434 FALLACIES. 



have resulted from its leading by correct inference to 

 something already recognised as false. 



Again, the very frequent error in conduct, of mis- 

 taking reverse of wrong for right, is the practical form 

 of a logical error with respect to the Opposition of 

 Propositions. It is committed for want of the habit of 

 distinguishing the contrary of a proposition from the 

 contradictory of it, and of attending to the logical 

 canon, that contrary propositions, though they cannot 

 both be true, may both be false. If the error were 

 to express itself in words it would run distinctly 

 counter to this canon. It generally,, however, does 

 not so express itself, and to compel it to do so is the 

 most effectual method of detecting and exposing it. 



3. Among Fallacies of Ratiocination are to be 

 ranked, in the first place, all the cases of vicious 

 syllogism laid down in the books. These generally 

 resolve themselves into having more than three terms 

 to the syllogism, either avowedly, or in the covert 

 mode of an undistributed middle term or an illicit 

 process of one of the two extremes. It is not, indeed, 

 very easy fully to convict an argument of falling 

 under any one of these vicious cases in particular; 

 for the reason already quoted from Archbishop 

 Whately, that the premisses are seldom formally set 

 out: if they were, the fallacy would impose upon 

 nobody; and while they are not, it is almost always 

 to a certain degree optional in what manner the 

 suppressed link shall be filled up. The rules of the 

 syllogism are rules for compelling a person to be 

 aware of the whole of what he must undertake to de- 

 fend if he persists in maintaining his conclusion. He 

 has it almost always in his power to make his syllogism 

 good by introducing a false premiss; and hence it is 



