SCIENTIFIC METHOD IN PHILOSOPHY ^23 



in this case there will be a causal law according to which 

 objects of perception are not independent of being 

 perceived. But even if this be the case, it may never- 

 theless also happen that there are purely physical causal 

 laws determining the occurrence of objects which are 

 perceived by means of other objects which perhaps are 

 not perceived. In that case, in regard to such causal 

 laws objects of perception will be independent of being 

 perceived. Thus the question whether objects of per- 

 ception are independent of being perceived is, as it 

 stands, indeterminate, and the answer will be yes or no 

 according to the method adopted of making it determinate. 

 I believe that this confusion has borne a very large part 

 in prolonging the controversies on this subject, which 

 might well have seemed capable of remaining for ever 

 undecided. The view which I should wish to advocate 

 is that objects of perception do not persist unchanged 

 at times when they are not perceived, although probably 

 objects more or less resembling them do exist at such 

 times ; that objects of perception are part, and the only 

 empirically knowable part, of the actual subject-matter of 

 physics, and are themselves properly to be called physical ; 

 that purely physical laws exist determining the character 

 and duration of objects of perception without any 

 reference to the fact that they are perceived ; and that 

 in the establishment of such laws the propositions of 

 physics do not presuppose any propositions of psychology 

 or even the existence of mind. I do not know whether 

 realists would recognise such a view as realism. All 

 that I should claim for it is, that it avoids difficulties 

 which seem to me to beset both realism and idealism as 

 hitherto advocated, and that it avoids the appeal which 

 they have made to ideas which logical analysis shows 

 to be ambiguous. A further defence and elaboration of 



