CHAPTER VIII.

ARGUMENTATION.

62. ARGUMENTATION is the most difficult kind of composition. It is, in fact, too difficult for the young and immature. To deal with it profitably, one should be familiar with the general principles of Logic, i. e., with the Syllogism, the relation of Cause and Effect, Analogy, the nature of Evidence, the processes of Induction and Deduction. At least all these branches are involved in the study of the general theory of argumentation, although in actual life each profession makes especial use of one branch, so that the individual member of the profession acquires technical facility in the use of the methods peculiar to it. Thus the lawyer, as lawyer, is trained in the (Court) rules of Evidence, see §70; his argumentation is chiefly in the line. of Analogy, or of deduction from Definitions, see §§ 72, 73. The mathematician uses almost exclusively the process of Deduction from Definitions and Axioms, see § 69. The scientist uses Induction and Deduction, see § 68.

In the present work nothing is attempted beyond indicating briefly the various classes of arguments, their respective values, and the uses to which they may be put. Enough is given to enable the young reader to follow a line of argumentation and estimate approximately its force and its weakness.

GENERAL FEATURES.

63. Argumentation is an attempt to prove or disprove a proposition. By proposition is meant an assertion which is or may be drawn up in the form: A. is B., e. g., "Every

man is the architect of his own fortune;" "Men are responsible for their opinions;" "N. owes M. $5000 on a promissory note;" "N. is guilty of the crime of having murdered M."

Each of the above propositions is an assertion to be established. The means by which it is established are called Arguments or Proofs. In legal proceedings the term proof is used to designate the testimony of witnesses, documents (such as wills or deeds), and other matters of fact; while the term argument is restricted to the inferences drawn from such data by the advocate (lawyer) on one side or the other. But in non-legal reasoning this distinction is not observed. Any fact, any form of words, used to establish a proposition, may be called indiscriminately a proof or an argument. The verb "to prove" is used without distinction. In formal logic (and mathematics) the proving of a proposition beyond the possibility of doubt is called a Demonstration.

For practical purposes we may classify arguments according to the principle of Certainty and Probability, or according to the principle of General and Particular. classes cross each other, see §§ 52, 67.

CERTAINTY AND PROBABILITY.

The

64. The first step in understanding argumentation is to learn the difference between an argument which establishes the proposition with certainty, and one which establishes it only to a varying degree of probability. The difference is that between science on the one hand, and the great body of historical, political, and legal reasoning on the other. The term Certainty is used here in two senses:

a. Absolute certainty, the opposite of which is inconceivable, e. g., in mathematics, the demonstration that the angles at the base of an isosceles triangle are equal.

b. In physical and biological science, that practical certainty which is obtained through repeated induction and

deduction and tested by repeated experiments until it becomes an unquestioned rule.

The difference between scientific argumentation and literary (or legal) is illustrated by the following quotations:

If beautiful objects had been created solely for man's gratification, it ought to be shown that before man appeared there was less beauty on the face of the earth than since he came on the stage. Were the beautiful volute and cone shells of the Eocene epoch, and the gracefully sculptured ammonites of the Secondary period, created that man might ages afterwards admire them in his cabinet? Few objects are more beautiful than the minute siliceous cases of the diatomacea; were these created that they might be examined and admired under the higher powers of the microscope? The beauty in this latter case, and in many others, is apparently wholly due to symmetry of growth.-DARWIN: Origin of Species, ch. vi.

Darwin's argument that beauty of form existed prior to, and therefore independent of, the creation of man is apparently unanswerable. In the rest of the paragraph he discusses in like manner beauty of color.

One of the proofs that radiant heat and radiant light are the same thing, or only variations of the same thing, is thus given:

The radiant heat from the sun goes along with the light from the sun, and when you shut one off,-put a screen so as to intercept the one, the other is intercepted at the same time. In the case of a solar eclipse, you have the sun's heat as long as you see the smallest portion of the sun's disc. The instant the last portion of the disc is obscured, the heat disappears with the light. That shows that the heat and light take not only the same course, but also the same time to come to us. If the one lagged ever so little behind the other,—if the heat disappeared sooner than the light, or the light sooner than the heat,—it would show that though they both moved in straight lines, the one moved faster than the other; but the result of observation is that we find, so far as our most delicate measurements show, that heat and light are simultaneously intercepted.-TAIT: Recent Advances, ch. viii.

