MOTION, FORCE, MATTER 325 



carrying a heavy valise, lifting ourselves by our arms from 

 a rigid bar, pressing upon a table-top, and so on. These are 

 facts of experience, and anyone with a feeling for reality 

 could hardly deny that they must be reckoned with in any 

 comprehensive scientific theory. Just how they exist is not 

 important. Some writers, for example, insist that forces are 

 resident merely in our muscles, hence do not have a part 

 in the physical world but only in the physiological, or perhaps 

 the psychological, world. Others, Broad for example, insist 

 that we must distinguish between our feeling of strain and 

 the strains which we feel. "Force is not supposed to be 

 our feelings of strain; it is simply supposed that the strains 

 which we feel are forces, or are indications of forces." 1 

 Again, still others may dispute as to whether force is a purely 

 relative aspect of events, depending for its existence upon 

 the presence of the observer, or an objective feature, wholly 

 independent of the observer; for example, is it correct to 

 say that the sun attracts the earth through a force of gravi- 

 tation, or is such a conception meaningless unless one sup- 

 poses that the sun is in some respect like a human observer, 

 and hence is able to feel the force? These are some of the 

 most representative of the alternative views. But whatever 

 status is given to forces, a recognition of their unanalyzable 

 character seems basic. One cannot say what forces are, for 

 to do so would imply the existence of something which is 

 psychologically more basic than they are. To call them 

 "efforts," "resistances," "strains," "tensions," etc., is not 

 to define them but to attempt through alternative designa- 

 tions to point to them. Here, as in the case of all empirical 

 concepts, one's only method of clarification is through deno- 

 tation. 



Furthermore, it seems undeniable that forces exhibit 

 themselves always as attached to events. There are no dis- 

 embodied forces; forces always manifest themselves as 

 properties of things which push, pull, weigh, resist, impel, 

 attract, and press. To say that force always certifies the 



1 Ibid., pp. 162-163. 



