28 WHAT IS SCIENCE? 



concerning which there is agreement ; it is something 

 which we infer from such sensations and judgments. 

 And this inference may be wrong. As has been said, 

 nobody maintains that it is entirely wrong, but it is very 

 strongly held in some quarters that some parts of the 

 inference usually made by common sense are wrong and 

 seriously misleading. If we call science the study of 

 nature, we are bound to admit that, if the common-sense 

 view about nature is largely mistaken, there must also 

 be a considerable element of doubt as to the real value 

 of the conclusions of science itself ; in other words, 

 science must to some extent be subordinated to philosophy, 

 in whose province lies the business of deciding the 

 worth of the popular conception of nature. Against such 

 subordination students of science have always protested : 

 and they can maintain their protest if they adopt the view 

 that science studies, not the external world, but merely 

 those judgments on which common sense, rightly or 

 wrongly, bases its belief in an external world. And it 

 may here be noted that among the difficulties that are 

 avoided by the definition are those to which reference 

 was made on p. 23. 



But there is a much more important difference. It is 

 true that the popular belief in the external world is 

 founded primarily upon the fact of agreement about 

 sensations ; but, in deciding what part of our experience 

 is to be referred to that external world, common sense 

 does not adhere at all strictly to the criterion on which 

 that belief is ultimately based. We do not ordinarily 

 refuse to regard as part of the external world everything 

 about which there is not universal agreement. A very 

 simple example will illustrate this point. A moment 

 ago a book fell from my table to the floor : I heard a sound 

 and, 'looking round, saw the book on the floor. Now I 

 had no hesitation in referring that experience to some- 

 thing happening in the external world ; but there was 



