EMPIRICAL LAWS. 369 



they have beeu found true by observation ; and not merely the limits of 

 time and place, but of time, place, and circumstance ; for, since it is the very 

 meaning of an empirical law that we do not know the ultimate laws of cau- 

 sation on which it is dependent, we can not foresee, without actual trial, in 

 what manner or to what extent the introduction of any new circumstance 

 may affect it. 



§ 5. But how are we to know that a uniformity ascertained by experi- 

 ence is only an empirical law ? Since, by the supposition, we have not been 

 able to resolve it into any other laws, how do we know that it is not an 

 ultimate law of causation ? 



I answer that no generalization amounts to more than an empirical law 

 when the only proof on which it rests is that of the Method of Agreement. 

 For it has been seen that by that method alone we never can arrive at 

 causes. The utmost that the Method of Agreement can do is, to ascertain 

 the whole of the circumstances common to all cases in which a phenome- 

 non is produced ; and this aggregate includes not only the cause of the 

 phenomenon, but all phenomena with which it is connected by any deriva- 

 tive uniformity, whether as being collateral effects of the same cause, or 

 effects of any other cause which, in all the instances we have been able to 

 observe, co-existed with it. The method affords no means of determining 

 which of these uniformities are laws of causation, and which are merely 

 derivative laws, resulting from those laws of causation and from the collo- 

 cation of the causes. None of them, therefore, can be received in any oth- 

 er character than that of derivative laws, the derivation of which has not 

 been traced ; in other words, empirical laws : in which light all results ob- 

 tained by the Method of Agreement (and therefore almost all truths obtain- 

 ed by simple observation without experiment) must be considered, until 

 either confirmed by the Method of Difference, or explained deductively; in 

 other words, accounted for a priori. 



These empirical laws may be of greater or less authority, according as 

 there is reason to presume that they are resolvable into laws only, or into 

 laws and collocations together. The sequences which we observe in the 

 production and subsequent life of an animal or a vegetable, resting on the 

 Method of Agreement only, are mere empirical laws ; but though the ante- 

 cedents in those sequences may not be the causes of the consequents, both 

 the one and the other ai*e doubtless, in the main, successive stages of a pro- 

 gressive effect originating in a common cause, and therefore independent 

 of collocations. The uniformities, on the other hand, in the order of super- 

 position of strata on the earth, are empirical laws of a much weaker kind, 

 since they not only are not laws of causation, but there is no reason to be- 

 lieve that they depend on any common cause ; all appearances are in favor 

 of their depending on the particular collocation of natural agents which at 

 some time or other existed on our globe, and from which no inference can 

 be drawn as to the collocation which exists or has existed in any other por- 

 tion of the universe. 



§ 6. Our definition of an empirical law, including not only those uniform- 

 ities which are not known to be laws of causation, but also those which are, 

 provided there be reason to presume that they are not ultimate laws ; this 

 is the proper place to consider by what signs we may judge that even if an 

 observed uniformity be a law of causation, it is not an ultimate, but a deriv- 

 ative law. 



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