Of the factors which make for the persuasiveness of an argument I will speak here of three—­clearness of statement, appeal to the practical interests of the audience, and direct appeal to their feelings.

There can be no doubt that clearness of statement is a powerful element in making an argument persuasive, though the appeal that it makes to the feelings of the readers is slight and subtle.  In practice we mostly read arguments either to help make up our minds on a subject or to get aid in defending views for which we have no ready support.  In the latter case we do not need to be persuaded; but in the former there can be no question that an argument which clears up the subject, and makes it intelligible where before it was confusing, does have an effect on us over and above its aid to our thought.

56.  The Practical Interests of the Audience.  Of directly persuasive power, however, are the other two factors—­the appeal to the practical interests of readers, and the appeal to their emotions.  Of these the appeal to practical interests has no proper place in arguments on questions of fact, but a large and entirely proper share in most arguments of policy.  Henry Ward Beecher’s speech on the slavery issue in the Civil War, before the cotton operatives of Liverpool,[60] is a classic example of the direct appeal to the practical interests of an audience.  They were bitterly hostile to the North, because the supplies of cotton had been cut off by the blockade; and after he had got a hearing from them by appealing to the English sense of fair play, he drove home the doctrine that a slave population made few customers for the products of English mills.  Then he passed on to the moral side of the question.

Arguments on almost all public questions—­direct election of senators, direct primaries, commission form of government, tariff, currency, control of corporations, or, in local matters, the size of a school committee, the granting of franchises to street railroads or water companies, the laying out of streets, the rules governing parks—­are all questions of policy in which the greatest practical advantage to the greatest proportion of those who are interested is the controlling force in the decision.  At particular times and places moral questions may enter into some of these questions, but ordinarily we come to them to settle questions of practical advantage.

In arguments on all such questions, therefore, the direct appeal to the practical interests of the people you are addressing is the chief factor that makes for persuasiveness.  Will a change to a commission form of government make towards a reduction of taxes and towards giving greater and more equitably distributed returns for those that are levied?  Will the direct primary for state officers make it easier and surer for the average citizen of the state to elect to office the kind of men he wants to have in office?  Will a central bank of issue, or some institution like it, establish the business of the country on a basis less likely to be disturbed by panics?  Will a competing street-car line make for better and cheaper transportation in the city?  In all such questions the only grounds for decision are practical, and founded in the prosperity and the convenience of the people who have the decision.