EXTENSION OF LAWS TO ADJACENT CASES, 389 



cause itself. If a and h accompany or succeed one another as effects of the 

 cause A, it by no means follows that A is the only cause which can pro- 

 duce them, or that if there be another cause, as B, capable of producing «, 

 it must produce b likewise. The conjunction, therefore, of a and b perhaps 

 does not hold universally, but only in the instances in which a arises from 

 A. When it is produced by a cause other than A, a and b may be dissev- 

 ered. Day (for example) is always in our experience followed by night; 

 but day is not the cause of night; both are successive effects of a common 

 cause, the periodical passage of the spectator into and out of the earth's 

 shadow, consequent on the eai'th's rotation, and on the illuminating prop- 

 erty of the sun. If, therefore, day is ever produced by a different cause 

 or set of causes from this, day will not, or at least may not, be followed 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 in- 

 dependent of collocations. If a cause supervenes, capable of wholly or par- 

 tially counteracting the effect of any one of the conjoined causes, the effect 

 will no longer conform to the derivative law. While, therefore, each ulti- 

 mate 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 counteracting causes which do not arise from any of the con- 

 ditions involved in the law itself depends on the original collocations. 



It is true that, as we formerly remarked, laws of causation, whether ulti- 

 mate 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 co-existences of effects, which compose the gi-eater 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 com- 

 bined causes counteracted, the rotation stopped, the sun extinguished, or a 

 second sun superadded, the truth of that particular law of causation is in 

 no way affected ; it is still true that one sun shining on an opaque revolv- 

 ing body will alternately produce day and night; but since the sun no 

 longer does shine on such a body, the derivative uniformity, the succession 

 of day and night on the given planet, is no longer true. Those derivative 

 uniformities, 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 contingent on collocations ; and are hence sub- 

 ject to the characteristic infirmity of empirical laws — that of being admis- 

 sible only where the collocations are known by experience to be such as 

 are requisite for the truth of the law; that is, only within the conditions 

 of time and place confirmed by actual observation. 



§ 2. This principle, when stated in general terms, seems clear and indis- 

 putable ; yet many of the ordinary judgments of mankind, the propriety 

 of which is not questioned, have at least the semblance of being inconsist- 

 ent with it. On what grounds, it may be asked, do we expect that the 

 sun will rise to-morrow ? To-morrow is beyond the limits of time compre- 

 hended in our observations. They have extended over some thousands of 



