COEXISTENCES INDEPENDENT OF CAUSATION. 349 



believe that none of their properties are ultimate, but all of them deriv- 

 ative, and produced by causation. And the presumption is confirmed 

 by the fact that the properties which vary from one individual to 

 anotlun-, also generally vary more or less at diflerent times in the same 

 individual ; which variation, like any other event, su})poses a cause, 

 and implies, consequently, that the properties arc not independent of 

 causation. 



If, therefore, blackness be mei'ely 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 somO 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 gener- 

 alization as an empirical law. Since there are innumerable instances 

 in the affirmative, and hitherto none at all in the negative, 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 effi^ct 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 discovered, should exist in nature, is a supposition so often 

 realized, that it cannot be considered at all improbable. We have 

 nothing to authorize us in attempting to limit the Kinds of things which 

 exist in nature. The only unlikelihood would be that a new Kind 

 should be discovered in localities which there was previously reason to 

 believe had been thoroughly explored ; and even this impi'obability 

 depends upon the degree of conspicuousness of the diffei-ence between 

 the newly discovered Kind and all others, since new Kinds of minerals, 

 plants, and even animals, previously overlooked or confounded with 

 known species, are still continually detected in the most frequented 

 situations. On this second ground, therefore, as well as on the first, 

 the observed uniformity of coexistence can only hold good as an cm])ir- 

 ical law, within the limits not only of actual observation, but of an 

 observation as accurate as the nature of the case required. And hence 

 it is that (as remarked in an early chapter of the present Book) we so 

 often give up generalizations of this class at the first summons. If any 

 credible wittiess stated that he had seen a white crow, under circum- 

 stances which made it not incredible that it should have escaped notice 

 previously, we should give full credence to the statement. 



It appears, then, that the uniformities which obtain in the coex- 

 istence of phenomena — those which wo have reason to consider aa 

 ultimate, no less than those which arise from the laws of causes yet 

 undetected — are entitled to reception only as empirical laws ; are not 

 to be presumed true except in the limits of time, place, and circum- 

 stance, in which the observations were made, or except in cases etrictly 

 adjacent. 



§ 8. We have seen in the last chapter that there is a point of gener- 

 ality at which empirical laws become as certain as laws of nature, or 

 rather, at which there is no longer any distinction between empirical 



