SECT. 24.] Measurement of Belief. 147 



starting-point ; but we are not bound to inquire whether in 

 every case in which persons have, or claim to have, a certain 

 measure of belief there must be such a series to which to 

 refer it, and by which to justify it. Those who start from 

 the subjective side, and regard Probability as the science of 

 quantitative belief, are obliged to do this, but we are free 

 from the obligation. 



Still the question is one which is so naturally raised in 

 connection with this subject, that it cannot be altogether 

 passed by. I think that to a considerable extent such a 

 justification as that mentioned above will be found applicable 

 in other cases. The fact is that we are very seldom called 

 iipon to decide and act upon a single contingency which can 

 not be viewed as being one of a series. Experience intro 

 duces us, it must be remembered, not merely to a succession 

 of events neatly arranged in a single series (as we have 

 hitherto assumed them to be for the purpose of illustration), 

 but to an infinite number belonging to a vast variety of 

 different series. A man is obliged to be acting, and there 

 fore exercising his belief about one thing or another, almost 

 the whole of every day of his life. Any one person will have 

 to decide in his time about a multitude of events, each one 

 of which may never recur again within his own experience. 

 But by the very fact of there being a multitude, though they 

 are all of different kinds, we shall still find that order is 

 maintained, and so a course of conduct can be justified. In 

 a plantation of trees we should find that there is order of a 

 certain kind if we measure them in any one direction, the 

 trees being on an average about the same distance from each 

 other. But a somewhat similar order would be found if we 

 were to examine them in any other direction whatsoever. So 

 in nature generally; there is regularity in a succession of 

 events of the same kind. But there may also be regularity 



102 



