222 Mr DE MORGAN, ON THE SYLLOGISM, No. Ill, 



species of attribute and attribute an essential of class, in physical reading : and attribute a 

 dependent of class, or class a genus of attribute, in contraphysical reading. We might even, 

 on occasion, join the words of the two readings, in an order reverse of what we come from and 

 what we are going to. Thus class may be a dependent species of attribute, and attribute a 

 genus essential, of class, in physical reading : while attribute may be a class dependent of class, 

 and class an essential genus of attribute, in contraphysical reading. But no advice can be 

 given on this point : such a familiarity with all the schetical words as we have with species, 

 will dictate the form of mixed reading. 



When both premises are physical, the first figure does not exist. In the second figure we 

 compare classes by reference to a common attribute : in the third figure we compare attributes 

 by reference to their relation with a common class. In the Aristotelian system, that is, con- 

 fining ourselves to propositions in which we do not expressly deal with the whole universe, the 

 second figure has no affirmative conclusion : that is, partience or inclusion cannot be inferred 

 of two classes by reference to one attribute. And the third figure has no universal conclusion; 

 that is, essentiality or repugnance of two attributes cannot be inferred by their relations to one 

 class. This is more than technical knowledge ; or would be, if duly expanded. 



When the premises are of different kinds, with middle terms of the same reading, we have 

 as follows, if we exclude the contraphysical form. The first figure yields only physical 

 conclusion, from premises mathematical and physical, or physical and metaphysical. The 

 second figure yields only physical conclusion, from premises physical and mathematical. 

 The third figure yields only physical conclusion, from premises mathematical and physical. 



The fourth figure, when both the premises are not of the same reading, and the middle 

 term of the same reading in both, cannot exist without a contraphysical proposition, either in 

 one premise or in the conclusion. 



POSTSCRIPT. 



Throughout this paper I have abstained from all mention of the name of any opponent 

 of my views. This omission would have been an unpardonable affectation if there had not 

 been a good reason for it : consequently it would appear in that light but for a good expla- 

 nation. Had I taken the usual course, the name of a personal opponent and accuser would 

 have struck the eye so often, that I should have been liable to serious misconstruction : not 

 indeed from those who should carefully read my paper, but from the much larger number who 

 would look over its pages on the way to other matter. Had I given one name its due frequency 

 of mention, I should have been supposed by the turner of the pages to be continuing that kind 

 of controversy which death should always interrupt: had I made an exception of that* name 

 only, I should have appeared to the reader as ignoring, from personal motives, a memory 

 which cannot be ignored in a branch of psychology from any worthy motives whatsoever. 



• This must be my apology to Mr Baynes, Mr Mansel, I my omission of direct allusion to them in my production of and 

 Mr Mill, Mr Spalding, Dr Thomson, and perhaps others, for | remarks on then: opinions. 



