224 INTRODUCTION TO PHILOSOPHY OF SCIENCE 



to verify his imaginative efforts by returning to the realm 

 of data from which he departed in search of explanatory 

 conceptions. 



It should be clear that the heart of this act lies in percep- 

 tion, which is, as was suggested in Chapter V, the essential 

 method for getting events. All that was said in that con- 

 nection may be repeated here, with a slight shift in empha- 

 sis. Whereas perception in the context of the movement 

 of discovery is aimed at the derivation of symbols, percep- 

 tion in the context of the movement of verification is aimed 

 at the verification of symbols. One perceives not merely 

 to get ideas but to establish conjectures. The significant 

 difference in the perceptual act in the two cases lies in the 

 greater emphasis on control in the latter case. In the 

 former, one observes anywhere and at any time for the 

 purpose of noting anything that might occur; in the latter, 

 one observes a specific spatio-temporal situation for the 

 purpose of noting whether a specific event occurs. There is, 

 consequently, in the latter case, a definite psychological 

 framework within which the perceptual act takes place; 

 attention becomes keener because of the functioning of the 

 psychological operators. But there is a corresponding prone- 

 ness to error, since the mind tends to read preconceived 

 ideas into the physical situation. Bacon was so conscious 

 of this fact that he placed undue emphasis on the movement 

 of discovery, hoping by this to eliminate the verificatory 

 act. It seems futile to argue whether facts precede hy- 

 potheses or hypotheses precede facts. Certainly at the stage 

 in which science emerges upon the scene both facts and 

 hypotheses are given. It is quite unlikely that a pure fact, 

 without an increment of interpretative material, is ever 

 perceived; and it is equally unlikely that a pure hypothesis, 

 without connection with any observed fact, is ever conceived. 

 Mind is not a tabula rasa, as Locke supposed, nor does it 

 approach the world with a bundle of fixed forms into which 

 facts are to be fitted, as Plato suggested. All that need 

 be recognized for science is that investigation into nature 



