284 REALITY 



study, to describe as fully and accurately as possible, 

 and to discover the laws by which it combines now with 

 one view-point, now with another. This common ele- 

 ment cannot be placed in one man's consciousness 

 rather than in another's; it must be in neutral ground — 

 an external world. 



It is true that I have a strong impression of an external 

 world apart from any communication with other con- 

 scious beings. But apart from such communication 

 I should have no reason to trust the impression. Most 

 of our common impressions of substance, world-wide 

 instants, and so on, have turned out to be illusory, and 

 the externality of the world might be equally untrust- 

 worthy. The impression of externality is equally strong 

 in the world that comes to me in dreams; the dream- 

 world is less rational, but that might be used as an argu- 

 ment in favour of its externality as showing its dissocia- 

 tion from the internal faculty of reason. So long as we 

 have to deal with one consciousness alone, the hypothesis 

 that there is an external world responsible for part of 

 what appears in it is an idle one. All that can be asserted 

 of this external world is a mere duplication of the know- 

 ledge that can be much more confidently asserted of the 

 world appearing in the consciousness. The hypothesis 

 only becomes useful when it is the means of bringing 

 together the worlds of many consciousnesses occupying 

 different view-points. 



The external world of physics is thus a symposium 

 of the worlds presented to different view-points. There 

 is general agreement as to the principles on which the 

 symposium should be formed. Statements made about 

 this external world, if they are unambiguous, must be 

 either true or false. This has often been denied by 

 philosophers. It is quite commonly said that scientific 



