72 SCIENTIFIC METHOD IN PHILOSOPHY 



data, with a view to discovering what sort of world can be 

 constructed by their means alone. 



Our data now are primarily the facts of sense (i.e. of 

 our own sense-data) and the laws of logic. But even the 

 severest scrutiny will allow some additions to this slender 

 stock. Some facts of memory especially of recent 

 memory seem to have the highest degree of certainty. 

 Some introspective facts are as certain as any facts of 

 sense. And facts of sense themselves must, for our 

 present purposes, be interpreted with a certain latitude. 

 Spatial and temporal relations must sometimes be included, 

 for example in the case of a swift motion falling wholly 

 within the specious present. And some facts of com- 

 parison, such as the likeness or unlikeness of two shades 

 of colour, are certainly to be included among hard data. 

 Also we must remember that the distinction of hard and 

 soft data is psychological and subjective, so that, if there 

 are other minds than our own which at our present 

 stage must be held doubtful the catalogue of hard data 

 may be different for them from what it is for us. 



Certain common beliefs are undoubtedly excluded 

 from hard data. Such is the belief which led us to 

 introduce the distinction, namely, that sensible objects 

 in general persist when we are not perceiving them. 

 Such also is the belief in other people's minds : this belief 

 is obviously derivative from our perception of their 

 bodies, and is felt to demand logical justification as soon 

 as we become aware of its derivativeness. Belief in 

 what is reported by the testimony of others, including 

 all that we learn from books, is of course involved in the 

 doubt as to whether other people have minds at all. 

 Thus the world from which our reconstruction is to 

 begin is very fragmentary. The best we can say for it 

 is that it is slightly more extensive than the world at 



