SECT. 7.] Measurement of Belief. 125 



the belief side of the question the prominence given to it by 

 De Morgan and others, certainly before the science could be 

 defined from that side, it would be necessary, it appears, to 

 establish the two following positions, against both of which 

 strong objections can be brought. 



(1) That our belief of every proposition is a thing which 

 we can, strictly speaking, be said to measure ; that 

 there must be a certain amount of it in every case, 

 which we can realize somehow in consciousness and 

 refer to some standard so as to pronounce upon its 

 value. 



(2) That the value thus apprehended is the correct one 

 according to the theory, viz. that it is the exact 

 fraction of full conviction that it should be. This 

 statement will perhaps seem somewhat obscure at 

 first ; it will be explained presently. 



7. (I) Now, in the first place, as regards the difficulty 

 of obtaining any measure of the amount of our belief. One 

 source of this difficulty is too obvious to have escaped notice ; 

 this is the disturbing influence produced on the quantity of 

 belief by any strong emotion or passion. A deep interest in 

 the matter at stake, whether it excite hope or fear, plays great 

 havoc with the belief-meter, so that we must assume the 

 mind to be quite unimpassioned in weighing the evidence. 

 This is noticed and acknowledged by Laplace and others; 

 but these writers seem to me to assume it to be the only 

 source of error, and also to be of comparative unimportance. 

 Even if it were the only source of error I cannot see that it 

 would be unimportant. We experience hope or fear in so 

 very many instances, that to omit such influences from con 

 sideration would be almost equivalent to saying that whilst 

 we profess to consider the whole quantity of our belief we 

 will in reality consider only a portion of it. Very strong 



