ERKOR AND FALLACIES 



2 95 



of the various canons and conditions of correct thinking, the 

 more common violations of the latter. But that was only in 

 passing ; and the whole subject of Fallacies demands for itself a 

 separate and more explicit treatment. 



A systematic classification, however, of the ways in which the 

 human mind can fall into error, seems to be, from the nature of 

 the case, practically if not absolutely impossible ; for error con 

 forms to no laws. Of course it breaks laws, the laws that would, 

 if observed, conduct to truth ; and hence we may attempt to 

 classify the heads or sources of error according to the laws or 

 canons violated by the mind in reaching the error. This is the 

 plan adopted by Professor Welton. 1 It suffers, in common with 

 other classifications, from this drawback, that the same individual 

 example of an error, arrived at through a certain process of thought, 

 may be referred to different heads or types of fallacy, may be 

 traced to the violation of different logical principles. This diffi 

 culty, of referring concrete cases to their proper headings, is present 

 in every scheme whether of attempted classification, or of mere 

 enumeration of the various types of fallacy. Apart from this 

 difficulty, however, of referring individual instances to a type, it 

 would seem practically impossible to give an entirely exhaustive 

 catalogue of the types themselves, the kinds of fallacious thought- 

 processes in which the mind may become involved ; because 

 there are possible sources of error peculiar to every new depart 

 ment into which we may carry our search after truth. We must, 

 then, only endeavour to notice at least all the more important and 

 common forms of deception incident to such investigation. 



With the special sources of error involved in the subject-matter of this 

 or that particular science it is not, of course, the function of logic to deal, 

 but only with common sources. Still, this must not be pressed too far. We 

 have already followed the workings of reason a certain distance into various 

 kinds of subject-matter, into the matter of induction, into that of deduction, into 

 the reasoning process known as the Aristotelean syllogism, and into certain 

 analogous forms of mediate reasoning (192) ; and we have seen that every 

 where, even in the mental act of judgment, the form assumed by our thought- 

 process depends to a certain extent upon the matter thought about (10, 81). 

 Hence there will be certain sources of error certain misconceptions, mistakes, 

 and ambiguities peculiar to the investigation of this or that particular subject- 

 matter. The reason of this is partly, at least because the different kinds of 

 subject-matter call forth different types or forms of reasoning, in accordance 

 with certain axioms that involve conceptions or intuitions of certain systems of 

 relations such as those of space, time, or quantitative proportion on which 



1 op. cit., ii., bk. vii. 



