410 INDUCTION. 



adopt, are taken to constitute the class crow, or the class negro. Now, 

 supposing blackness to be an ultimate property of black objects, or woolly 

 hair an ultimate property of the animals which possess it; supposing that 

 these properties are not results of causation, are not connected with ante- 

 cedent phenomena by any law ; then if all crows are black, and all negroes 

 have woolly hair, these must be ultimate properties of the kind crow, or 

 negro, or of some kind which includes them. If, on the contrary, black- 

 ness or woolly hair be an effect depending on causes, these general propo- 

 sitions are manifestly empirical laws ; and all that has already been said 

 respecting that class of generalizations may be applied without modifica- 

 tion to these. 



Now, we have seen that in the case of all compounds — of all things, in 

 short, except the elementary substances and primary powers of nature — 

 the presumption is, that the properties do reall}^ depend upon causes; and 

 it is impossible in any case whatever to be certain that they do not. We 

 therefore should not be safe in claiming for any generalization respecting 

 the co-existence of properties, a degree of certainty to which, if the pi'op- 

 erties should happen to be the result of causes, it would have no claim. 

 A generalization respecting co-existence, or, in other words, respecting the 

 pi'operties of kinds, may be an ultimate truth, but it may also be merely a 

 derivative one ; and since, if so, it is one of those derivative laws which 

 are neither laws of causation nor have been resolved into the laws of cau- 

 sation on which they depend, it can possess no higher degree of evidence 

 than belongs to an empirical law. 



§ 4. This conclusion will be confirmed by the consideration of one great 

 deficiency, which precludes the application to the ultimate uniformities of 

 co-existence, of a system of rigorous scientific induction, such as the uni- 

 formities in the succession of phenomena have been found to admit of. 

 The basis of such a system is wanting; there is no general axiom standing 

 in the same relation to the uniformities of co-existence as the law of causa- 

 tion does to those of succession. The Methods of Induction applicable to 

 the ascertainment of causes and effects are grounded on the principle that 

 every thing which has a beginning must have some cause or other; that 

 among the circumstances which actually existed at the time of its com- 

 mencement, there is certainly some one combination, on which the effect 

 in question is unconditionally consequent, and on the repetition of which 

 it would certainly again recur. But in an inquiry whether some kind (as 

 crow) universally possesses a certain property (as blackness), there is no 

 room for any assumption analogous to this. We have no previous certain- 

 ty that the property must have something which constantly co-exists with 

 it ; must have an invariable co-existent, in the same manner as an event 

 must have an invariable antecedent. When we feel pain, we must be in 

 some circumstances under which, if exactly repeated, we should always feel 

 pain. But when we are conscious of blackness, it does not follow that 

 there is something else present of which blackness is a constant accompani- 

 ment. There is, therefore, no room for elimination ; no method of Agree- 

 ment or Difference, or of Concomitant Variations (which is but a modifi- 

 cation either of the Method of Agreement or of the Method of Difference). 

 We can not conclude that the blackness we see in crows must be an in- 

 variable property of crows merely because there is nothing else present of 

 which it can be an invariable property. We therefore inquire into the 

 truth of a proposition like "All crows are black," under the same disad- 



