Imágenes de páginas

they may be in directing our labours) can supersede the necessity.” D. Stewart, Phil. Vol. II. chap. ii. s. 2.

Nothing perhaps tends more to conceal from men their imperfect conception of the meaning of a term, than the circumstance of their being able fully to comprehend a process of reasoning in which it is involved, without attaching any distinct meaning at all to that Term; as is evident when X Y Z are used to stand for Terms, in a regular Syllogism: thus a man may be familiarized with a Term, and never find himself at a loss from not comprehending it; from which he will be very likely to infer that he does comprehend it, when perhaps he does not, but employs it vaguely and incorrectly; which leads to fallacious Reasoning and confusion. It must be owned, however, that many Logical writers have, in great measure, brought on themselves the reproach in question, by calling Logic “ the right use of Reason,” laying down “ rules for gaining clear ideas,” and such-like åraçwvela, as Aristotle calls it. (Rhet. Book I. Chap. ii.)

Material Fallacies.

$ 3. The remaining class (viz. where the Conclusion does follow from the Premises) may be called the Material, or Non-logical Fallacies:

of these there are two kinds ; * 1st. when the Premises are such as ought not to have been assumed; 2d. when the Conclusion is not the one required, but irrelevant; which Fallacy is called “ignoratio elenchi,because your Argument is not the “ elenchus" (i.e. proof of the contradictory) of your opponent's assertion, which it should be; but proves, instead of that, some other proposition resembling it. Hence, since Logic defines what Contradiction is, some may choose rather to range this with the Logical Fallacies, as it seems, so far, to come under the jurisdiction of that art; nevertheless, it is perhaps better to adhere to the original division, both on account of its clearness, and also because few would be inclined to apply to the Fallacy in question the accusation of being inconclusive, and consequently illogical reasoning: besides which, it seems an artificial and circuitous way of speaking, to suppose in all cases an opponent and a contradiction ; the simple statement of the matter being this,- I am required, by the circumstances of the case, (no matter why) to prove a certain Conclusion; I prove, not that, but one which is likely to be mistaken for it;in this lies the Fallacy.

* For it is manifest that the fault, if there be any, must be either 1st. in the Premises, or 2dly. in the Conclusion, or 3dly, in the Connexion between em.

It might be desirable therefore to lay aside the name of ignoratio elenchi,” but that it is so generally adopted as absolutely to require some mention to be made of it. The other kind of Fallacies in the Matter will comprehend (as far as the vague and obscure language of Logical writers will allow us to conjecture) the fallacy of “non causa pro causa,and that of “petitio principii:of these, the former is by them distinguished into

a non vera pro vera,and “ a non tali pro tali;” this last would appear to be arguing from a case not parallel as if it were so; which, in Logical language, is, having the suppressed Premiss false ; for it is in that the parallelism is affirmed; and the “ pro vera” will in like manner signify the expressed Premiss being false; so that this Fallacy will turn out to be, in plain terms, neither more nor less than falsity (or unfair assumption) of a Premiss.

The remaining kind,petitio principii,(begging the question,) takes place when a Premiss, whether true or false, is either plainly equivalent to the Conclusion, or depends on it for its own reception. It is to be observed, however, that in all correct Reasoning the Premises must, virtually, imply the Conclusion ; so that it is not possible to mark precisely the distinction between

non vera

the Fallacy in question and fair Argument; since that may be correct and fair Reasoning to one person, which would be, to another, “begging the question ;” inasmuch as to one, the Conclusion might be more evident than the Premiss, and to the other, the reverse.

The most plausible form of this Fallacy is arguing in a circle; and the greater the circle, the harder to detect.

§ 4.

There is no Fallacy that may not properly be included under some of the foregoing heads : those which in the Logical treatises are separately enumerated, and contradistinguished from these, being in reality instances of them, and therefore more properly enumerated in the subdivision thereof; as in the scheme annexed :




Purely-logical. ($ 7.)


Premiss unduly assumed. Conclusion irrelevant. (i. e. where the fallaciousness is appa- (the middle term being am

(ignoratio elenchi.) rent from the mere form of expression.) biguous in sense.)

($ 13.)

(§ 14.) Undistributed middle. Illicit process, &c.

(Petitio principii.) Premiss Premiss false or in itself,

from the context,

depending on the Con unsupported.

clusion. accidentally. from some connexion between

circle. the different senses.

assuming a proposition not the very same as the ques

tion, but unfairly implying resemblance. analogy. cause and effect, &c.

it. ($ 11.)

(s 12.)
Fallacy of Division and fallacia acciden-

tis, &c.
($ 17.)
($ 16.)
($ 15.)

($ 15.)
Fallacy of Fallacy of shifting ground. Fallacy of using com Fallacy of appeals to the passions; ad
objections, &c.

plex and general Terms. hominen ; ad verecundiam, &c. to something wholly irre from Premiss

to Premiss levant.


« AnteriorContinuar »