The above may be contrasted with Macaulay's attempt to prove that Sir Philip Francis was the author of the "Junius" letters:

Was he the author of the "Letters of Junius"? Our own firm belief is that he was. The evidence is, we think, such as would support a verdict in a civil, nay, in a criminal proceeding. The handwriting of Junius is the very peculiar handwriting of Francis, slightly disguised. As to the position, pursuits, and connections of Junius, the following are the most important facts which can be considered as clearly proved: first, that he was acquainted with the technical forms of the Secretary of State's office; secondly, that he was intimately acquainted with the business of the War-office; thirdly, that he, during the year 1770, attended debates in the House of Lords, and took notes of speeches, particularly of the speeches of Lord Chatham; fourthly, that he bitterly resented the appointment of Mr. Chamier to the place of Deputy Secretary at War; fifthly, that he was bound by some strong tie to the first Lord Holland. Now, Francis passed some years in the Secretary of State's office. He was subsequently chief clerk of the War-office. He repeatedly mentioned that he had himself, in 1770, heard speeches of Lord Chatham; and some of these speeches were actually printed from his notes. He resigned his clerkship at the War-office from resentment at the appointment of Mr. Chamier. It was by Lord Holland that he was first introduced into the public service. Now, here are five marks, all of which ought to be found in Junius. found in Francis. We do not believe that more than two of them can be found in any other person whatever. If this argument does not settle the question, there is an end of all reasoning on circumstantial evidence.-MACAULAY: Warren Hastings.

They are all five

So far from settling the question, Macaulay left it where he found it; perhaps he rather obscured than illuminated it, see $75. Certainly the drift of present opinion is against identifying Francis with Junius.*

65. Without going into the remote field of history, we may contrast (practical) certainty with mere probability (of a high order) by a slight every-day test. If we observe plants, e. g., potato-vines or tomatoes, growing in straight lines that cross each other at regular intervals, we infer that they have been planted there by human agency, and we could not seriously entertain any other explanation. But when we observe the flag flying over the Capitol at

* See London Athenæum, Aug. 11, 25, Sept. 8, 1888; Dec. 14, 1889; June 28, Aug. 9, 1890; Jan. 24, 1891; March 17, 24, 1894.

Washington and infer that Congress is in session, our inference is not certain, but only highly probable. The connection between the sitting of Congress and the flying of the flag is merely a variable human custom. It is always possible that the flag-keeper may have run up the flag through mistake, or may have forgotten to lower it after adjournment. Or perhaps the flag is flying in honor of some national holiday.

Huxley, one of the acutest of reasoners, has expressed himself in a paragraph which has been much quoted and sometimes misunderstood:

So, the vast results obtained by Science are won by no mystical faculties, by no mental processes other than those which are practised by every one of us in the humblest and meanest affairs of life. A detective policeman discovers a burglar from the marks made by his shoe, by a mental process identical with that by which Cuvier restored the extinct animals of Montmartre from fragments of their bones. Nor does that process of induction and deduction by which a lady, finding a stain of a peculiar kind upon her dress, concludes that somebody has upset the inkstand thereon, differ in any way, in kind, from that by which Adams and Leverrier discovered a new planet.-HUXLEY (v.), p. 78. This is truth, but not the whole truth. Huxley's chief motive was to strip induction and deduction of the mystery in which they had been wrapped, and make it clear that scientific brains do not differ essentially from ordinary brains. Yet there is a line of division between Cuvier and the detective, between the lady with the stained dress and Adams and Leverrier. Cuvier inferred from the osseous structure of the Montmartre fragments that the fossil animal to which they belonged must have had a skeleton of a certain type. But the detective who fits a peculiar shoe into a peculiar foot-print merely fastens suspicion on the owner of the shoe. It is quite possible that the shoe may have been worn by some one else; a link is thus wanting in the chain of evidence. The lady guesses, with off-hand plausibility, that the stain on her dress has been made by ink; to prove that it is ink, she must resort