CLASSIFICATION AND THE PKEDICABLES. 99 



as consequences, under laws of nature, from a small number of primary 

 differences which can be precisely determined, and which, as the phrase is, 

 account for all the rest. If this be so, these are not distinctions in kind ; 

 no more than Christian, Jew, Mussulman, and Pagan, a difference which 

 also carries many consequences along with it. And in this way classes are 

 often mistaken for real Kinds, which are afterward proved not to be so. 

 But if it turned out that the differences were not capable of being thus ac- 

 counted for, then Caucasian, Mongolian, Negro, etc., would be really differ- 

 ent Kinds of human beings, and entitled to be ranked as species by the 

 logician ; though not by the naturalist. For (as already noticed) the word 

 species is used in a different signification in logic and in natural history. 

 By the naturalist, organized beings are not usually said to be of different 

 species, if it is supposed that they have descended from the same stock. 

 That, however, is a sense artificially given to the word, for the technical 

 purposes of a particular 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 they 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 struc- 

 ture, they are not, in the logician's view, specifically distinct. 



When the infima species, or proximate Kind, to which an individual 

 belongs, has been ascertained, the properties common to that Kind include 

 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 proximate Kind, man. Animal, or living creature, is 

 also a real kind, and includes Socrates ; but, since it likewise includes man, 

 or in other words, since all men are animals, the properties common to ani- 

 mals form a portion of the common properties of the sub-class, man. And 

 if there be any class which includes Socrates without including man, that 

 class is not a real Kind. Let the class, for example, be flat-nosed ; that 

 being a class which includes Socrates, Avithout including all men. To de- 

 termine 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 common 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 peculiarities, not deducible from the former by 

 an ascertainable 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 w^e 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 compre- 

 hend those (whether known or unknown) of all other Kinds to which the 

 individual belongs ; which was the point we undertook to prove. And 

 nenco, every other Kind which is predicable of the individual, will be to 

 :he proximate Kind in the relation of a genus, according to even the popu- 

 ar acceptation of the terms genus and species ; that is, it will be a larger 

 )lass, including it and more. 



We are now able to fix the logical meaning of these terms. Every class 

 vhich is a real Kind, that is, Avhich is distinguished from all other classes 

 )y an indeterminate multitude of properties not derivable from one an- 

 )ther, is either a genus or a species. A Kind which is not divisible into 

 >ther Kinds, can not be a genus, because it has no species under it ; but it 

 3 itself a species, both with reference to the individuals below and to the 



