90 ROYCE— PRINCIPLES OF THEORETICAL SCIENCE. [April 19 



concerning the office and conceptions of recent psychology, the whole 

 range of researches in modern group theory ; and in brief, all the 

 more enlightened types of recent reflection upon the principles of 

 science. Although myself a student of philosophy, I lay here no 

 stress upon the contributions to this research which have in my opin- 

 ion been due to the progress of modern philosophy viewed as such. 

 There is no reason to consider the philosophers in this field as either 

 a. privileged or a dangerous class, or as for that matter easily a sep- 

 arable class. Cantor and Dedekind are philosophers amongst the 

 mathematicians. I suppose it might be fair to call Mr. Bertrand 

 Russell mathematician amongst the philosophers. I am certain that 

 Mr. Charles Peirce is a philosopher. I am certain that Boole, al- 

 though a mathematician, was guided by profoundly philosophical in- 

 stincts. My interest at this moment is in laying stress upon the fact 

 that the modern study of this subject is confined to no one branch 

 of students, and on the other hand has so far developed that in this 

 field one is no longer confined to the chance observations of this or 

 of that introspective philosopher concerning what he happens to have 

 noted regarding his personal thinking processes. The science which 

 now deals with the morphology of theories, which seeks for their 

 fundamental concepts, which tries to detect what unity there is 

 amongst these concepts, which endeavors to show wherein lies the 

 advantage which certain concepts possess for the purposes of theoret- 

 ical construction, this whole science, I say, is now no longer a mat- 

 ter of merely private scrutiny, and of personal opinion. It is full of 

 still unsolved problems ; but it has a definite method of work. This 

 method, like that of other sciences, is itself at once empirical and 

 theoretical. Empirically the student of logic treats scientific theories 

 as themselves facts which the history of science presents for his in- 

 spection. He analyzes these theories to see what their conceptual 

 structure is. A comparative study of theories shows him the prev- 

 alence and the importance of certain types of concepts, such for in- 

 stance as the concept of quantity itself. The student hereupon un- 

 dertakes to analyze these various concepts into their elements, to de- 

 tect what their structure is, to describe them as one would describe 

 organisms or solar systems. He then proceeds to ask in what ways 

 the structure of such theories is determined by the nature of human 



