EMPIRICAL LAWS. 55 



laws of causation at all. So long as these are unre- 

 solved, we cannot tell upon how many collocations, as 

 well as laws, their truth may be dependent ; and can 

 never, therefore, extend them with perfect confidence 

 to cases in which we have not assured ourselves, by 

 trial, that the necessary collocation of causes, what- 

 ever it may be, exists. It is to this class of laws 

 alone that the property, which philosophers usually 

 consider as characteristic of empirical laws, belongs in 

 all its strictness ; the property of being unfit to be relied 

 on beyond the limits of time, place, and circumstance, 

 in which the observations have been made. These are 

 empirical laws in a more emphatic sense ; and when I 

 employ that term (except where the context mani- 

 festly indicates the reverse) I shall generally mean to 

 designate those uniformities only, whether of succes- 

 sion or of coexistence, which are not known to be 

 laws of causation. 



