362 THE REAL WORLD 



But now, if a thing is nothing but a "thought-symbol," how does it 

 happen that there is a "compound sensation of relative fixedness"? 

 One cannot very well dismiss it, as an incidental product of hu- 

 man sensory equipment or human usage of certain "cultural posits," 

 without at once invalidating the tacit assumption that "sensations" 

 are given. But in any case, recalling the evidence noted in Chapter I, 

 what about those sensations allegedly given as the physical object is 

 not? If human inference is involved in conception of the thing, is it 

 not at least as deeply involved in conception of the hypothetically 

 pure "sensation"— then also a mere "thought-symbol"? 



Illogical cynicism. The atheist can no more demonstrate the non- 

 existence of gods than the believer can demonstrate their existence. 

 Though probably no weaker, the logical position of the former is 

 surely no stronger than that of the latter. The naive realist insists that 

 physical objects "really exist." Mach asserts that all such physical 

 constructs are "convenient fictions." Convenient they surely are but, 

 just as the naive realist is impotent to demonstrate their existence, 

 Mach is impotent to show them fictional by arguing that: 



... in the investigation of nature, we have to deal only with knowl- 

 edge of the connexion of appearances with one another. What we 

 represent to ourselves behind the appearances exists only in our un- 

 derstanding, . . . 



Because "what we represent to ourselves behind the appearances" 

 efficiently discharges a correlative function, therefore the hypotheti- 

 cal elements exist only in our understanding? Nietzsche comments : 



Parmenides said: "One can form no concept of the nonexistent";— 

 we are at the other extreme, and say, "That of which a concept can 

 be formed, is certainly fictional." 



Positivist arguments bristle with this kind of non sequitur. Our 

 laws and theories contain a substantial human element, and can give 

 us no perfectly objective representation of the world. Therefore they 

 tell us nothing of the world. Quantum mechanics presents a major 

 challenge to human understanding. Therefore human understanding 

 is impossible. Schrodinger speaks bitterly of the "Neo-Machians in 

 present-day quantum mechanics." 



Some people believe they have in Mach's principle found a wonder- 

 ful way out of this dilemma [i.e., the wave-particle dualism] which 



