CORRESPONDENCE 



To the Editor of " Science Progress " 



LOGIC AND ILLOGIC 



I. From Dr. C. A. Mercier, F.R.C.P., F.R.C.S. 



Sir, — There are many inaccuracies in Mr. Winter's letter : I 

 will point out a few. It is inaccurate to say that I assailed 

 Miss Stebbing. She attacked me with some asperity, and I 

 defended myself with the meekness and gentleness that are 

 becoming towards a lady, but that must not be expected by 

 Mr. Winter. 



It is inaccurate to say that no form of words is an argu- 

 ment unless it contains a conclusion that is not specifically 

 implied in a premiss. This is exactly the reverse of the truth, 

 and can be made punctually accurate by omitting the word 

 not. Deductive argument consists in nothing but discovering 

 other meanings, besides that explicitly stated, that are implied 

 in a proposition. " If you tell us that A is greater than B, 

 you are not giving us any fresh information by saying that 

 B is less than A " — P. This is in one sense true : in another 

 sense false. The second proposition is implied in the first, but 

 is not the same as the first. It compels us to look at the same 

 fact in a different light. It introduces us to a new aspect. 

 It regards the matter from a different point of view. Just 

 so, when we move round a house from the south side to the 

 north, we are looking at the same thing, but we see it from a 

 different aspect, we have seen more of it than we saw when 

 our view was limited to one aspect. This is what deductive 

 reasoning does, and this is all it ever does or can do. It is 

 precisely what is done when " from Some German subjects are 

 Poles, we infer that Some Poles are German subjects " — Q. 

 If Q is an argument, as Mr. Winter says it is, then P is an 

 argument. If P is not an argument, as Mr. Winter says it is 



not, then Q is not an argument. 



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