DESCRIPTIVE SCIENCE 133 



solipsism. According to Norman Campbell what the sci- 

 entist investigates is not a private world but a public one, 

 for "science is the study of those judgments concerning 

 which universal agreement can be obtained." 1 Again, 

 Emile Meyerson, one of the most energetic of the critics of 

 subjectivism in science, writes, "There can be no doubt 

 from the start as to the mental attitude of the physicist 

 who studies nature; he does not believe at all that he is 

 investigating merely the relations between sensations, but, 

 on the contrary, that he is penetrating into a mystery 

 which is independent of his sensation." 2 The given, there- 

 fore, includes not merely sense-impressions, but public and 

 external objects, beyond which all else is inference and 

 construction. But still other writers, recognizing the vari- 

 ability in the clarity with which objects may be given, 

 insist that the data of science are even more extensive. 

 Hypothetical entities, such as molecules and electrons, are, 

 according to Whitehead, natural objects. "Scientific laws, 

 if they are true, are statements about entities which we 

 obtain knowledge of as being in nature ... if the entities 

 to which the statements refer are not to be found in nature, 

 the statements about them have no relevance to any purely 

 natural occurrence. Thus the molecules and electrons of 

 scientific theory are, so far as science has correctly formu- 

 lated its laws, each of them factors to be found in nature." 3 

 Since nature consists of all those events which are given 

 in a definable sense, and there is a definable sense in which 

 molecules and electrons are given, it follows that they are 

 natural objects. The given, therefore, includes not merely 

 sense-impressions and external objects but a large number 

 of entities not even theoretically observable. But if the 

 given is sufficiently flexible to include both an extreme 

 solipsism and a radical realism, there seems only one con- 

 clusion to be drawn. The given must be a variable. 



But even if one grants that science is bound to admit the 



1 What Is Science? (London: Methuen, 1926), p. 27. 



2 De V explication dans les sciences (Paris: Payot, 1927), p. 33. 



3 Concept of Nature, pp. 45-46. 



