Kinds of Propositions. Certain kinds of propositions should never be chosen for argumentation. Many are incapable of proof, so any speech upon them would result in the mere repetition of personal opinions. Such are: The pen is mightier than the sword; Business men should not read poetry; Every person should play golf; Ancient authors were greater than modern authors. Others are of no interest to contemporary audiences and for that reason should not be presented. In the Middle Ages scholars discussed such matters as how many angels could stand on the point of a needle, but today no one cares about such things.
Propositions of Fact. Propositions fall into the two classes already illustrated by the statements about missionaries in China and the killing of Simon Lee. The second—John Doe killed Simon Lee—is a proposition of fact. All argument about it would tend to prove either the affirmative or the negative. One argument would strive to prove the statement a fact. The other argument would try to prove its opposite the actual fact. Facts are accomplished results or finished events. Therefore propositions of fact refer to the past. They are the material of argument in all cases at law, before investigation committees, and in similar proceedings. Lincoln argued a proposition of fact when he took Douglas's statement, "Our fathers, when they framed the government under which we live, understood this question just as well, and even better, than we do now," and then proved by telling exactly how they voted upon every measure dealing with slavery exactly what the thirty-nine signers of the Constitution did believe about national control of the practice. Courts of law demand that pleadings "shall set forth with certainty and with truth the matters of fact or of law, the truth or falsity of which must be decided to decide the case."
Propositions of Policy. Notice that the other proposition—Missionaries should not be sent to China—is not concerned with a fact at all. It deals with something which should or should not be done. It deals with future conduct. It depends upon the value of the results to be secured. It looks to the future. It deals with some principle of action. It is a question of expediency or policy. It induces argument to show that one method is the best or not the best. Propositions of expediency or policy are those which confront all of us at every step in life. Which college shall a boy attend? What kind of work shall a woman enter? How large shall taxes be next year? Which candidate shall we elect? How shall we better the city government? How shall I invest my money? What kind of automobile shall I buy? What kind of will shall I make?
The answers to all such questions make propositions of expediency or policy upon which arguments are being composed and delivered every day.
In choosing propositions for argument avoid, 1, those which are obviously truth; 2, those in which some ambiguous word or term covers the truth; 3, those in which the truth or error is practically impossible of proof; 4, those involving more than one main issue; 5, those which do not interest the audience.
Wording the Proposition. The proposition should be accurately worded. In law if the word burglary is used in the indictment, the defense, in order to quash the charge, need show merely that a door was unlocked. The phrasing should be as simple and concise as possible. The proposition should not cover too wide a field. Although these directions seem self-evident they should be kept in mind continually.
When the proposition is satisfactory to the maker of the argument he is ready to begin to build his proof. In actual speech-making few arguments can be made as convincing as a geometrical demonstration but a speaker can try to make his reasoning so sound, his development so cogent, his delivery so convincing, that at the end of his speech, he can exclaim triumphantly, "Quod erat demonstrandum."
Burden of Proof. Every argument presupposes the opposite side. Even when only one speaker appears his remarks always indicate the possibility of opposite views in the minds of some of the hearers. The affirmative and negative are always present. It is frequently asserted that the burden of proof is on the negative. This is no more correct than the opposite statement would be. The place of the burden of proof depends entirely upon the wording of the proposition and the statement it makes. In general the burden of proof is upon the side which proposes any change of existing conditions, the side which supports innovations, which would introduce new methods. With the passage of time the burden of proof may shift from one side to the other. There was a time when the burden of proof was upon the advocates of woman suffrage; today it is undoubtedly upon the opponents. At one period the opponents of the study of Latin and Greek had the burden of proof, now the supporters of such study have it. Other topics upon which the burden of proof has shifted are popular election of Senators, prohibition, League of Nations, self-determination of small nations, the study of vocations, civics, and current topics in schools, an all-year school term, higher salaries for teachers, the benefits of labor unions, Americanization of the foreign born.
Evidence. One of the best ways of proving a statement is by giving evidence of its truth. Evidence is made up of facts which support any proposition. In court a witness when giving testimony (evidence) is not allowed to give opinions or beliefs—he is continually warned to offer only what he knows of the fact. It is upon the facts marshaled before it that the jury is charged to render its verdict.
Direct Evidence. Evidence may be of two kinds—direct and indirect. This second, especially in legal matters, is termed circumstantial evidence. Direct evidence consists of facts that apply directly to the proposition under consideration. If a man sees a street car passenger take a wallet from another man's pocket and has him arrested at once and the wallet is found in his pocket, that constitutes direct evidence. Outside criminal cases the same kind of assured testimony can be cited as direct evidence.