ANALYSIS OF SCIENTIFIC CONCEPTS 249 



now most familiar to us. 1 Hence we may find that the 

 techniques should be called logically rather than psycho- 

 logically elucidating. From this point of view there is rel- 

 evance in the following quotation from D'Alembert: 2 

 "The most abstract notions, such as the majority of man- 

 kind regard as the most inaccessible, are often those which 

 carry with them the greatest elucidating power: our ideas 

 seem to be blotted out by obscurity in proportion as, in 

 any object, we examine into its sensible properties." Unless 

 the distinction between logical and psychological elucidation 

 is kept in mind, this quotation is in essential conflict with 

 remarks made in connection with the problem of the empir- 

 ical foundation. Abstract ideas are logically clear but em- 

 pirically obscure; sense-data, on the other hand, are em- 

 pirically clear but logically obscure. 



Finally, the clarification of the basic concepts and assump- 

 tions of science cannot possibly be made through the method 

 of pointing. Here the difficulty is not merely a matter of the 

 ambiguity in the denotative gesture, but a matter of the 

 inherent elusiveness of the entities in question. In fact 

 many scientists, as has already been seen, give to all such 

 entities a fictional status and refuse to find a place for them 

 in nature. They are essentially mental creations, and have 

 either no connection at all with the empirical realm or else 

 are so remotely related that it is absurd to look for their 

 empirical counterparts. One should not look for an infinitely 

 extended time in nature any more than he should look for a 

 perfect lever. Abstract space, number, order, and the like 

 are not natural entities but conceptual schemes for the 

 interpretation of nature, almost identical with the Kantian 

 forms of perception and understanding. While not all 

 scientists would go to this length in removing abstractions 

 from the realm of the given, most would agree that if such 

 entities do exist they must do so in a manner which is quite 

 different from that of ordinary events. Consequently they 



1 Scientific Thought, p. 26. 



2 Quoted by T. Ribot, Evolution of General Ideas (Chicago: Open Court, 1899), 

 p. 201. 



