126 Measurement of Belief. [CHAP. vi. 



feelings are, of course, exceptional, but we should neverthe 

 less find that the emotional element, in some form or other, 

 makes itself felt on almost every occasion. It is very seldom 

 that we cannot speak of our surprise or expectation in refer 

 ence to any particular event. Both of these expressions, but 

 especially the former, seem to point to something more than 

 mere belief. It is true that the word expectation is gene 

 rally defined in treatises on Probability as equivalent to 

 belief; but it seems doubtful whether any one who attends 

 to the popular use of the terms would admit that they were 

 exactly synonymous. Be this however as it may, the emo 

 tional element is present upon almost every occasion, and its 

 disturbing influence therefore is constantly at work. 



8. Another cause, which co-operates with the former, 

 is to be found in the extreme complexity and variety of the 

 evidence on which our belief of any proposition depends. 

 Hence it results that our actual belief at any given moment 

 is one of the most fugitive and variable things possible, so 

 that we can scarcely ever get sufficiently clear hold of it to 

 measure it. This is not confined to the times when our 

 minds are in a turmoil of excitement through hope or fear. 

 In our calmest moments we shall find it no easy thing to 

 give a precise answer to the question, How firmly do I hold 

 this or that belief? There may be one or two prominent 

 arguments in its favour, and one or two corresponding ob 

 jections against it, but this is far from comprising all the 

 causes by which our state of belief is produced. Because 

 such reasons as these are all that can be practically intro 

 duced into oral or written controversies, we must not con 

 clude that it is by these only that our conviction is influenced. 

 On the contrary, our conviction generally rests upon a sort 

 of chaotic basis composed of an infinite number of inferences 

 and analogies of every description, and these moreover dis- 



