34 WHAT IS SCIENCE? 



To make this important matter clear, it may be well 



to suggest a procedure which might be adopted. We 



might make both the normal and the abnormal people 



look at the objects through a red glass. Through the 



glass, of course, everything will look the same colour to 



both normal and abnormal, but different objects will 



appear different shades of the same colour. The pink 



objects A, B, C, . . . will all appear the same shade, 



and so will the greenish objects X, Y, Z . . . ; but the 



former will appear a lighter shade than the latter ; and 



they will appear a lighter shade, not only to the normal 



people, who see the difference of colour when the red 



glass is not interposed, but also to the abnormal, who do 



not see this difference. Here then universal agreement 



has been attained ; every one agrees that through the 



red glass the objects look different. Accordingly we 



regard the appearance through the red glass as a better 



basis for science than the appearance without the red 



glass ; we say that scientifically the objects are different 



in colour if they appear different through the red glass, 



and we call one set of people normal and the other 



abnormal because one set agree and the other do not 



with the distinction based on this truly scientific criterion. 



It is a very remarkable fact that, wherever we find 



such abnormal people under permanent hallucinations 



(and we find them in regard to all the senses), we can 



always find another test which, in the manner just 



described, enables us to restore universal agreement. It 



is this fact, which could not be anticipated, which makes 



science possible, and gives its great importance to the 



test of universal agreement. 



But perhaps the reader may doubt whether there are 

 really judgments about which every one agrees, if we are 

 allowed to include people with the most extremely 

 abnormal sensations, such as the totally blind or the 

 totally deaf. The doubt can only be removed by quoting 



