198 INTRODUCTION TO PHILOSOPHY OF SCIENCE 



red color, and bright metallic luster can be quite readily 

 verified by direct inspection and the performing of simple 

 experiments; but the explanation of its properties in terms 

 of atomic structure can be verified only by elaborate tech- 

 niques which are designed to show what properties copper 

 would exhibit if its structure were of a certain supposed 

 character. Hence verification of symbols for explanatory 

 entities is in terms of their logical consequents, not in terms 

 of the entities themselves as in the case of descriptive sym- 

 bols. 



This affords a convenient foundation for the distinction 

 between description and explanation. An event is described 

 by those symbols which refer to it directly, and it is ex- 

 plained by those symbols which imply other symbols refer- 

 ring to the event directly. Description is thus the limit to 

 which explanation approximates when the events to which 

 it refers become more and more clearly given, and explana- 

 tion is the limit to which description approximates when the 

 properties to which it refers become more and more obscurely 

 given. The situation may be diagrammed as follows: 



SYMBOLS 



EVENTS 



(Description) 



o 



• 1-4 

 ■*-> 



q 



13, 



y ^ (Obscurely Given) 



a 



o 



-t-> 

 a 

 a 



'a 



Description 



x w (Clearly Given) 



In the strictest sense of the words 'description" and "ex- 

 planation," X may be said to describe x and Y may be said 

 to explain X; thus description is a relation of symbols to 

 events, and explanation is a relation between symbols. But 

 according to a more generous use of the word "explanation" 

 Y may be said to explain x, i.e., a symbol may be said to 

 explain an event. Now if one adopts the realistic view in 

 science and maintains that a symbol cannot explain an event 



