THE TEST OF TRUTH 



plies that the entire intercourse of the mind 

 with the environment is witness in favour of 

 the proposition and against its negation. 



It is indeed a popular misconception,- — a 

 misconception which lies at the bottom of that 

 manner of philosophizing which is called Em- 

 piricism, — that nothing can be known to be 

 true which cannot be demonstrated. To be 

 convinced that this is a misconception, we need 

 but to recollect what a demonstration is. Every 

 demonstration consists, in the first place, of a 

 series of steps in each of which the group of 

 relations expressed in a proposition is included 

 in some other and wider group of relations, — 

 is seen to be like some other group previously 

 constituted. Now if this process of inclusion is 

 not to be carried on forever, we must come at 

 last to some widest group, — to some general- 

 ization which cannot be included in any wider 

 generalization, and of which we can only say that 

 the truth which it expresses is so completely 

 abstracted from perturbing conditions that it 

 can be recognized by a simple act of conscious- 

 ness as self- evident. If, for example, " we 

 ascribe the flow of a river to the same force 

 which causes the fall of a stone," and if, " in 

 further explanation of a movement produced by 

 gravitation in a direction almost horizontal, we 

 cite the law that fluids subject to mechanical 

 forces exert reactive forces which are equal in 

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