FREE BOOKS

Author's List




PREV.   NEXT  
|<   71   72   73   74   75   76   77   78   79   80   81   82   83   84   85   86   87   88   89   90   91   92   93   94   95  
96   97   98   99   100   101   102   103   104   105   106   107   108   109   110   111   112   113   114   115   116   117   118   119   120   >>   >|  
re_; if _No men are exempt from ridicule, Some men are not_. Similarly, if I. is false A. is false; if O. is false E. is false. If we deny any predication about _Some S_, we must deny it of _All S_; since in denying it of _Some_, we have denied it of at least part of _All_; and whatever is false in one form of words is false in any other. On the other hand, if I. is true, we do not know that A. is; nor if O. is true, that E. is; for to infer from _Some_ to _All_ would be going beyond the evidence. We shall see in discussing Induction that the great problem of that part of Logic is, to determine the conditions under which we may in reality transcend this rule and infer from _Some_ to _All_; though even there it will appear that, formally, the rule is observed. For the present it is enough that I. is an immediate inference from A., and O. from E.; but that A. is not an immediate inference from I., nor E. from O. Sec. 3. Connotative Subalternation.--We have seen (chap. iv. Sec. 6) that if the connotation of one term is only part of another's its denotation is greater and includes that other's. Hence genus and species stand in subaltern relation, and whatever is true of the genus is true of the species: If _All animal life is dependent on vegetation, All human life is dependent on vegetation_. On the other hand, whatever is not true of the species or narrower term, cannot be true of the whole genus: If it is false that '_All human life is happy_,' it is false that '_All animal life is happy_.' Similar inferences may be drawn from the subaltern relation of predicates; affirming the species we affirm the genus. To take Mill's example, if _Socrates is a man, Socrates is a living creature_. On the other hand, denying the genus we deny the species: if _Socrates is not vicious, Socrates is not drunken_. Such cases as these are recognised by Mill and Bain as immediate inferences under the principle of Identity. But some Logicians might treat them as imperfect syllogisms, requiring another premise to legitimate the conclusion, thus: _All animal life is dependent on vegetation; All human life is animal life; .'. All human life is dependent on vegetation._ Or again: _All men are living creatures; Socrates is a man; .'. Socrates is a living creature._ The decision of this issue turns upon the question (_cf._ chap. vi. Sec. 3) how far a Logician is entitled to assume that the terms
PREV.   NEXT  
|<   71   72   73   74   75   76   77   78   79   80   81   82   83   84   85   86   87   88   89   90   91   92   93   94   95  
96   97   98   99   100   101   102   103   104   105   106   107   108   109   110   111   112   113   114   115   116   117   118   119   120   >>   >|  



Top keywords:

Socrates

 

species

 

dependent

 
vegetation
 
animal
 

living

 

relation

 
creature
 

subaltern

 

inference


inferences

 

denying

 

affirm

 
assume
 

entitled

 

affirming

 

Logician

 
question
 

Similar

 
predicates

decision

 
creatures
 

principle

 

syllogisms

 
requiring
 

Identity

 

imperfect

 

Logicians

 

recognised

 

conclusion


legitimate

 

vicious

 

premise

 

drunken

 
evidence
 

problem

 
Induction
 
discussing
 
Similarly
 

predication


ridicule

 

exempt

 

denied

 
determine
 

conditions

 

connotation

 

Subalternation

 
denotation
 

includes

 
greater