V 

 PSYCHO-PHYSICAL METHOD 



(W. McDoUGALL) 



IT is my business to illustrate for you the application 

 of the scientific method to that highly specialized and 

 difficult branch of science known as psycho-physics. I 

 propose to do this by defining one particular psycho- 

 physical problem, typical of many psycho-physical pro- 

 blems, and showing you the difficulties in the way of 

 its solution and the manner in which these difficulties 

 may be, in large part at least, overcome. 



But it is perhaps desirable that, before I do this, 

 I should say something of the nature of psycho-physical 

 science in general, of its scope and aims, and of its 

 relations to other branches of science. This is neces- 

 sary because, unlike most of the departments of science 

 that you will hear discussed in this course of lectures, 

 psycho-physics is a very young science. It came into 

 existence hardly half a century ago, and therefore is 

 still somewhat amorphous ; its boundaries cannot be 

 sharply drawn, its methods are still in process of forma- 

 tion, and even its most fundamental conceptions are in an 

 unstable state and are the subject of perpetual discus- 

 sions which reveal wide differences of opinion among 

 the workers. 



It is for these reasons that, even in addressing a 

 cultured audience such as this, it is desirable to attempt 



