Testimony and Authority
All of the sources we have analyzed thus far are “internal” in the sense that they involve our own interpretation of experience. But there are two “external” sources, which utilize the interpretation of others. These are testimony and authority. The difference is that whereas the internal source, such as genus or cause, is a direct perception by us of an aspect of phenomena, the external source is a report of such perception on the part of someone else. If a police officer declares in court that he saw you drive through a red light at the intersection of 16th and Walnut, the court accepts his statement as testimony. After this is done, the statement goes into a syllogistic argument as a true proposition, constituting one of the premises. The point we must emphasize is that the proposition, as used in the argument, does not rest upon direct interpretation of genus, or cause, or similitude, but upon the credit of someone who is testifying. In the same way, a man who is charged with a crime gets someone to testify that he was otherwise occupied at the time the crime was committed (this is the true meaning of the charged person’s alibi, which is the Latin word for “elsewhere”). By this means, statements by people presumed to be in a position to know are brought into an argument and take the place of direct of logical interpretation of evidence.
Let us bear in mind that such arguments are external in the sense of being imported from the outside. Instead of affirming a fact of relationship themselves, they affirm that someone else affirms it. Thus the argument would not say that Tony Moreno was seventeen miles away from the scene at the time of a gangland slaying on Chicago’s south side. It says rather that his friend Joe Mangione testifies that Moreno was at his place, which is seventeen miles away from the scene, at the time of the slaying. How good this testimony is must be judged with reference to a number of things. The point of interest to us is that, in estimating its rhetorical force, we regard it not as a fact but as testimony.
Closely related to testimony is authority. Arguments from authority bring in a great name or some other exalted source whose word on the subject in question is regarded as final. Such arguments reflect a supposition that it would be presumptuous to go beyond the authority. The foreign missionary work carried on by many Christian churches rests upon the conclusion of an argument drawn from authority. According to the book of Matthew, Christ said to his disciples (28:19): “Go ye therefore and teach all nations.” The argument then proceeds; if Christ commanded his disciples to spread the gospel to all the world, this is what his followers must do. The Biblical text is thus used to supply a middle term, the authority of Christ, which functions in a syllogistic argument.
All of us have encountered, and perhaps some of us have used, arguments based on the authority of the Bible. If St. Paul said that the greatest of gifts is charity, we must accept this as so. Solomon declared that where there is no vision, the people perish, and we use this as a premise in argument. Arguments from authority are sometimes employed in the political arena. When Washington’s statement that we should avoid entangling alliances with foreign countries is cited in debate over foreign policy, it is the authority of Washington as father and first president of our nation which furnishes the rhetorical force. Sometimes even the subject matter of science is expressed in the form of arguments from authority, since it is obviously impossible to re-investigate every one of the established laws of science every time we wish to make a predication in this field. What we do, therefore, is accept a law on the authority of some competent scientist. When, for example, H. H. Newman, Professor of Zoology at the University of Chicago, declares: “Evolution has been tried and tested in every conceivable way for considerably over half a century. Vast numbers of biological facts have been examined in the light of this principle and without a single exception they have been found entirely compatible with it,” the average layman is disposed to regard this as true. Again we note that it is the authority of the source rather than any direct investigation of the content which gives propositions of this sort a standing in argument.
We repeat that it is the nature of arguments based on testimony and authority to have no intrinsic force; whatever persuasive power they carry is derived from the credit of the testifier of the weight of the authority. People who have been taught to venerate the Bible will be moved by a Biblical proposition; a proposition from the Koran would have little if any power to move them, though it would carry weight with a Moslem. In using such arguments it is accordingly essential to keep in mind the credit of the source of testimony and the status of the authority. Testimony is usually well regarded if the one offering it is in a position to know the facts and if he is disinterested with reference to the outcome of the argument.
In studying any extended piece of argumentation for its effect, you will find it invaluable to identify the rhetorical sources being employed. In no other way can you determine how much content an argument really has and how much weight it is probably going to carry with a specific audience.