SECT. 15.] Measurement of Belief. 135 



hypothetically ; viz. if the contingencies are exactly alike, 

 then our belief is so apportioned, the question whether the 

 contingencies are equal being of course decided as the ob 

 jective data of Logic or Mathematics are decided. 



To discuss this question fully would require a statement 

 at some length of the reasons in favour of the objective or 

 material view of Logic, as opposed to the Formal or Con- 

 ceptualist. I shall have to speak on this subject in another 

 chapter, and will not therefore enter upon it here. But one 

 conclusive objection which is applicable more peculiarly to 

 Probability may be offered at once. To pursue the line of 

 enquiry just indicated, is, as already remarked, to desert 

 the strictly logical ground, and to take up that appropriate 

 to psychology ; the proper question, in all these cases, being 

 not what do men believe, but what ought they to believe ? 

 Admitting, as was done above, that in the case of Formal 

 Logic these two enquiries, or rather those corresponding to 

 them, practically run into one, owing to the fact that men 

 cannot consciously think wrongly; it cannot be too strongly 

 insisted on that in Probability the two are perfectly sepa 

 rable and distinct. It is of no use saying what men do or 

 will believe, we want to know what they will be right in 

 believing ; and this can never be settled without an appeal 

 to the phenomena themselves. 



15. But apart from the above considerations, this way 

 of putting the case does not seem to me at all conclusive. 

 Take the following example. A man 1 finds himself on the 



1 It is necessary to take an ex- fore there is nothing of the nature 



ample in which the man is forced to of belief to be extracted out of his 



act, or we should not be able to shew mental condition. He very likely 



that he has any belief on the subject would take this ground if we asked 



at all. He may declare that he him, as De Morgan does, with a 



neither knows nor cares anything slightly different reference (Formal 



about the matter, and that there- Logic, p. 183), whether he considers 



