148 INTRODUCTION TO PHILOSOPHY OF SCIENCE 



tions, or by conventions? Are such things as atoms merely 

 conceptual shorthand, or are they existent events? What 

 is the difference between such things as molecules which 

 presumably could exist, and perfect levers which presumably 

 could not exist? Such questions as these demand answer if 

 an adequate logic of science is to be constructed. 



A satisfactory classification of the various answers to 

 these questions is very difficult to make, for it itself pre- 

 supposes a general theory of the logic of science. The 

 classification which is here proposed is offered merely as a 

 convenient method for presenting the theories which are 

 to be discussed in this chapter. It makes no claim to general 

 adequacy. The names listed in connection with each of the 

 positions are those of the outstanding recent and contempo- 

 rary representatives. The names in italics designate those 

 individuals whose views will be considered as illustrative of 

 the general positions. 



A. Positivisms 



1. Strict Empiricism: Mill, Mach, Pearson 



2. Operationalism : Bridgman 



B. Modified Positivisms (Fictionalisms) 



1. Constructionalism : Russell, Hobson 



2. Conventionalism: Vaihinger, Poincare 



3. Logical Positivism: Schlick, Wittgenstein, Carnap 



C. Realisms 



Scientific Realism: Planck, Meyerson, Whitehead, Bavink 



The principles underlying this table are as follows : Grant- 

 ing that the task of science is the construction of a system 

 of symbols having a certain representative value toward the 

 realm of events, the important problem is to determine in 

 just what way the system has been built up. Presumably 

 the simplest formulation of this task is to say that the sci- 

 entist confronts himself with the data, sets into operation 

 certain activities usually called "knowing" or "thinking," 

 and ends with the required system of symbols. This formu- 

 lation, at any rate, indicates clearly that the symbols are 



