OPINION AND PROBABILITY 261 



formity : conformity is not divisible. When, therefore, a judgment 

 or proposition is spoken of as &quot; more or less true,&quot; we must bear 

 in mind the correct meaning of such language : that there is in 

 the judgment a true sense and a false one, that these can be dis 

 tinguished or separated, that this part is true and that false, and 

 that the original composite judgment, in which the unanalysed, 

 or insufficiently analysed, concepts and judgments were united 

 into one mental relation between subject and predicate, wasfatse, 

 taken as a whole, putting the mind that formulated it out of har 

 mony with reality (248). 



Opinion, therefore, is the result of objective evidence which 

 is not grasped or comprehended subjectively with sufficient clear 

 ness to guarantee a certain assent. If objective evidence, which is 

 really sufficient for moral certitude, is grasped with sufficient 

 clearness, but is undervalued, underestimated by the mind that 

 receives it, it will not actually exclude the fear of error from such 

 a mind, though it would from a normal mind. The subjective 

 element is thus seen to be a factor in determining those varying 

 grades of assent ; but logic deals only with the objective element, 

 and its effect upon the normal mind, leaving the study of the sub 

 jective factors to psychology. 



Neither can logic furnish any calculus for determining the 

 precise degree of mental assent proportionate to a given weight 

 of probable reasons. Mental assent is a vital, conscious act, 

 entirely beyond the scope of measurement in terms of any 

 mechanical or quantitative units. It is the objective factors, 

 which constitute the &quot;probable evidence,&quot; that are alone in any 

 way amenable to what has been called the &quot; Logic of Chance &quot; or 

 the &quot; Logic of Probability &quot; (264). The degree of assent with which 

 the individual will respond to probable evidence, and allow the 

 latter to influence his actions and shape his conduct, is a matter of 

 personal prudence and discretion. 



Probable evidence, as we saw, may vary in strength from the 

 extremely vague and doubtful indications that give rise to a mere 

 suspicion, to the very solid and substantial motives that produce 

 the sort of assent described in common language as &quot; moral 

 certitude .&quot; Hence, as there are degrees in the positive firmness 

 of a certain assent, so there are also degrees in that of a probable 

 one. The question may therefore be asked : Can opinion pass 

 gradually into certitude, a probable judgment into a judgment 

 certainly true, a probability into a certainty? Or, the question 



