FALLACIES OF CONFUSION. 511 



alone capable of serving as premisses for their establishment. An 

 example is jj^ven by Archbishop Whately : " As if one should attempt 

 to prove the being of a Giul i'nmx the authority of Holy Writ;" which 

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

 mental tenets of his religion, stand upon the same ground of familiar 

 and traditional belief. 



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

 implies more than the mere passive reception of a premiss 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 resorted to, at least in express terms, by any person in his 

 own speculations, but is committed by those who, being haixl pressed 

 by an adversary, are forced into giving reasons for an opinion of which, 

 when they began to argue, 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 liut doubtful hypothesis*) that every particle of matter 

 gravitates equally: 'why!' 'because those bodies which contain more 

 particles ever gravitate more strongly, i. e. are heavier:' 'but (it may 

 be urged), those which are heaviest are not always more bulky;' 'no, 

 but they contain more pai'ticles, though more closely condensed :' 

 ' how do you know that V 'because they are heavier :' ' how docs that 

 prove itl' 'because all particles of matter gravitating equally, that 

 mass which is specifically the heavier must needs have tlie more of 

 them in the same space.' " It appears to me that the fallacious 

 reasoner, in his private thoughts, would not be likely to proceed beyond 

 the first step.t 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 premiss by supposing 

 proved what he is attempting to prove by it. The most effectual way, 

 in fact, of exposuig a Petitio Principii, when circumstances allow of 

 it, is by challenging the reasoner to prove his premisses ; which if he 

 attempts to do, he is necessarily driven into arguing in a circle. 



It is not uncommon, however, for thinkers, and those not of the low- 

 est description, to be led, even in their own thoughts, not indeed into 

 formally proving each of two propf)sitions fxom the other, but into ad- 

 mitting propositions which can only be so proved. In the preceding 

 example the two together form a complete and consistent, though hy- 

 pothetical, explanation of the facts concerned. And the tendency to 

 mistake mutual coherency for truth ; to trust one's safety to a strong 

 chain although it has no point of sujjport ; is at the bottom of much 

 which, when reduced to the strict forms of argumentation, can exhibit 

 itself no otherwise than as reasoning in a circle. All experience bears 

 testimony to the enthralling effect of neat concatenation in a system of 



* No longfir even a probable liypothesis, but (since the establishment of the atomic 

 lheor>') opposed to all prol)ability ; it t)eing now certain tliat the integrant particles of dif- 

 ferent substances gravitiite unequally. It is true that these particles, though real minima 

 for the purposes of chemical combination, may not be the ultimate particles of the sub- 

 stance ; and this doubt alone renders the hyyolhesis admissible, even as an hypothesis. 



t I have found, however, an argument of this exact typo in a BridgewaUr Treaiine :— 

 " Ice and sijver, under the same volume, contain very unequal portions of matter, the sil- 

 ver being ten times as heavy as the ice. The vacuities in the ice, therefore, must be very 

 much greater than those in the silver." 



