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Grew's fallacy è consists in the inference that a vessel which carries a great quantity of canvas must move rapidly through the water. The quantity of canvas may indicate that the wind is very light, or that the vessel is so clumsy that it can make no headway without an unusual press of sail.
sign opposed by that from antecedent probability.
An argument from sign which is valid in itself may be opposed and perhaps overcome by an argument from anteArgument from cedent probability. Thus, in a thesis on the
dialect spoken in a small Canadian district,
which was settled by the French but which had for two centuries been cut off from the rest of the French-speaking world, a student argued from evidence obtained on the spot that this dialect closely resembles the Parisian French of to-day. To this argument from sign there is an obvious answer derived from the antecedent improbability that the language spoken in a remote corner of Canada would undergo exactly the same changes as that spoken in the capital of France. To overcome this argument from antecedent probability it would be necessary for the author of the thesis to prove that he thoroughly knew Parisian French, and that he made no mistake as to the Canadian dialect.
An argument of any one of the three classes just considered may be combined with other arguments of the Strength of same class or with arguments of one or both
of the other classes, each separate argument strengthening the others and being strengthened in turn by them. Those who oppose the view that Bacon wrote the works attributed to Shakspere argue from antecedent
1 This fallacy is pointed out by Coleridge, who describes the vessel
a clumsy Dutch Schooner heavily rigged, and wobbling on three knots per hour, under crowded sails.” See “Marginalia Hitherto Unpub. lished.” The (London) Athenæum, April 7, 1888, p. 435.
probability that no one man could have written all the works attributed to Shakspere and all those attributed to Bacon, and that if Shakspere had not written the works attributed to him he would not throughout his life have had the credit of writing them. They argue from sign that the works attributed to Shakspere and those ato tributed to Bacon are too unlike to be the product of the same mind. To prove that a man brought up as Shakspere was might have written the works attributed to him, they argue from example that, as Erskine, who had no legal education, yet became the first advocate of his time, and as Lincoln, though a man of small erudition, developed a literary style of great strength, and as Keats, in spite of many disadvantages, became a great poet at twenty-five, so Shakspere, being a man of remarkable natural gifts, made the most of all the material that fell in his way and learned to write by writing.
In answer to a commonly-received view as to the extinction of inferior races, arguments from antecedent probability and from example are adduced in the following passage :
“ There exists a sentiment, for the most part quite unreasonable, against the gradual extinction of an inferior race. It rests on some confusion between the race and the individual, as if the destruction of a race was equivalent to the destruction of a large number of men. It is nothing of the kind when the process of extinction works silently and slowly through the earlier marriage of members of the superior race, through their greater vitality under equal stress, through their better chances of getting a livelihood, or through their prepotency in mixed marriages. That the members of an inferior class should dislike being elbowed out of the way is another matter; but it may be somewhat brutally argued that whenever two individuals struggle for a single place, one must yield, and that there will be no more unhappiness on the whole, if the inferior yield to the superior than conversely,
whereas the world will be permanently enriched by the success of the superior. The conditions of happiness are, however, too complex to be disposed of by à priori argument; it is safest to appeal to observation. I think it could be easily shown that when the differences between the races is [sic] not so great as to divide them into obviously different classes, and where their language, education, and general interests are the same, the substitution may take place gradually without any unhappiness. Thus the movements of commerce have introduced fresh and vigorous blood into various parts of England, the new-comers have intermarried with the residents, and their characteristics have been prepotent in the descendants of the mixed marriages. I have referred in the earlier part of the book to the changes of type in the English nature that have occurred during the last few hundred years. These have been effected so silently that we only know of them by the
Arguments that strengthen one another are used in the following passage:
“The ordinary observer has many proofs of the general spherical form of the earth, among which may be mentioned the following: (1) As a vessel sails away from the land, we first lose sight of her hull, next of her lower or main sails, and lastly of her topsails and pennants, thus clearly showing that she is passing over a convex or bulging surface. (2) The reverse of this also holds true; for the mariner, as he approaches the land, first sees the mountaintops, and on gradually nearing it, the lower grounds stage by stage make their appearance. (3) Had the earth's surface been flat, it would have been all at once illuminated by the rays of the sun; but being convex or round, each place, as it turns from west to east, has its sunrise, noon, sunset, and night in succession half of the globe being thus always in light while the other is in darkness. (4) In travelling any considerable distance, either north or south, new stars gradually come into view in the direction to which the traveller is advancing, while others disappear in the direction from which he is receding. (5) Many navigators, by constantly sailing in one direction, or nearly so, whether due east or
1 Francis Galton : Inquiries into Human Faculty and its Development; Influence of Man upon Race.
due west, have returned to the port from which they set out, thus making what is termed the circumnavigation of the globe. (6) In consequence of the round form of the earth, the dip or depression of the horizon is about eight inches per mile, and on this account engineers in cutting canals have to make an allowance for a dip of this extent 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) And lastly, the earth belonging to a system or brotherhood [sic], the other members of which are globular, the fair presumption is, that she [sic] also is of the same form.” 1
From all that has been said, it is plain that experience is the basis on which every argument rests. It is experience that puts us in possession of facts All arguments and teaches us how to draw valid inferences experience. from them. Whether the foundations of belief rest ultimately upon something prior to experience or not, it is to experience that we habitually appeal. If, then, experience is, for practical purposes, the source of all arguments, it follows that absolute certainty is very rarely attainable ; for there are few matters in which experience points one way and one way only. A reasonable probability sufficiently strong to act upon is, however, usually within our reach.
The object of every argumentative composition should be to prove, or to disprove, the proposition in dispute and that proposition only. Anything that does not help to prove, or to disprove, the proposition has no place in the argument; everything that does help should be so
1 David Page: Advanced Text-Book of Physical Geography, revised and enlarged by Charles Lapworth, [chap.) ii.
stated that its bearing on the argument will be evident The first requisite of an argument is, then, unity. Next in importance are clearness and force. These three qualities have been discussed in the chapters entitled “Choice of Words,” “ Number of Words,” and “Arrangement.” What is said in those chapters applies to argument as to other kinds of composition ; but in regard to ARRANGEMENT it is necessary to add something that is applicable to argumentative composition alone.
The importance of so arranging the several parts of an argumentative composition that they may render effecImportance tive support to one another can hardly be arrangement. overestimated. Forces that might be beaten in detail will often be irresistible if skilfully drawn up and massed at the points of danger. Recognizing this fact, Demosthenes at the beginning of his “Oration on the Crown” demanded from his judges, as a condition of fair play, freedom in the arrangement as well as in the selection of his arguments. Had he been obliged to adopt the arrangement of his adversary Æschines, as Æschines desired, he would necessarily have given undue prominence to the arguments of his adversary and undue subordination to his own.
“ You shall find,” says John Quincy Adams, “hundreds of persons able to produce a crowd of good ideas upon any subject, for one that can marshal them to the best advantage. Disposition [methodical arrangement] is to the orator what tactics, or the discipline of armies, is to the military art. And as the balance of victory has almost always been turned by the superiority of tactics and of 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.” ?
1 J. Q. Adams: Lectures on Rhetoric and Oratory, lect. vii.