80 PSYCHOLOGY. 



the four kinds above tabulated, which are employed. In the follow- 

 ing verses, all the allowable moods are indicated by means of mnemo- 

 nical words ; the kind of propositions used, being designated by the 

 vowels in the name ; as explained in the preceding section. 

 Fig. 1. Barbara, Celarent, Darii, Ferio-que prioris ; 

 Fig. 2. Cesare, Camestres, Festino, Baroko, secimdaj; 

 Fig. 3. Tertia Darapti, Disamis, Datisi, Felapton, 



Bokardo, Feriso, habet: quarta insuper addit. 

 Fig. 4. Bramantip, Camenes, Dimaris, Fesapo, Fresison 

 The example last given, concerning trees and plants, is in the mood 

 Barbara ; all three of its propositions being universal and affirmative ; 

 universal as regards their quantity, and affirmative in regard to 

 quality. An Enthymeme, is a syllogism, abridged by suppressing 

 one of the premises ; as, every tree is a plant, and therefore combus- 

 tible. An Epichirema, is a compound argument, in which the pre- 

 mises are separately proved by syllogisms, before drawing from them 

 the final conclusion. A Dilemma, is a complex or conditional syllo- 

 gism ; in which something is proved, either as still true under vary- 

 ing conditions ; or as conditionally true, under one of two or more 

 alternatives. The reductio ad impossible, and reductio ad absur- 

 dum, consist in proving something, by showing that the contrary 

 would involve either an impossibility or an absurdity. A Sorites, is 

 a series of abridged syllogisms, from which a final conclusion is derived. 

 4. A Fallacy, or Sophism, is a false argument; or else an argu- 

 ment leading to a false conclusion. The use of such arguments is 

 sometimes called sophistry ; and in complex cases, it may be very 

 difficult to detect. When the premises are false, or unsupported, or 

 irrelevant, the fallacy is called material ; but when the error is in the 

 process of employing them, the fallacy is called logical. 



Of material fallacies, the petitio principii, or begging of the ques- 

 tion, consists in assuming that what is to be proved, is true, merely 

 by stating it in another form: as when it is said that miracles are 

 impossible ; for nothing contrary to the course of nature can possibly 

 take place. Here is assertion, and assumption ; but no proof. The 

 elenchus in orbe, or arguing in a circle, is where one thing is proved 

 by assuming a second to be true ; and this second is then seemingly 

 proved by the aid of the first. The ignorantia elenchi, or ignorance 

 of the question, is where the arguments, whether true or false, do 

 not strictly apply to it. All irrelevant matter, such as a personal 

 allusion, or an argumentum ad hominem, comes under this class. 

 The fallacy of equivocation, consists in using the same term in 

 two different senses : as if we should say, light is opposed to dark- 

 ness : but feathers are light ; therefore feathers are opposed to dark- 

 ness. Here the fallacy is evident, and the conclusion absurd ; but 

 there are other cases, where the conclusion may be plausible, and the 

 fallacy very difficult of detection ; especially in the midst of a sorites 

 or protracted argumentation. 



The fallacy of composition, assumes that to be true generally, 

 which is only so in a restricted sense. The reverse of this, or fallacy 

 of division, assumes that to be true, in a particular case, which is 

 not so in that case, though it may be in similar ones. The fallacy of 



