A fallacy is an error in reasoning. The preceding part of this chapter has already suggested tests that will expose many such faults, but there are a few errors which, because of their frequency or their inadaptability to other classification, demand separate treatment. This book follows the plan of most other texts on argumentation, and treats these errors under a separate head marked fallacies. To detect a fallacy in another's argument is to weaken, if not to destroy, his case; to avoid making a fallacy in one's own argument means escape from humiliation and defeat. Hence, a knowledge of fallacies is one of the most essential parts of a debater's equipment.
The classification given here does not pretend to be exhaustive; it does, however, consider the most common and insidious breaches of reasoning that are likely to occur, and the following pages should be studied with great care.
I. BEGGING THE QUESTION. (PETITIO PRINCIPII.)
1. MERE ASSUMPTION. Begging the question means assuming the truth of that which needs proof. This fallacy is found in its simplest form in epithets and appellations. The lawyer who speaks of "the criminal on trial for his life," begs the question in that he assumes the prisoner to be a criminal before the court has rendered a verdict. Those writers who have recently discussed "the brutal game of football" without having first adduced a particle of proof to show that the game is brutal, fall into the same error. An unpardonable instance of question-begging lies in the following introduction, once given by a debater who was attacking the proposition, "Resolved, That the federal government should own and operate the railroads in the United States":—
"We of the negative will show that the efficient and highly beneficial system of private ownership should be maintained, and that the impracticable system of government ownership can never succeed in the United States or in any similarly governed country."
Private ownership and government ownership may possess these qualities attributed to them, but the debater has no right to make such an assumption; he must prove that they have these qualities.
2. ASSUMPTION USED AS PROOF. Such barefaced assumptions as the preceding usually do little damage except to the one who makes them. They are not likely to lead astray an audience of average intelligence; on the other hand, they do stamp the arguer as prejudiced and illogical. But when assumptions are used as proof, hidden in the midst of quantities of other material, they may produce an unwarranted effect upon one who is not a clear thinker, or who is off his guard. If, without showing that football is brutal, one calls it an extremely brutal game, and then urges its abolishment on the ground of its brutality, he has used an assumption as proof, and has, therefore, begged the question. The debater who stated, without proving, that vast numbers of unskilled laborers were needed in the United States, and then urged this as a reason why no educational test should be applied to immigrants coming to this country, furnished an example of the same fallacy.
3. UNWARRANTED ASSUMPTION OF THE TRUTH OF A SUPPRESSED PREMISE. The student is already familiar with the enthymeme. The enthymeme constitutes a valid form of reasoning only when the suppressed premise is recognized as true. Therefore, whenever an arguer makes use of the enthymeme without attempting to establish a suppressed premise whose truth is not admitted, he has argued fallaciously. This is a third method of begging the question. To illustrate: In advocating the abolishment of football from the list of college athletic sports, one might reason, "Football should be abolished because it obviously exposes a player to possible injury." The suppressed premise in this case would be: All sports which expose a player to possible injury should be abolished. Failure to prove the truth of this unadmitted statement constitutes the fallacy.
4. ASSUMPTION EQUIVALENT TO THE PROPOSITION TO BE PROVED. It is not surprising that a man carried away with excitement or prejudice should make assumptions that he does not even try to substantiate, but that anyone should assume the truth of the very conclusion that he has set out to establish seems incredible. Such a form of begging the question, however, does frequently occur. Sometimes the fallacy is so hidden in a mass of illustration and rhetorical embellishment that at first it is not apparent; but stripped of its verbal finery, it stands out very plainly. The following passage written on the affirmative side of the proposition, "Resolved, That the college course should be shortened to three years," will serve as a particularly flagrant illustration:—
It is a well-known fact that in the world of to-day time is an essential factor in the race for success. No young man can afford to dawdle for four long years in acquiring a so-called "higher" education. Three-fourths of that time is, if anything, more than sufficient in which to attain all the graces and culture that the progressive man needs.