COEXISTENCES INDEPENDENT OF CAUSATION. 131 



regulated) being more eminently modifiable, that is, 

 liable to be influenced by a greater number and 

 variety of causes, than any other phenomena whatever ; 

 having, moreover, themselves had a beginning, and 

 therefore a cause ; there is reason to believe that none 

 of their properties are ultimate, but all of them deri- 

 vative, and produced by causation. And the pre- 

 sumption is confirmed by the fact that the properties 

 which vary from one individual to another, also gene- 

 rally vary more or less at different times in the same 

 individual; which variation, like any other event, sup- 

 poses a cause, and implies, consequently, that the 

 properties are not independent of causation. 



If, therefore, blackness be merely accidental in 

 crows, and capable of varying while the Kind remains 

 the same, its presence or absence is doubtless no 

 ultimate fact, but the effect of some unknown cause ; 

 and in that case the universality of the experience 

 that all crows are black is sufficient proof of a common 

 cause, and establishes the generalization as an empi- 

 rical law. Since there are innumerable instances in 

 the affirmative, and hitherto none at all in the nega- 

 tive, the causes on which the property depends must 

 exist everywhere in the limits of the observations 

 which have been made ; and the proposition may be 

 received as universal within those limits, and with the 

 allowable degree of extension to adjacent cases. 



7. If, in the second place, the property, in the 

 instances in which it has been observed, is not 

 an effect of causation, it is a property of Kind; 

 and in that case the generalization can only be set 

 aside by the discovery of a new Kind of crow. 

 That, however, a peculiar Kind, not hitherto dis- 

 covered, should exist in nature, is a supposition so 



K 2 



