SECT. 31.] Fallacies. 363 



stances of Inductive and Analogical extension it is perfectly 

 harmless. 



30. A familiar example will serve to bring out the 

 three different possible conclusions mentioned above. We 

 have observed it rain on ten successive days. A and B con 

 clude respectively for and against rain on the eleventh day ; 

 C maintains that the past rain affords no data whatever for 

 an opinion. Which is right ? We really cannot determine 

 a priori. An appeal must be made to direct observation, or 

 means must be found for deciding on independent grounds 

 to which class we are to refer the instance. If, for example, 

 it were known that every country produces its own rain, we 

 should choose the third rule, for it would be a case of drawing 

 from a limited supply. If again we had reasons to believe 

 that the rain for our country might be produced anywhere 

 on the globe, we should probably conclude that the past 

 rainfall threw no light whatever on the prospect of a con 

 tinuance of wet weather, and therefore take the second. 

 Or if, finally, we knew that rain came in long spells or sea 

 sons, as in the tropics, then the occurrence of ten wet days 

 in succession would make us believe that we had entered on 

 one of these seasons, and that therefore the next day would 

 probably resemble the preceding ten. 



Since then all these forms of such an Inductive rule are 

 possible, and we have often no a priori grounds for preferring 

 one to another, it would seem to be unreasonable to attempt 

 to establish any universal formula of anticipation. All that 

 we can do is to ascertain what are the circumstances under 

 which one or other of these rules is, as a matter of fact, 

 found to be applicable, and to make use of it under those 

 circumstances. 



31. (VII.) In the cases discussed in (V.) the almost 

 infinitely small chances with which we were concerned were 



