FALLACIES OF CONFUSION, 457 



2. We have now sufficiently exemplified one of 

 the principal Genera in this Order of Fallacies ; where, 

 the source of error being the ambiguity of terms, the 

 premisses are verbally what is required to support the 

 conclusion, but not really so. In the second great 

 Fallacy of Confusion they are neither verbally nor really 

 sufficient, though, from their multiplicity and confused 

 arrangement, and still oftener from defect of memory, 

 they are not seen to be what they are. The fallacy I 

 mean is that of Petitio Principii, or begging the ques- 

 tion ; including that more complex and not un- 

 common variety of it, which is termed Reasoning in a 

 Circle. 



Petitio Principii, as defined by Archbishop 

 Whately, is the fallacy " in which the premiss either 

 appears manifestly to be the same as the conclusion, 

 or is actually proved from the conclusion, or is such 

 as would naturally and properly so be proved." By 

 the last clause 1 presume is meant, that it is not sus- 

 ceptible 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 

 upon which it is itself dependent for proof, by no 

 means implies the degree of mental imbecility which 

 .might at first be supposed. The difficulty of compre- 

 hending how this fallacy could possibly be committed, 

 disappears when we reflect that all persons, even 

 philosophers, hold a great number of opinions without 

 exactly recollecting how they came by them. Be- 

 lieving that they have at sotne former time verified 



