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$ 187. Substitutions of terms may consist either in the substitution of a new vocable or vocal sign, or in the substitution of a new sense to the same vocable. The latter is always illicit, and constitutes the Fallacy of Equivocation. The former will be considered in this, the latter in our next chapter.

The substitution of new terms of equivalent signification for terms originally occurring is the most common and extensive in application of all the processes involved in ratiocination; and the corresponding illicit processes — if we include equivocation — may be regarded as including all fallacies whatever. Hence the examples already given, and especially those given under the head of Irrelevant Conclusion, will serve equally well to illustrate the fallacy now under consideration.

Examples $ 188. Austin's ARGUMENT. – Many examples of this fallacy are furnished by Austin, as, e.g., in substituting for the predicate of the proposition that “ The sovereign power is incapable of legal limitation,the term legally despotic," and thus inferring from the former proposition that government is vested by law with despotic power; which is not only untrue, but upon his own theory impossible. For, if law is but an expression of the will of the sovereign, it is equally absurd to say either that the sovereign poweris limitedor that " it is conferred" by law.

$ 189. SPENCER'S ARGUMENT. - Another example is furnished by Spencer in inferring from the “ right of free exchange " the “ right of free contract," which is in effect to substitute genus for species in the subject of a universal affirmative proposition. For exchange is only a species of contract (v. supra, $ 181). It is true that the right of free contract cannot be doubted, but the substitution is none the less a logical fallacy.

$ 190. FLETCHER vs. PECK.-Still another example of this fallacy is furnished by ChiefJustice Marshall (the greatest and most logical of American jurists) in Fletcher vs. Peck, 6 Cranch, 135; where it was decided that an act of the Legislature of Georgia revoking a grant of land was in contravention of the provision of the Constitution of the United States forbid. ding the States to pass any act impairing the obligation of contracts." The argument in effect was that a grant is a contract, and that this was impaired by the act; which was in effect to substituteContractfor Obligation of Contract." The fallacy is the more glaring from the fact that a grant is an executed contract, which carries with it no obliga. tion. Hence the constitutional provision must be held to refer only to executory or obligatory contracts.

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§ 191. The ambiguity of terms and sentences (Homonymia et Amphibolia) is undoubtedly the most prolific of all sources of fallacy. This is recognized by all logicians, and, indeed, by philosophers generally; but we doubt that many appreciate the extent of the evil or the universality of the danger to which men are exposed by reason of it, or (especially) their own infirmity in this respect.

“ Instances of this fallacy,” says Mr. Mill,

are to be found in most all the argumentary discourses of unprecise thinkers”; a proposition true in its literal statement but false in its obvious implications; for it implies that the proposition is not true of precise thinkers, and also (though with becoming modesty) that it is not true of the author. But in fact the most precise, or, as we would prefer to say, the most logical thinkers are liable to fallacy, and especially to this kind of fallacy; and none

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more so than Mr. Mill.' In this respect, if fallacies be regarded as intellectual sins, we may say: “ There are none righteous. No, not one.” For it is with logicians as with generals: the best that can be said of them is, that the greatest are those who commit the fewest blunders. Hence the only difference, other than degree, between the more precise or logical thinker and the unprecise is, that the fallacies of the latter are difficult, those of the former easy to expose. Hence it may be said that, while it is the greatest achievement to be right, it is no mean achievement to be clearly and unequivocally wrong, i. e., perspicuous in our errors. Hence the value of the political theories of Hobbes and Austin, the most logical of modern writers; which, though false, and even pernicious, are yet full of instruction.

Nor is the proportion of men of great logical genius so large as is generally supposed. They are in fact as scarce as great generals, or great statesmen, or great poets. Nor is it to be as

, sumed that philosophical writers are less liable to this and other fallacies than the less pretentious classes. “ For it is most true, as Cicero saith of them somewhere, that there can be nothing so absurd but may be found in the books of the Philosophers” (Hobbes, Lev.,chap.

1 This is very fully shown by Mr. Jevons (Pure Logic and Minor Works, p. 201).

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