Part 9 (1/2)
Either one by itself may be untrustworthy. The unreliability of evidence given by eyewitnesses is shown by the conflicting stories they frequently tell concerning the same incident even when they are honestly attempting to relate the facts as they occurred. Also, it is always possible that the inferences drawn from a combination of circ.u.mstances may be entirely wrong. When, however, both kinds of evidence are available, each confirming the other and leading up to the same conclusion, then the possibility of error is reduced to a minimum.
The opportunity of the college student for obtaining evidence in his argumentative work is limited. A lawyer before entering upon an important case often spends weeks and months in investigation; scientists sometimes devote a whole lifetime in trying to establish a single hypothesis. But the college student in preparing an argument must obtain his evidence in a few days. There are several sources at his disposal. The first available source is his fund of general knowledge and experience. If a man can establish a statement by saying that he personally knows it to be true, he has valuable proof. Then the people with whom the student comes in contact const.i.tute another source of evidence. Anyone who can give information on a subject that is being investigated is a valuable witness. Especially in discussions on questions which pertain to college life, the opinions and experiences of college men and of prominent educators are unsurpa.s.sed as evidence. But the greatest source of evidence for the student of argumentation is the library. Here he may consult the best thought of all time in every branch of activity. He may review the opinions of statesmen, economists, educators, and scientists, and introduce as evidence their experiences and the results of their investigations.
Here he may familiarize himself with the current events of the world, and draw his own conclusions as to their significance. In fact, a well equipped library treats of all subjects, however broad or narrow they may be, and furnishes evidence for all sorts of debatable questions.
As not all evidence is equally valuable, a large part of the work of argumentation consists in applying tests to the evidence at hand for the sake of determining what facts are irrefutable, what are doubtful, and what are worthless. Moreover, one engaged in argumentation must test not only his own evidence but also that of the other side. No better method of refuting an opponent's argument exists than to show that the facts on which it rests are untrustworthy. Tests of evidence may be divided into two cla.s.ses: tests of the source from which it comes, and tests of the quality of the evidence itself.
A. TESTS OF THE SOURCE OF EVIDENCE.
Since in courts of law, in college debate, and in all kinds of argumentation, facts are established by the testimony of witnesses, the sources of evidence are the witnesses who give it. The debater and the argumentative writer have not the opportunity, as has the lawyer, of producing the witnesses and permitting them to tell their own stories to the audience. He must himself relate the evidence; and, in order that it may be believed, he must tell whence it comes. The sources of evidence may be common rumor, newspapers, magazines, official doc.u.ments, private citizens, or public officials. The extent to which these witnesses are accepted as trustworthy by the people before whom they are quoted determines in a large measure whether or not the evidence will be believed. Tests for determining the trustworthiness of witnesses will next be given.
The first test of the source of evidence should be:--
(1) _Is the witness competent to give a trustworthy account of the matter under consideration?_
To answer this question, first determine whether the facts to be established are such that any ordinary person can speak concerning them with reasonable accuracy, or whether they can be understood only by persons who have received special training. A landsman could well testify that a naval battle had occurred, but only a man with nautical training could accurately describe the maneuvers of the s.h.i.+ps and tell just how the engagement progressed. A coal heaver's description of a surgical operation would establish nothing, except perhaps the ident.i.ty of the people and a few other general matters; only a person with a medical education could accurately describe the procedure. The testimony of any one but a naturalist would not even tend to prove the existence of an hitherto unknown species of animal life. A witness without technical knowledge cannot give reliable evidence on matters of a technical nature.
Then, if it is found that the witness does possess the necessary technical training, or that no previous training is necessary, still further test his ability to give reliable evidence by asking whether he has had ample opportunity for investigating the facts to the existence of which he testifies. For even a skilled player sitting in the first base bleachers at a baseball game to criticise an umpire's decisions on b.a.l.l.s and strikes is absurd; the opinion of a transient visitor to Panama on the methods used in digging the ca.n.a.l is not valuable; a traveler who has spent a single month in j.a.pan cannot draw reliable conclusions on the merits and defects of its political structure. In not one of these cases has the opportunity for investigation been sufficient to render the witness able to give reliable evidence.
A current magazine in discussing the weakness of testimony that comes from incompetent witnesses says:--
Generalizations about the tastes and interests of the age are so easy that all except the most wary fall into them, and the world is full of off-hand opinions touching the condition of society and the state of the world, which are far more conspicuous for courage than for discretion. There are very few men or women in any particular period who know it intimately enough, and with sufficient insight and sympathy, to pa.s.s judgment upon it. One hears almost every day sweeping judgments about Americans, English, French, Germans, Chinese, and j.a.panese which are entirely valueless, unless they are based on a very broad and intimate knowledge of these various peoples, a knowledge which, in the nature of things, few people possess. The charming American girl who declared that, since gloves are cheaper in Paris, American civilization is a failure, may stand for a type of interesting and piquant oracles, to be heard with attention, but under no circ.u.mstances to be followed. Americans are so familiar with the European traveler who arrives and makes up his opinion over night in regard to men, morals, and manners in the Western world and have so often been the victim of this self-confident critic, that they ought not to repeat the same blunder in dealing with other peoples.
