EXTENSION OF LAWS TO ADJACENT CASES. 79 



by night. On the sun's own surface, for instance, this may 

 be the case. 



Finally, even when the derivative uniformity is itself a law 

 of causation (resulting from the combination of several causes), 

 it is not altogether independent of collocations. If a cause 

 supervenes, capable of wholly or partially counteracting the 

 effect of any one of the conjoined causes, the effect will no 

 longer conform to the derivative law. While, therefore, each 

 ultimate law is only liable to frustration from one set of 

 counteracting causes, the derivative law is liable to it from 

 several. Now, the possibility of the occurrence of coun- 

 teracting causes which do not arise from any of the conditions 

 involved in the law itself, depends on the original colloca- 

 tions. 



It is true that (as we formerly remarked) laws of causation, 

 whether ultimate or derivative, are, in most cases, fulfilled 

 even when counteracted ; the cause produces its effect, though 

 that effect is destroyed by something else. That the effect 

 may be frustrated, is, therefore, no objection to the universality 

 of laws of causation. But it is fatal to the universality 

 of the sequences or coexistences of effects, which compose 

 the greater part of the derivative laws flowing from laws of 

 causation. When, from the law of a certain combination of 

 causes, there results a certain order in the effects ; as from 

 the combination of a single sun with the rotation of an opaque 

 body round its axis, there results, on the whole surface of 

 that opaque body, an alternation of day and night ; then if 

 we suppose one of the combined causes counteracted, the 

 rotation stopped, the sun extinguished, or a second sun super- 

 added, the truth of that particular law of causation is in no 

 way affected ; it is still true that one sun shining on an 

 opaque revolving body will alternately produce day and night ; 

 but since the sun no longer does shine oh such a body, the 

 derivative uniformity, the succession of day and night on 

 the given planet, is no longer true. Those derivative uni- 

 formities, therefore, which are not laws of causation, are 

 (except in the rare case of their depending on one cause 

 alone, not on a combination of causes,) always more or less 



