due east or due west, have returned to the port from which they set out, making a circumnavigation of the globe. (6) Engineers in cutting canals have to make an allowance for a dip of about eight inches a mile in order to keep the water at a uniform level. (7) The shadow which the earth casts on the moon during an eclipse is always circular. (8) The earth belonging to a system, the other members of which are globular, the fair presumption is, that it also is of the same form. ” Corrobora In the above case the inference from each fact or phenomenon taken as a sign, being the effect of a single necessary cause or condition, is rather corroborated than strengthened by combination with the others. tion or Rein- The force of the combination is not more forcement. than the sum of the force of all the single arguments. In many cases, however, it is not so much. the accumulation of inferences from sign, as the combination of signs in a peculiar way, that gives cogency to the whole. The force of the arguments in combination is much more than the sum of their force when taken singly. Each circumstance offered in evidence against Vanderpool1 could be plausibly explained on the theory of his innocence, had this circumstance occurred alone. It was the connection of the circumstances that convinced the first jury of the prisoner's guilt. The same is true of the circumstances upon which the Knapps were convicted of Captain White's murder. A peculiar inference from an accumulation or a succession of signs is that called the argument from Progressive Tendency. This is the proof of a part of the law of inertia, "A body once set in motion, will continue in motion in a right line, with a uniform velocity, 1 Page 51. unless acted on by some force tending to accelerate, retard, stop or divert it." This is incapable of direct proof, since all bodies in motion are subject to more than a single force. But just in proportion Tendency. as all forces but one are eliminated, the law Progressive is verified. A ball rolls farther on a smooth surface than on a rough one: and the smoother the surface, the farther the ball will roll. A pendulum swings longer and a wheel continues longer in motion as the friction at the point of support is removed and the resistance of the air is overcome. This argument has been used to prove the attributes of Deity. Not only do the most enlightened and intellectually cultivated nations agree as to these attributes, but just in proportion as nations advance in enlightenment and culture, so they recognize these attributes. There is, moreover, a progressive tendency to recognize the highest attributes of Divinity, as individuals recede from a savage state and advance in civilization. 1 ment based The basis of all these arguments is experience, either our own or the authenticated experience of another substituted for our own. Whatever may be the ultimate foundations of belief, we always appeal to ex- All Arguperience. The more facts from this source on Experiwe have in our possession, the richer and ence. more apt will be our material for arguments. In accumulating facts from experience we learn also how to draw valid inferences from them. He who would convince others must, of course, have in his possession all the necessary facts pertaining to the case in hand; but almost all kinds of knowledge beyond this special case 1 See Whately, Rhetoric, 106. can be drawn upon for argument and illustration. It is this outside, general knowledge that is likely to be common to the arguer and those whom he wishes to convince. The facts of this specific matter he may have to communicate. The sources of knowledge useful to the arguer are almost innumerable. The impressions made upon men's minds by experience and its substitutes,-observation, reading, the testimony of others, Sources of relate to Nothing Knowledge. nearly everything in the universe. 1 Abridged from Robinson's Forensic Oratory, 92. 4 V. SEQUENCE OF ARGUMENTS. The sequence of arguments 1 is of scarcely less importance than their character. The reasoner collects arguments from every available source. From these he selects such as will be most cogent, taking Importance into account the character of his auditors, of Good their attitude toward his case, and toward Sequence. himself. These he must arrange so as to give each its fullest effect, and make it render to others its fullest support. The ideas calculated to awaken interest in the arguer and in his case, are supposed to have been presented in the introduction. The ideas which reveal the nature of the proposition and the arguer's claims for it, are understood to have been expressed in the partition,2 or announced plan. It remains to present in the body of the discourse arguments of such kinds and in such order as will most fully establish the proposition, and justify the arguer's claims. The Greek orators laid great stress on the arrangement of arguments: "Another of his (Isæus's) strong points was his arrangement of materials, moving his forces with a rapidity and a skill which threw the stress of the assault upon the enemy's weakest points. This is an art which the ancients prized as much in oratory as in war; so much that a disputant Orators. used to demand of the judges that his own order Greek be adhered to by the speaker who was to follow, as Eschines did when Demosthenes was about to demolish him. Therefore Isæus varies his disposition of argument according to present need, like a master of arts instead of a servant of rules. Sometimes he drops the introduction altogether and begins with a 1 This must not be confused with the grouping of proofs, page 22. 2 Pages 16, 194. brief statement of the case with unconventional abruptness. Again he makes the narrative short or long, as he chooses, combining luminous recital with perspicuous reasoning, going step by step through the argument, satisfied with nothing but a systematic and vigorous demonstration, laying close siege to the understanding of the judges. Sometimes he convinces without persuasion, though he seldom persuades without convincing."1 Force Gained ment. The whole body of arguments must, like a good sentence or paragraph, possess clearness and unity; and more than any other form or part of composition, it must possess force. Its purpose is to induce belief or by Arrange- change belief, to compel the acceptance of a truth or the abandonment of an error. Arrangement has much to do with securing this force. We have seen that arguments gain, not only by accumu lation but by their connection. But the battle is not to the strong alone; it is to the active, the vigilant, the brave. "Forces that might be easily beaten in detail, will often be irresistible if skillfully drawn up and massed at the point of danger." The gathering of an army is one thing; the instruction, discipline and successful management of an army in a hotly contested battle, is quite another. "As the balance of victory has almost always been turned by the superiority of tactics and discipline, so the great effects of eloquence are always produced by the excellency of disposition. There is no part of the science in which the consummate orator will be so decidedly marked out as by the perfection of his disposition."2 This military analogy may be carried farther. There is both an independent and an auxiliary use for infantry, cavalry, artillery. There is superior gun metal, superior ammunition, 1 Sears, History of Oratory, 56. 2 John Quincy Adams. |