80 INDUCTION. 



contingent on collocations ; and are hence subject 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 

 \vithin the conditions of time and place confirmed by actual 

 observation. 



2. This principle, when stated in general terms, seems 

 clear and indisputable; yet many of the ordinary judgments 

 of mankind, the propriety of which is not questioned, have at 

 least the semblance of being inconsistent 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 years past, but they do not include the 

 future. Yet we infer with confidence that the sun will 

 rise to-morrow ; and nobody doubts that we are entitled 

 to do so. Let us consider what is the warrant for this 

 confidence. 



In the example in question, we know the causes on which 

 the derivative uniformity depends. They are, the sun giving 

 out light, the earth in a state of rotation and intercepting 

 light. The induction which shows these to be the real 

 causes, and not merely prior effects of a common cause, being 

 complete ; the only circumstances which could defeat the 

 derivative law are such as would destroy or counteract one 

 or other of the combined causes. While the causes exist, 

 and are not counteracted, the effect will continue. If they 

 exist and are not counteracted to-morrow, the sun will rise 

 to-morrow. 



Since the causes, namely the sun and the earth, the one in 

 the state of giving out light, the other in a state of rotation, 

 will exist until something destroys them ; all depends on 

 the probabilities of their destruction, or of their counter 

 action. We know by observation (omitting the inferential 

 proofs of an existence for thousands of ages anterior), that 

 these phenomena have continued for (say) five thousand years. 

 Within that time there has existed no cause sufficient to 



