FALLACIES OF CONFUSION. , 571 



sion, or is actually proved from the conclusion, or is such as would natu- 

 rally and properly so be proved." By the last clause I presume is meant, 

 that it is not susceptible of any other proof ; for otherwise, there would be 

 no fallacy. To deduce from a proposition propositions from which it 

 would itself more naturally be deduced, is often an allowable deviation 

 from the usual didactic order ; or at most, what, by an adaptation of a 

 phrase familiar to mathematicians, may be called a logical inelegance.^ 



The employment of a proposition to prove that on which it is itself de- 

 pendent for proof, by no means implies the degree of mental imbecility 

 which might at first be supposed. The difficulty of comprehending how 

 this fallacy could possibly be committed, disappears when we reflect that 

 all persons, even the instructed, hold a great number of opinions without 

 exactly recollecting how they came by them. Believing that they have at 

 some former time verified them by sufficient evidence, but having forgotten 

 what the evidence was, thoy may easily be betrayed into deducing from 

 them the very propositions which are alone capable of serving as premises 

 for their establishment. "As if," says Archbishop Whately, "one should 

 attempt to pi'ove the being of a God from the autliority of Holy Writ;" 

 which might easily happen to one with whom both doctrines, as funda- 

 mental tenets of his religious creed, stand on the same ground of familiar 

 and traditional belief. 



Arguing in a circle, however, is a stronger case of the fallacy, and im- 

 plies more than the mere passive reception of a premise by one who does 

 not remember how it is to be proved. It implies an actual attempt to 

 prove two propositions reciprocally from one another; and is seldom re- 

 sorted to, at least in express terms, by any person in his own speculations, 

 but is committed by those who, being hard j^ressed by an adversary, are 

 forced into giving reasons for an opinion of which, when they began to ar- 

 gue, they had not sufficiently considered the grounds. As in the following 

 example from Archbishop Whately : " Some mechanicians attempt to prove 

 (what they ought to lay down as a probable but doubtful hypothesis)} that 

 every particle of matter gravitates equally : ' why V ' because those bodies 

 which contain more particles ever gravitate more strongly, i. e., are heav- 

 ier :' ' but (it may be urged) those which are heaviest are not always more 

 bulky ;' ' no, but they contain more particles, though more closely con- 

 densed :' ' how do you know that ?' ' because they are heavier :' ' how does 

 that prove it ?' ' because all particles of matter gravitating equally, that mass 

 which is specifically the heavier must needs have the more of them in the 

 same space.' " It appears to me that the fallacious reasoner, in his piivate 

 thoughts, would not be likely to proceed beyond the first step. He would 

 acquiesce in the sufficiency of the reason first given, "bodies which contain 

 more particles are heavier." It is when he finds this questioned, and is 

 called upon to prove it, without knowing how, that he tries to establish his 



* In his later editions, Archbishop Whately confines the name of Petitio Principii "to 

 those cases in which one of the premises either is manifestly the same in sense with the con- 

 clusion, or is actually proved from it, or is such as the persons you are addressing are not 

 likely to know, or to admit, except as an inference from the conclusion; as, e.g., if any one 

 should infer the authenticity of a certain history, from its recording such and such facts, the 

 reality of which rests on the evidence of that history." 



t No longer even a probable hypothesis, since the establishment of the atomic theory ; it 

 being now certain that the integral particles of different substances gravitate unequally. It 

 is true that these particles, though real minima for the purposes of chemical combination, may 

 not be the ultimate particles of the substance ; and this doubt alone renders the hypothesis 

 admissible, even as an hypothesis. 



