42 INTRODUCTION TO PHILOSOPHY OF SCIENCE 



technique can be justified? Must his assumptions about 

 method be temporally prior to the use of that method? I 

 think the answer to this question is an unequivocal negative. 

 Certainly most scientists do not make such critiques prior 

 to engaging in their more specifically scientific pursuits. If 

 there are certain assumptions which antedate the procedure 

 of science, these are usually held implicitly rather than 

 explicitly and are correspondingly vague. Probably every 

 scientist believes with greater or less conviction that there 

 is a world which is in some sense external to him, and that 

 in his knowing activities he somehow gets into contact 

 with the world. But these are not held as conscious assump- 

 tions, and it would probably be difficult for the average 

 scientist to show in just what sense they justify his pro- 

 cedure. On the other hand it seems safe to say that there is 

 probably some set of postulates which would justify his 

 procedure, though the scientist may not know what that 

 set is. It may or may not correspond with the vague assump- 

 tions which he held prior to his use of the method, but cer- 

 tainly it need not be formulated anterior to the use of the 

 technique. However, it does seem true that in the long run 

 the scientist would be better off if he were aware of this 

 postulate scheme; hence it is important in this sense for 

 him to know what the logical structure of science is. He is 

 almost certain to find sooner or later that his knowledge is 

 the effect of his method in ways which he had not suspected, 

 and he will probably come upon situations in which his 

 method will prove inadequate. In both types of situation 

 he would be better able to overcome the difficulties if he 

 had an adequate theory of the structure of science. 



This difference between temporal and logical priority 

 creates a difficulty in the treatment of problems of the logic 

 of science. In any question which refers to the logical foun- 

 dations of science one is confronted with the alternative of 

 considering these so-called foundations as they are held 

 implicitly by the scientist prior to his investigation, or as 

 they should be formulated from the point of view of a strictly 



