SCIENCE AND NATURE 10 



a world, why do I regard another class as giving such 

 information and evidence ? Is it not at least reasonable 

 to regard all thoughts in the same way, and to dispense 

 altogether with the recognition of an external world as 

 the cause of some of my thoughts ? 



No serious school of thought has seriously maintained 

 the position indicated in these questions. Indeed, to 

 maintain it or to argue about it would be impossible, or 

 extremely foolish, for anyone who believed it. For 

 we shall revert to this point in a moment if there is no 

 reason for believing in an external world, there is no 

 reason in believing that there are other people with 

 whom to argue or against whom to maintain a position. 

 The view that has been based on the contention that 

 sensations are only thoughts, and therefore, like all other 

 thoughts, internal rather than external, is not that 

 sensations give no evidence at all for believing that there 

 is an external world, but only that the information which 

 we derive from our senses about the external world is 

 not so simple and direct as we often imagine, and conse- 

 quently, that our first impressions about the external 

 world may be very far from the truth. However, for 

 our purpose it is necessary to press the more extreme 

 view, and to ask why we distinguish so sharply between 

 sensations and other thoughts, and why we regard the 

 former and not the latter as giving evidence of, and 

 information about, an external world. In pressing the 

 view, I have, of course, no intention of maintaining that 

 our habitual distinction is not valid ; I only want to 

 elicit what is the difference between the two classes of 

 thoughts which makes it valid. Our question is, What 

 is the difference between the thoughts which we call 

 sensations, and connect with our organs of sense, and 

 the thoughts which we call memory, or reasoning, or 

 will ; and why does this difference lead us to refer the 

 first class, but not the second, to an external world ? 



