202 THE PRINCIPLES OF SCIENCE 



the attempt to look for a strictly causal and dynamic law behind every 

 statistical law. 



If science is genuinely transformed in microphysics, Planck's histori- 

 cal precedents will not compel us to join him in resisting the alleged 

 ultimacy of statistical laws. But a recent statement of de Broglie's 

 suggests that, even yet, there may be some substance to Planck's 

 misgivings. 



For a quarter of a century the purely probabilistic interpretation of 

 wave mechanics has certainly been of service to physicists because it 

 has kept them from being overwhelmed by the study of very arduous 

 problems . . . and thus has permitted them to advance steadily in 

 the direction of applications, which have been numerous and fruitful. 

 But today the heuristic power of wave mechanics, as it is taught, 

 seems in large measure weakened. Everyone recognizes this . . . 



However this may be ( for "everyone" does not "recognize this" ) , the 

 widely alleged ultimacy of the statistical view lies open to attack on 

 what seems to me a far more fundamental plane. The target then is 

 not the statistical view as such, but the more vulnerable pretension 

 to knowledge of a final principle. 



Quantum mechanics produces appreciable changes in our con- 

 ceptions of determinism and causality. But precisely because these 

 are not the first such changes, we may well doubt they are the last. 

 In the general context of his beliefs, the man of the Dark Ages could 

 demonstrate convincingly the absolute unpredictability of the ap- 

 pearance of comets— divinely sent portents of disaster. In much the 

 same way, within the context of early 19th-century science, one could 

 produce an apparently conclusive demonstration that the construc- 

 tion of heavier-than-air flying machines was impossible. Yet behold, 

 we are borne upon the air and we foretell the coming of comets. 

 Presuming the finality of the context of modern quantum mechanics, 

 one can prove the ultimacy of statistical laws, the irreducibility of 

 the wave-particle dualism, and I know not what else. But Bohm cor- 

 rectly emphasizes that the crucial initial presumption is neither dem- 

 onstrated nor demonstrable. 



. . . conclusions have been drawn concerning the need to renounce 

 causality, continuity, and the objective reality of individual micro- 

 objects, which follow neither from the experimental facts underlying 

 the quantum mechanics nor from the mathematical equations in terms 



