CLASSIFICATION AND THE PREDICABLES. 



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the same stock. That, however, is a 

 sense artificially given to the word, 

 for the technical purposes of a parti- 

 cular science. To the logician, if a 

 negro and a white man differ in the 

 same manner (however less in degree) 

 as a horse and a camel do, that is, if 

 their differences are inexhaustible, 

 and not referrible to any common 

 cause, they are different species, 

 whether tihey are descended from 

 common ancestors or not. But if 

 their differences can all be traced to 

 climate and habits, or to some one or 

 a few special differences in structure, 

 they are not, in the logician's view, 

 specifically distinct. 



When the infima species, or proxi- 

 mate Kind, to which an individual 

 belongs, has been ascertained, the 

 properties common to that Kind in- 

 clude necessarily the whole of the 

 common properties of every other real 

 Kind to which the individual can be 

 referrible. Let the individual, for 

 example, be Socrates, and the proxi- 

 mate Kind, man. Animal, or living 

 creature, is also a real Kind, and in- 

 cludes Socrates ; but, since it likewise 

 includes man, or, in other words, since 

 all men are animals, the properties 

 common to animals form a portion of 

 the conmion properties of the sub- 

 class, man. And if there be any class 

 which includes Socrates without in- 

 cluding man, that class is not a real 

 Kind. Let the class, for example, be 

 flat -nosed ; that being a class which 

 includes Socrates, without including 

 all men. To determine whether it is 

 a real Kind, we must ask ourselves 

 this question : Have all flat-nosed 

 animals, in addition to whatever is 

 implied in their flat noses, any com- 

 mon properties, other than those 

 which are common to all animals 

 whatever ? If they had ; if a flat nose 

 were a mark or index to an indefinite 

 number of other peculiaritie?, not 

 deducible from the former by an as- 

 certainable law, then out of the class 

 man we might cut another class, flat- 

 nosed man, which, according to our 

 definition, would be a Kind. But if , 



we could do this, man would not be, 

 as it was assumed to be, the proxi- 

 mate Kind. Therefore, the properties 

 of the proximate Kind do comprehend 

 those (whether known or unknown) of 

 all other Kinds to which the indivi- 

 dual belongs ; which was the point 

 we undertook to prove. And hence, 

 every other Kind which is predicable 

 of the individual, will be to the proxi- 

 mate Kind in the relation of a genus, 

 according to even the popular accepta- 

 tion of the terms genus and species ; 

 that is, it will be a larger class, in- 

 cluding it and more. 



We are now able to fix the logical 

 meaning of these terms. Every class 

 which is a real Kind, that is, which 

 is distinguished from all other classes 

 by an indeterminate multitude of 

 properties not derivable from one an- 

 other, is either a genus or a species. 

 A Kind which is not divisible into 

 other Kinds cannot be a genus, be- 

 cause it has no species under it ; but 

 it is itself a species, both with refer- 

 ence to the individuals below and to 

 the genera above (Species Priedica- 

 bilis and Species Subjicibilis). But 

 every Kind which admits of division 

 into real Kinds (as animal into mam- 

 mal, bird, fish, &c., or bird into 

 various species of birds) is a genus to 

 all below it, a species to all genera in 

 which it is itself included. And here 

 we may close this part of the discus- 

 sion, and pass to the three remaining 

 predicables, Difierentia, Propriunu 

 and Accidens. 



§ 5. To begin with Differentia. 

 This word is correlative with the 

 words genus and species, and, as all 

 admit, it signifies the attribute which 

 distinguishes a given species from 

 every other species of the same genus. 

 This is so far clear : but we may still 

 ask, which of the distinguishing attri- 

 butes it signifies. For we have seen 

 that every Kind (and a species must 

 be a Kind) is distinguished from other 

 Kinds, not by any one attribute, but 

 by an indefinite number. Man, for 

 instance, is a species of the genus 



