand just what is being proved, they remain uninfluenced. The amount of explanation required to show what the proposition means varies according to the intelligence of the people addressed and their familiarity with the subject.
DEFINITION.
To begin with, if there are any unfamiliar words in the proposition, any terms or expressions that are liable to be misunderstood or not comprehended instantly, they must be defined. At this point the arguer has to exercise considerable judgment both in determining what words to define and in choosing a definition that is accurate and clear. Synonyms are almost always untrustworthy or as incomprehensible as the original word, and other dictionary definitions are usually framed either in too technical language to be easily grasped or in too general language to apply inevitably to the case at hand.
DEFINITION BY AUTHORITY. As a rule, the very best definitions that can be used are quotations from the works of men distinguished for their knowledge in the special subject to which the word to be defined belongs. The eminent economist defines economic terms; the statesman, political terms; the jurist, legal terms; the scientist, scientific terms; the theologian, the meaning of religious phraseology. To present these definitions accurately, and to be sure of the author's meaning, one should take the quotations directly from the author's work itself. If, however, this source is not at hand, or if time for research is lacking, one may often find in legal and economic dictionaries and in encyclopaedias the very quotations that he wishes to use in defining a term. It is always well, in quoting a definition, to tell who the authority is, and in what book, in what volume, and on what page the passage occurs.
Another convenient way of using definition by authority is not to quote the entire definition but to summarize it. Frequently an authoritative definition is so exhaustive that it covers several pages or even chapters of a book. In such a case the arguer may well condense the definition into his own words, not omitting, however, to name the sources used. The following example is an excellent illustration of this method:—
The bearing of the Monroe Doctrine on all these contentions and counter contentions is not at once evident to the casual observer…. Of course with changing times its meaning has changed also, for no one attempts to declare it to be as immutable as the law of the Medes and Persians. It is applied in various ways to meet varying conditions. Nevertheless, I may say I believe, after a perusal of the more important works on the subject, that during the forescore years of its existence two principles have steadily underlain it: (1) that Europe shall acquire no more territory for permanent occupation upon this continent; (2) that Europe shall affect the destinies of, that is exert influence over, no American state.[Footnote: A. B. Hart, Foundations of American Foreign Policy, chap. VII; J. W. Foster, A Century of American Diplomacy, chap. XII; J. A. Kasson, The Evolution of the Constitution of the United States of America, pages 221 ff. [Footnote: Nutter, Hersey & Greenough, Specimens of Prose Composition, p. 218. ] ]
DEFINITION BY ILLUSTRATION. Since the purpose of each step in the reasoning portion of the introduction is to convey information accurately, quickly, and, above all else, clearly, a particularly good method for defining terms is by illustration. In using this method, one holds up to view a concrete example of the special significance of the word that is being explained. He shows how the law, or custom, or principle, or whatever is being expounded works in actual practice. For example, if he is advocating the superiority of the large college over the small college, he should define each term by giving specific examples of large colleges and of small colleges. The advantage of this method lies in its simplicity and clearness, qualities which enable the audience to understand the discussion without much conscious effort on their part. Investigation reveals that the definitions of great writers and speakers are replete with illustration. Whenever the student of argumentation has something to define that is particularly intricate or hard to understand, he should illustrate it. If he fails to find already prepared an illustrative definition that exactly fits his needs, he will often do well to learn just what the term means, and then make his own illustration.
Consider how this method has been used. The Hon. Charles Emory Smith defines reciprocity as follows:—
Its principle, rightly understood, is axiomatic. Brazil grows coffee and makes no machinery. We make machinery and grow no coffee. She needs the fabrics of our forges and factories, and we need the fruit of her tropical soil. We agree to concessions for her coffee and she agrees to concessions for our machinery. That is reciprocity.
The following is a definition of free silver by The Hon. Edward O.
Leech, former Director of the Mint:—