PHILOSOPHICAL SOCIETY OF WASHINGTON. 45 



there is one general feature of its method which is of fundamental 

 significance. It is that every term which it uses and every propo- 

 sition which it enunciates has a precise meaning which can be 

 made evident by proper definitions. This general principle of 

 scientific language is much more easily inculcated by example than 

 subject to exact description ; but I shall ask leave to add one to 

 several attempts I have made to define it. If I should say that 

 when a statement is made in the language of science the speaker 

 knows what he means, and the hearer either knows it or can be 

 made to know it by proper definitions, and that this community of 

 understanding is frequently not reached in other departments of 

 thought, I might be understood as casting a slur on whole depart- 

 ments of inquiry. Without intending any such slur, I may still 

 say that language and statements are worthy of the name scientific 

 as they approach this standard ; and, moreover, that a great deal 

 is said and written which does not fulfill the requirement. The 

 fact that words lose their meaning when removed from the connec- 

 tions in which that meaning has been acquired and put to higher 

 uses, is one which, I think, is rarely recognized. There is nothiDg 

 in the history of philosophical inquiry more curious than the fre- 

 quency of interminable disputes on subjects where no agreement 

 can be reached because the opposing parties do not use words in 

 the same sense. That the history of science is not free from this 

 reproach is shown by the fact of the long dispute whether the 

 force of a moving body was proportional to the simple velocity 

 or to its square. Neither of the parties to the dispute thought it 

 worth while to define what they meant by the word " force," and it 

 was at length found that if a definition was agreed upon the seem- 

 ing difference of opinion would vanish. Perhaps the most striking 

 feature of the case, and one peculiar to a scientific dispute, was that 

 the opposing parties did not differ in their solution of a single 

 mechanical problem. I say this is curious, because the very fact 

 of their agreeing upon every concrete question which could have 

 been presented, ought to have made it clear that some fallacy was 

 lacking in the discussion as to the measure of force. The good 

 effect of a scientific spirit is shown by the fact that this discussion 

 is almost unique in the history of science during the past two centu- 

 ries, and that scientific men themselves were able to see the fallacy 

 involved, and thus to bring the matter to a conclusion. 



If we now turn to the discussions of philosophers, we shall find at 



