Arguments of policy, on the other hand, which argue what ought to be done, make their appeal in the main to the moral, practical, Or aesthetic interests of the audience.  These interests have their ultimate roots in the deep-seated mass of inherited temperamental motives and forces which may be summed up here in the conveniently vague term “feeling.”  These motives and forces, it will be noticed, lie outside the field of reason, and are in the main recalcitrant to it.  When you argue that it is “right” that rich men should endow the schools and colleges of this country, you would find it impossible to explain in detail just what you mean by “right”; your belief rises from feelings, partly inherited, partly drawn in with the air of the country, which make you positive of your assertion even when you can least give reasons for it.  So our practical interests turn in the end on what we want and do not want, and are therefore molded by our temperament and tastes, which are obviously matters of feeling.  Our aesthetic interests, which include our preferences in all the fields of art and literature and things beautiful or ugly in daily life, even more obviously go back to feeling.  Now in practical life our will to do anything is latent until some part of this great body of feeling is stirred; therefore arguments of policy, which aim to show that something ought to be done, cannot neglect feeling.  You may convince me never so thoroughly that I ought to vote the Republican or the Democratic ticket, yet I shall sit still on election day if you do not touch my feelings of moral right or practical expediency.  The moving cause of action is feeling, though the feeling is often modified, or even transformed, by reasoning.  We shall come back to the nature of feeling in Chapter V, when we get to the subject of persuasion.

An important practical difference between arguments of fact and arguments of policy lies in the different form and degree of certitude to which they lead.  At the end of arguments of fact it is possible to say, if enough evidence can be had, “This is undeniably true.”  In these arguments we can use the word “proof” in its strict sense.  In arguments of policy on the other hand, where the question is worth arguing, we know in many cases that in the end there will be men who are as wise and as upright as ourselves who will continue to disagree.  In such cases it is obvious that we can use the word “proof” only loosely; and we speak of right or of expediency rather than of truth.  This distinction is worth bearing in mind, for it leads to soberness and a seemly modesty in controversy.  It is only in barber-shop politics and sophomore debating clubs that a decision of a question of policy takes its place among the eternal verities.

With these distinctions made, let us now consider a few of the chief varieties of these two classes of arguments, dealing only with those which every one of us comes to know in the practical affairs of life.  It will be obvious that the divisions between these are not fixed, and that they are far from exhausting the full number of varieties.