20 THE AIM AND ACHIEVEMENTS OF SCIENTIFIC METHOD. 



able from the latter. This leaves outstanding the difficulty 

 that two really different objects are not always distinguished ; 

 a difficulty which, though it has quite rightly been indicated* 

 as a serious one for Realist philosophies of this type, is one 

 which in a treatment that aims at little more than indicating 

 clearly the philosophical basis adopted in this essay, I may 

 perhaps ask leave to hope is not insuperable while we 

 pass on. 



' - ' 7. ' - 



When we turn from the world of physical existences we 

 find the^ plain man^\ applying with -less confidence -the distinc-' 

 tions which are clear and easy throughout at least the greater 

 part of the material realm. Interest in psychical existences 

 arose long after language, "under the influence of interest' in the 

 material environment, had developed its permanent essential 

 forms. When attention became directed' towards objects of a 

 fundamentally different character the existing machinery of 

 expression was utilised, with as little modification as possible, 

 to deal ;with them. The result is that it is difficult to 

 determine in the case of " things " which are not undoubted 

 substantive material unities, how far the use of the term is 

 simply conventional, implying no more than a possible 

 "subject of discourse." Thus when the poet says of sleep 



that 



" it is a blessed tKing 

 Beloved from pole to pole," 



it seems evident that the word is used conventionally beyond 

 the original limits of its application, just as in algebra the 

 notion of indices, which, in the original definition, must be 

 integers, is modified to include fractional and negative numbers. 

 How far the same thing would be regarded by the plain man 

 as true in the case of psychical existences, thoughts, feelings, 

 and the like, it would be hard to determine. Since, however, 



* See Mind, N.S., No. 58, p. 231. 



