The choice of subject is even more important for debating than for written argument.  In a written argument if you have a question which has two defensible sides, it does not make much difference whether one is easier to defend than the other:  in a debate such a difference might destroy the usefulness of the subject.  Though to some older minds the abolition of football is a debatable question, before an audience of undergraduates who had to vote on the merits of the question the subject would be useless, since the side which had to urge the abolition would here have an almost impossible task.  So in a debate on the “closed shop,” in most workingmen’s clubs the negative would be able to accomplish little, for the other side would be intrenched in the prejudices and prepossessions of the audience.  In political bodies unevenness of sides is of common occurrence, for a minority must always defend its doctrines, no matter how overwhelming the vote is certain to be.  In the formal debates of school and college, on the other hand, where the conditions must be more or less artificial, the first condition is to choose a question which will give the two sides an even chance.

A fair test of this evenness of sides is to see whether the public which is concerned with the question is evenly divided:  if about the same number of men who are acquainted with the subject and are recognized as fair-minded take opposite sides, the question is probably a good subject for debate.  Even this test, however, may be deceptive, since believing a policy to be sound and being able to show that it is so are very different matters.  The reasons for introducing the honor system into a certain school or college are probably easier to state and to support than the reasons against introducing it; yet the latter may be unquestionably weighty.

In general, arguments which rest on large and more or less abstract principles are at a disadvantage as against arguments based on some immediate and pressing evil or on some obvious expediency.  Arguments for or against a protective tariff on general principles of political economy are harder to make interesting and, therefore, cogent to the average audience than are those based on direct practical gains or losses.  This difference in the ease with which the two sides of a question can be argued must be taken into account in the choice of a subject.

In the second place, the subject should be so phrased that it will inevitably produce a “head-on” collision between the two sides.  If such a proposition as “The present city government should be changed” were chosen for a debate, one side might argue it as a question of the party or of the men who happened to be in control at the time, and the other as a question of the form of government.  So on the question of self-government for a college or school, unless the type of self-government were carefully defined, the two sides might argue through the debate and not come in sight of each other.  What was said in Chapter II about framing the proposition for an argument applies with even more force to finding the proposition for a debate; for here if they do not meet on an irreconcilable difference, there is little use in their coming together.