SECT. 16.] Induction. 217 



interests of truth and consistency prevent them therefore 

 from contradicting one another. As isolated propositions 

 it might have been the case that all men live to fifty, and 

 that no Indian residents do so, but having recognised that 

 some men are residents in India, we see at once that these 

 premises are inconsistent, and therefore that one or other 

 of them must be rejected. In all applied logic this necessity 

 of avoiding self-contradiction is so obvious and imperious 

 that no one would think it necessary to lay down the formal 

 postulate that all such possible major premises are to be 

 mutually consistent. To suppose that this postulate is not 

 complied with, would be in effect to make two or more con 

 tradictory assumptions about matters of fact. 



16. But now observe the difference when we attempt 

 to take the corresponding step in Probability. For ordinary 

 propositions, universal or particular, substitute statistical 

 propositions of what we have been in the habit of calling 

 the proportional kind. In other words, instead of asking 

 whether the man will live for twenty years, let us ask whether 

 he will live for one year ? We shall be unable to find any 

 universal propositions which will cover the case, but we may 

 without difficulty obtain an abundance of appropriate pro 

 portional ones. They will be of the following description : 

 Of men aged 30, 98 in 100 live another year; of residents in 

 India a smaller proportion survive, let us for example say 

 90 in 100 ; of men suffering from cancer a smaller proportion 

 still, let us say 20 in 100. 



Now in both of the respects to which attention has just 

 been drawn, propositions of this kind offer a marked con 

 trast with those last considered. In the first place, they do 

 not, like ordinary propositions, either assert unequivocally 

 yes or no, or else refuse to open their lips ; but they give 

 instead a sort of qualified or hesitating answer concerning 



