principle of General Utility, and systematically uses the latter as the premise established.

$179. MISUSE OF THE THEORY OF GENERAL UTILITY. This theory, in the use habitually made of it by Bentham and by utilitarians generally, also presents a most instructive example of this fallacy. The theory, being non-significant, is in itself innocuous; but it is commonly used as equivalent to the proposition that the interest of the majority is the sole test of right, or, as expressed by Bentham,

as equivalent to the sacred truth that the greatest good of the greatest number is the foundation of morals and legislation." Thus we have the apparently innocuous principle of General Utility converted into the execrable maxim that the good of the majority is alone to be consulted.

180. BENTHAM'S DEFENCE OF USURY.Bentham's celebrated defence of usury has been commonly regarded ever since its publication as finally settling the question involved; but in fact it presents a striking example of the fallacy of Ignoratio Elenchi.

His thesis, as proposed, is to establish "the liberty of making one's own terms in money bargains"; and his conclusion, which is entirely legitimate, is that no man, not under disability,

ought to be hindered, with a view to his own advantage, from making such bargains in the

way of obtaining money as he sees fit." But obviously this is to mistake the issue; for the question is, not whether one should have the liberty of making usurious contracts, but whether he should be compelled to perform them (§ 167), and hence his conclusion is obviously irrelevant. He fails, therefore (though the world has thought differently), to establish his proposition.'

181. SPENCER'S ARGUMENT.-Spencer's argument-in Social Statics and Justice-for liberty of contract is also an example of the same fallacy. His first principle is his wellknown law of equal liberty, namely, "that every man is free to do that which he wills, provided that he infringes not the equal freedom of any other man. From this principle he deduces, with admirable logic, the several personal rights that may be summed up in the general right of self-ownership, and also the right of property, and, as a corollary to the last, the right of free exchange, and from that (illogically, 189) the right of free contract; but he illicitly assumes, with Bentham, that the

1 In these observations it will be understood we are considering, not the moral or political question as to the propriety of enforcing contracts for the payment of interest (on which we have nothing to say), but simply the logical question as to the validity of an argument in favor of usury that has served to convince mankind of its righteousness, and that is universally regarded by an unlogical world as conclusive.

question is one touching the liberty of contract, and not as to the righteousness of coercing the parties (167), which was his thesis. Hence his conclusion is essentially distinct from the real conclusion intended, which is, that men should be compelled to perform contracts.

§ 182. BERKELEY'S THEORY AS TO THE NON-EXISTENCE OF MATTER.-This furnishes

another example. His argument is that, if matter exists, it is impossible for us to know the fact, or to know anything about it. But this conclusion he habitually uses as equivalent to the proposition that "matter, in fact, does not exist," i. e., he substitutes the "nonexistence of matter" for "ignorance of its existence."

CHAPTER XIII

ILLICIT CONVERSIONS

183. SIMPLE CONVERSION OF UNIVERSAL AFFIRMATIVE PROPOSITION.-The most usual form of this fallacy occurs in the simple conversion of a universal affirmative proposition, as, e. g., where from the proposition "Y is X" we illicitly infer that "X is Y"; and to this form all other cases may be reduced. The fallacy is so obvious that it might be supposed it could not often occur, but it is in fact very

common.

Examples

184. CONFUSION OF PROPOSITION WITH JUDGMENT.—An example of it seems to be presented by the commonly received doctrine that "a proposition is a judgment expressed in words"; which seems to result from an illicit conversion of the proposition that a "judg ment expressed in words is a proposition.'

$ 185. ILLICIT CONVERSION BY NEGATION.

-The fallacy frequently occurs in the conversion of a proposition by negation or contraposition. Thus, e. g., the proposition "Y is not X" becomes by negation " Y is not-X "; from which-converting per accidens-we may infer that "Some not-X is Y"; but not—as is often inferred-that " All not-X is Y."

By this method any universal affirmative proposition ("Y is X'') may be converted into a proposition between the negatives of its terms. (i. e., Not X is not Y); but not, as is often done, without converting the terms,-i. e., from the proposition "Y is X " we may infer that Not X is not Y," but not that “Not Y is not X" (§ 91).

$186. AN ARGUMENT OF HOBBES.- A striking example of this fallacy is presented by Hobbes, that prince of logicians. Justice he defines as the keeping of covenants, and injustice as the failure to keep them. But, according to his theory, covenants become valid only upon the institution of government, from which they derive their validity. Hence in a state of nature there is neither justice nor injustice. But he says also: "Whatever is not unjust is just," and this conclusion-which is contradictory to his main position is obviously arrived at by an illicit conversion of the universal affirmative proposition, "Whatever is just is not-unjust."