a rhetorical exercise, or for the purpose of eliciting the truth by the juxta-position of conflicting views, compose an argument on opposite sides of a question. Examples of this species of composition are afforded by all writings in the form of a controversial dialogue, such as the dialogues of Plato and Cicero and the Minute Philosopher of Berkeley. A person who produces an argument, produces something which can be judged without reference to himself, and which is not necessarily either confirmed or enfeebled by his individual qualities or circumstances. A new demonstration of a mathematical problem would in no way depend on the character of its inventor. But the witness to a fact can only depose truly to that fact; he cannot, like the arguer, choose his ground hypothetically; and the credibility of his testimony depends solely on his own personal circumstances and moral character.

§ 2. Anonymous testimony to a matter of fact, is therefore wholly devoid of weight; unless, indeed, there be circumstances which render it probable that a trustworthy witness has adequate motives for concealment, or extraneous circumstances may support and accredit a statement, which, left to itself, would fall to the ground.

Thus an anonymous communication may put a man on his guard, or may induce him to make inquiries in a certain direction, when it appears probable from the contents of the communication, or from other circum

knew that it were purchased. There is a beautiful image in Bacon upon this subject: Testimony is like an arrow shot from a long bow-the force of it depends on the strength of the hand that draws it; argument is like an arrow from a cross-bow, which has great force though shot by a child.'"-BOSWELL'S Johnson, vol. viii. p. 281.

stances, that it may proceed from some quarter in which secrecy is rendered inevitable by a powerful interest. Such was the letter to Lord Monteagle concerning the Gunpowder Plot; such are threatening letters, or letters giving private information respecting the conduct of individuals, in a public or private capacity. Occasionally, it happens that important suggestions are conveyed in this manner; but, for the most part, information given anonymously turns out, on investigation, to be utterly worthless. An anonymous work, too, may sometimes exhibit internal evidence of truth; that is, there may be certain marks in the writing which give it an air of veracity, though the author may have deemed it prudent to withhold his name from the public. It is in this manner that anonymous statements of facts in newspapers are authenticated: the periodical appearance of the newspaper and the character which its management may have acquired for correctness of intelligence, serving as guarantees for the truth of its statements.* Statements in an anonymous publication may likewise acquire credibility from their remaining uncontradicted by persons who have an interest in contradicting them, and are acquainted with the facts of the case. It may be added that a work may be anonymous, from the loss of the author's name, though its original publication may not have been anonymous. For instance, the Acts of the Apostles, and many chronicles of the middle ages, are now anonymous, though there is no reason to suppose that the authors concealed their names from their contemporaries.

With these exceptions-which are rather apparent

* See this subject further pursued in Chapter IX.

than real-it is essential to testimony that we should know the witness as well as the fact, and be able to estimate his individual qualifications, as a testifier or relator. Whereas, in the case of an argument, its conclusiveness, considered without reference to the truth of its premises, and judged merely by logical rules, is wholly independent of its author.

This independence of an argument with respect to the character of its author, implies, however, both that its inferential force is thoroughly understood, and that the truth of its premises is conceded. Whenever this is not the case, the character of the person who advances the argument is a most material consideration; and it is to cases of this sort that our present inquiry relates—that is to say, to cases where an opinion is accepted out of confidence in the person who holds it, and without any full comprehension of its grounds.

§ 3. It may be added that for all purposes of philosophical observation, a knowledge of the proper science, and a peculiar training of the senses, are requisite, and therefore that a witness who possesses these qualifications is far more credible than one who is destitute of them. For example, a scientific naturalist who reports that he has seen an undescribed animal or vegetable in a remote country, is far less likely to be mistaken than a common traveller, ignorant of natural history. A skilled witness of this sort may be considered, in a certain sense, as a witness of authority, inasmuch as his previous study and habits of observation give a peculiar weight to his report of the phenomenon.

§ 4. The distinction between testimony, argument, and authority, may be briefly summed up thus:

In questions of testimony, I believe a matter of fact, because the witness believes it.

In questions of argument, I believe the conclusion to be true, because it is proved by reasons satisfactory to my understanding.

In questions of authority, I believe a matter of

opinion, because it is believed by a person whom

I consider a competent judge of the question.

§ 5. Now, on looking at the qualities which render any one a credible witness to a matter of fact, we may remark that they are of common occurrence. For testimony, nothing further is in general required than opportunity of observation, ordinary attention and intelligence, and veracity. Almost every person of sound mind, who has reached a certain age, is a credible witness as to matters which he has observed, and as to which he has no immediate interest in deception or concealment.* For purposes of scientific observation, indeed, (as has been remarked,) a certain skill and practice beyond that possessed by ordinary persons is requisite; but when this has been acquired, no extraordinary qualifications are needed.

The qualities which render a person a competent authority in matters of opinion are of rarer occurrence.

* For the administration of justice, it is important that there should be some recognised tests of the credibility of witnesses to facts in dispute before the court. In almost all systems of judicial procedure, an attempt has been made to lay down inflexible legal rules on this subject. Thus, in some cases, the concurrent testimony of two witnesses to the same fact has been rendered necessary; the evidence of persons standing in a near degree of affinity to one of the parties, or having a pecuniary interest in the cause, has been excluded. But experience has shown that, however useful maxims of this sort may be as guiding the discretion of the court in weighing the credibility of witnesses, the entire exclusion of evidence on such grounds obstructs the administration of justice.

Many of them are, separately, not frequent; and the combination of them in the same individual is necessarily more uncommon; a person whose testimony to a fact would be unimpeachable, might be utterly devoid of authority as a guide of opinion. Besides, a person who is a credible witness for one matter of fact, is equally credible for all others which may fall under his observation; whereas (as we shall see hereafter) no man is equally competent as a guide of opinion in all subjects, and, in general, the authority of each person is, as compared with the sum total of human affairs, confined within a narrow range.

§ 6. The first qualification is, that a person should have devoted much study and thought to the subjectmatter if it be merely speculative; and that if it be practical, he should also have had adequate experience respecting it.

Secondly, his mental powers must be equal to the task of comprehending the subject, and they must be of the sort fitted to it.

Thirdly, he ought to be exempt, as far as possible, from personal interest in the matter; or, if he be not exempt, his honesty and integrity ought to be such as to afford a reasonable security against the perversion of his opinions by views of his individual advantage.

§ 7. The three qualifications just stated may now be examined with somewhat more of detail.

I. If the subject be extensive-if it be one of the great departments into which human knowledge is divided a careful study of it, continued for several years, or even for a large part of a life, combined with frequent meditation, and, if possible, personal observation, is requisite in order to enable a man to understand it thoroughly and to treat it with a sound and compre