[Footnote: The Outlook, July 20, 1907.]
In the court room, where witnesses are present and can be carefully examined by the lawyers on both sides, it is customary to apply both mental and physical tests. The witness who testifies to knowledge of some event that occurred a long time before is given a memory test; the senses, also, through which occurrences are perceived are frequently examined. But as writers and debaters in general seldom have the opportunity to apply tests of this sort to their sources of information, and as these tests are seldom important outside of the law courts, they are not taken up in detail in this book.
The second test of the source of evidence should be:--
(2) _Is the witness willing to give an accurate account of the matter?_
One important influence that may cause a witness to give false evidence is _self-interest_. Not only individuals, but social and industrial organizations, political parties, communities, and states are frequently swayed by this emotion to the extent of deliberately perverting the truth. The evidence found in newspapers and other publications is often false, or at least misleading, because it has been tampered with by those who put their selfish interests before all else. The owner of an industry protected by a high tariff would scarcely be considered a reliable witness in matters affecting tariff reform. The opinion of a railroad magnate on the subject of a compulsory two-cent rate law would not be considered as unbiased. No disinterested seeker after truth would accept the political conclusions of a newspaper owned by a politician or recognized as the organ of a certain party. In all such cases, self-interest may prompt the witness to make statements not in strict accordance with the truth. Perjury in the court room is not uncommon; falsehood elsewhere must be guarded against. The arguer should always carefully scrutinize the testimony of a witness that has any special interest in the matter for which evidence is being sought. Though the self-interest is strong, the witness may be willing to state the matter accurately; but, as long as human nature remains as it is, this willingness should not be taken for granted.
The third test of the source of evidence should be:--
(3) _Is the witness prejudiced?_
Another emotion that frequently keeps a witness from telling the exact truth is _prejudice_. Every one is familiar with instances of how this pa.s.sion warps men's morals and corrupts their judgment. If a man is prejudiced for or against a person or a system, he cannot be accepted as a trustworthy witness in matters where his prejudice comes into play. Should an economist known to favor socialism write a treatise advocating munic.i.p.al owners.h.i.+p of public utilities, his evidence and his reasoning would not be convincing; it would be taken for granted that he looked at the subject through socialistic spectacles. A person who sets out with the expectation and intention of finding flaws in anything usually succeeds. Though he is willing to tell the exact truth, yet because of his prejudice he is sure to see only that which will coincide with his preconceived opinions. For this reason, political speeches and intensely partisan books and papers are invariably unreliable sources of evidence even though they are not intentionally dishonest.
The fourth test of the source of evidence is:--
(4) _Does the witness have a good reputation for honesty and accuracy?_
The human conscience is so const.i.tuted that many people deviate from the truth for no apparent reason whatever. Some are given to exaggeration; some habitually pretend to know that of which they are entirely ignorant; others are so inaccurate that everything they say is open to grave suspicion. If a witness is known to have been repeatedly dishonest or inaccurate in the past, little reliance should be placed in his testimony. ”Yellow journalism,” which is largely the reflection of common rumor, affords constant examples of witnesses that give questionable evidence.
Ability and willingness to give exact evidence, an unprejudiced att.i.tude, and a good reputation for honesty and accuracy are the qualities that should characterize the sources of evidence. If a writer or speaker is securing testimony from friends or acquaintances, the application of these tests is not difficult. If, however, the sources are books and periodicals, his work is harder; but to be successful, he must not s.h.i.+rk it. When one procures evidence from books, he should investigate the character and standing of the author.
When one obtains it from signed articles in papers and magazines, he must consider both the author and the character of the publication. In the case of newspaper ”stories” and editorials, one should find out on what general policy and principles the paper is conducted. A cautious arguer will always avoid, as far as he can, the use of evidence that comes from a doubtful source. If one finds that an opponent has used the testimony of questionable witnesses, he can, by exposing the fact, easily refute the argument.
NECESSITY OF STATING SOURCES. It sometimes happens that an arguer fails to state the source of his evidence. This omission is usually fatal to success. No one is likely to put much confidence in statements that are introduced by such flimsy preambles as, ”A certain statesman has declared”; ”I have read somewhere”; ”An acquaintance told me.” Not only must evidence come from sources that seem good to the writer, but those sources must be satisfactory to the audience. In the last a.n.a.lysis the audience is the judge of what is credible and what is not. Moreover, if the evidence is of great importance, or is liable to be disputed, the arguer should show in a few words why the witness is especially reliable.
B. INTERNAL TESTS OF EVIDENCE