AND ON LOGIC IN GENERAL. 



183 



I will take an example from one of the unusual forms of syllogism. Say " The time is 

 past in which the transmission of news can be measured by the speed of animals or even of 

 steam ; for the telegraph is not approached by either." Is this a syllogism ? Many would 

 say it is not ; but wrongly. Throw out the charges, the modal reference to past falsehood and 

 present truth, the advantage of the telegraph, its superior speed, the reference to progress 

 conveyed in even — and we rub off the whole design of the picture. But the ground which 

 carried the design is a syllogism. In old form it is Darapti, awkwardly. 



All telegraph speed is (not steam speed) 

 All telegraph speed is (not animal speed) 

 Therefore Some (not animal speed) is (not steam speed). 



In the system which admits contraries it is a syllogism with two negative premises, and 

 a form of conclusion unknown to Aristotle: it is, in the symbols I use, the deduction of )( 

 from )•()•( 



No animal speed is telegraph speed 

 No steam speed is telegraph speed 

 Therefore Some speed is neither animal nor steam speed. 



When this is presented, a person would naturally ask, What then ? The answer to this question 

 is seen when the charges are restored, and the sentence takes its proper place in the whole 

 argument. 



V. A great objection has been raised to the employment of mathematical symbols : and it 

 seems to be taken for granted that any symbols used by me must be mathematical. The truth 

 is that I have not made much use of symbols actually employed in algebra ; and the use which 

 I have made is in one instance seriously objectionable, and must be discontinued. But it has 

 been left to me to discover this mistake, into which I was led, as I shall shew, by the ordinary 

 school of logicians. If A and B be the premises of a syllogism, and C the conclusion, the 

 representation A + B = C is faulty in two points. The premises are compounded, not aggre- 

 gated ; and AB should have been written : the relation of joint premises to conclusion is 

 that (speaking in extension) of contained and containing, and AB<C should have been the 

 symbol. Nevertheless, A + B = C, with all its imperfections, made a suggestion of remarkable 

 character to an inventive friend of mine: while AB<C was both a suggestio veri and a sup- 

 pressio falsi to myself. For these things see the second part of this paper. 



As to symbols in general, it is not necessary to argue in their favour : mine or better ones 

 will make their way, under all the usual difficulties of new language. There was a time when 

 logic had more peculiar symbols than algebra. Every system of signs, before it has become 

 familiar, as we all remember when we look back to ABC, is repulsive, difficult, unmeaning, 

 full of signs of difference which are practical synonymes^' by combination of want of com- 

 prehension with ignorance of the want. But it is too certain to need argument that the 

 separation of form and matter requires as many symbols as there are separations. 



• A Cambridge tutor of high reputation was once trying 

 to familiarise a beginner with the difference between na and o". 

 After repeated illustration, he asked the pupil whether he saw 

 the point. " Thank you very much, Mr " was the answer ; 



" I now see perfectly what you mean : but, Mr — -, between 

 ourselves, now, and speaking candidly, don't you think it's a 

 neediets refinement." 



