CHAPTER V 



PERCEPTION 



Now that the tools of science have been considered, the 

 way is prepared for an examination of the methods and 

 techniques by means of which science attains its end. The 

 task of science, as has been shown, consists in the examina- 

 tion of the realm of events and in the discovery or invention 

 of a system of symbols having as its main function the 

 portrayal of the essential features of that realm. How does 

 science set about this job? 



THE STARTING-POINT OF SCIENCE 



It may seem a commonplace to assert that science must 

 begin with the realm of events. Events are fixed and ob- 

 jective, and constitute both the origin of knowledge and 

 the point to which reference must be made in case verification 

 is desired. Knowledge, on the other hand, is flexible and must 

 be molded to suit the events which it is presumed to portray. 

 If the scientist describes nature he must start with nature. 



On closer examination, however, the statement proves 

 to be not so obvious; in fact it may not even be true. Sci- 

 ence starts not with nature, but with a selection from na- 

 ture, and the particular selection is determined, presumably, 

 by the idea in the mind of the scientist at the moment. 

 The scientist does not respond to all events equally; on the 

 contrary, he attends to those which are relevant either 

 positively or negatively to a theory which he is debating 

 and seeking to verify. In fact, since attention is a selective 

 response, one may well ask whether there would be any data 

 at all were it not for specific interests. When one walks 

 down a busy street deeply immersed in thought, it is fair 

 to say that the busy scenes do not exist for him; and if he 

 does react he does so selectively, and, as a consequence, 



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