EMPIRICAL LAWS. 43 



5. But how are we to know that an uniformity, ascer 

 tained by experience, 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 phenomenon 

 is produced : and this aggregate includes not only the cause of 

 the phenomenon, but all phenomena with which it is con 

 nected by any derivative uniformity, whether as being colla 

 teral effects of the same cause, or effects of any other cause 

 which, in all the instances we have been able to observe, 

 coexisted with it. The method affords no means of deter 

 mining which of these uniformities are laws of causation, and 

 which are merely derivative laws, resulting from those laws of 

 causation and from the collocation of the causes. None of 

 them, therefore, can be received in any other character than 

 that of derivative laws, the derivation of which has not been 

 traced; in other words, empirical laws: in which light, all 

 results obtained by the Method of Agreement (and therefore 

 almost all truths obtained by simple observation without 

 experiment) must be considered, until either confirmed by the 

 Method of Difference, or explained deductively, in other words 

 accounted for ^ pi iori. 



These empirical laws may be of greater or less authority, 

 according as there is reason to presume that they are resolv 

 able into laws only, or into laws and collocations together. 

 The sequences which we observe in the production and subse 

 quent life of an animal or a vegetable, resting on the Method 

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

 antecedents in those sequences may not be the causes of the 

 consequents, both the one and the other are doubtless, in the 

 main, successive stages of a progressive effect originating in a 



