THE EVOLUTION OF SCIENTIFIC THEORIES 289 



hierarchic series of more and more abstract theories acquires its 

 physical relevance only as a member of an unbroken series. The de- 

 mand for correspondence safeguards the integrity of that series. And 

 the chronological succession of "revolutionary" advances in scientific 

 theory is, thereby, fashioned into the risers of the perfectly contin- 

 uous logical stairway by which alone we can descend from our 'Tiigh- 

 est" theory to the ground level of experience. 



However long we may choose to discourse on the intangible en- 

 tities of quantum mechanics, a science of quantum mechanics must 

 ultimately be brought to bear in the mode Oppenheimer describes. 



The measurements that we have talked about in such highly abstract 

 form do in fact come down in the end to looking at the position of a 

 pointer, or the reading of time on a watch, or measuring out where on 

 a photographic plate or a phosphorescent screen a flash of light or a 

 patch of darkness occurs. They all rest on reducing the experience 

 with atomic systems to experiment and observation made manifest, 

 unambiguous, and objective in the behavior of large objects, where 

 the precautions and incertitudes of the atomic domain no longer di- 

 rectly apply. 



To these large objects we of course apply the concepts of classical 

 physics and, as Heisenberg maintains, this application is forced 

 on us. 



The use of these concepts, including space, time and causality, is in 

 fact the condition for observing atomic events and is, in this sense of 

 the word, "a priori." What Kant had not foreseen was that these a 

 priori concepts can be the conditions for science and at the same time 

 can have only a limited range of applicability. When we make an ex- 

 periment we have to assume a causal chain of events that leads from 

 the atomic event through the apparatus finally to the eye of the ob- 

 sei-ver; if this causal chain was not assumed, nothing could be known 

 about the atomic event. 



There is an important point here. The older physics is not simply 

 contained inside the new; the older physics continues, with undimin- 

 ished competence, to function independently beside the new. 



NOT FALSIFICATION BUT SUBORDINATION 



When a new form of life appears in nature, it need not wholly dis- 

 place the parental form(s). The emergence of amphibians substan- 



