The same faculty, on a smaller scale, is needed by every one of us who is trying to make other people do anything.  The actual use of the faculty will vary greatly, however, with different kinds of arguments.  In certain kinds of scientific argument any attempt at persuasion as such would be an impertinence:  whether heat is a mode of motion, whether there are such infinitesimal bodies as the ions which physicists of to-day assume to explain certain new phenomena, whether matter consists of infinitesimal whirls of force—­in all such questions an argument appeals solely to the reason; and in such Bacon’s favorite apophthegm has full sway, Dry light is ever the best.  In Huxley’s arguments for the theory of evolution feeling had some share, for when the theory was first announced by Darwin some religious people thought that it cut at the foundations of their faith, and Huxley had to show that loyalty to truth is a feeling of equal sanctity to scientific men:  hence there is some tinge of feeling, though repressed, in his argument, and a definite consciousness of the feelings of his audience.

At the other extreme are the arguments where the appeal to feelings is everything, since it is clear that the audience is already of the speaker’s way of thinking.  Examples of such arguments are most apt to be found in speeches in political campaigns and in appeals for money to help forward charities of all kinds.  It is probable that most of the conversions in political matters are through reading; consequently the purpose of the speeches is to stir up excitement and feeling to such a heat that the maximum of the party voters will take the trouble to go out to the polls.  Arguments directed to this class, accordingly, are almost wholly appeals to feeling.  The famous debate between Lincoln and Douglas in 1858 was of this character; of the thousands of people who heard them in one or another of the seven debates most had taken sides already.  In such a case as this, however, where a change in general political opinion was impending, the reasoning of the debates had more force than in ordinary times, and probably helped many voters to a clearer view of a very distressing and harassing situation.  Between times, however, in politics, where there are no great moral or practical differences between parties, the purpose of speeches is almost wholly persuasive.  Success one way or another is a question of getting out the voters who more or less passively and as a matter of habit hold to the party.  Party speakers, accordingly, use every device to wake up their voters, and to make them believe that there is a real crisis at hand.  Every attempt is made to attach moral issues to the party platforms, and to show how the material prosperity of the voters will fail if the other party wins.

Roughly, therefore, we may say that persuasion tends to play a small part in arguments of facts, and a larger part in questions of policy.  This is a rough generalization only, for every one knows what eloquence and efforts at eloquence go into the arguments before juries in capital cases, and how dry and abstract are the arguments before the judges on points of law, or on questions of public policy in books of political economy.  But in the long run, the less feeling enters into decisions of questions of fact, the better.