RELATIONS OF LOGIC TO OTHER DISCIPLINES 309 



overlap. Lipps, in his Grundziige der Logik (p. 2), goes the length 

 of saying that "Logic is a psychological discipline, as certainly as 

 knowledge occurs only in the Psyche, and thought, which is developed 

 in knowledge, is a psychical event." Now, if we were to take such 

 extreme ground as this, then ethics, aesthetics, and pure mathe- 

 matics would become at once branches of psychology and not coor- 

 dinate disciplines with it, for volitions, the feelings of appreciation, 

 and the reasoning of pure mathematics are psychical events. Such 

 a theory plainly carries us too far and would involve us in confusion. 

 That the demarcation between the two disciplines is not a chasmic 

 cleavage, but a line, and that, too, an historically shifting line, is 

 apparent from the foregoing historical resume. 



The four main phases of logical theory include: (1) the concept 

 (although some logicians begin with the judgment as temporally 

 prior in the evolution of language), (2) judgment, (3) inference, (4) the 

 methodology of the sciences. The entire concern of logic is, indeed, 

 with psychical processes, but with psychical processes regarded from 

 a specific standpoint, a standpoint different from that of psychology. 

 In the first place psychology in a certain sense is much wider than 

 logic, being concerned with the w T hole of psychosis as such, including 

 the feelings and will and the entire structure of cognition, whereas 

 logic is concerned with the particular cognitive processes enumer- 

 ated above (concept, judgment, inference), and that, too, merely 

 from the point of view of validity and the grounds of validity. In 

 another sense psychology is narrower than logic, being concerned 

 purely with the description and explanation of a particular field of 

 phenomena, whereas logic is concerned with the procedure of all the 

 sciences and is practically related to them as their formulated 

 method. The compass and aims of the two disciplines are different; 

 for while psychology is in different references both wider and nar- 

 rower than logic, it is also different in the problems it sets itself, 

 its aim being to describe and explain the phenomena of mind in the 

 spirit of empirical science, whereas the aim of logic is only to explain 

 and establish the laws of evidence and standards of validity. Logic 

 is, therefore, selective and particular in the treatment of mental 

 phenomena, whereas psychology is universal, that is, it covers 

 the entire range of mental processes as a phenomenalistic science; 

 logic dealing with definite elements as a normative science. By this 

 it is not meant that the territory of judgment and inference should 

 be delivered from the psychologist into the care of the logician; 

 through such a division of labor both disciplines would suffer. The 

 two disciplines handle to some extent the same subjects, so far as 

 names are concerned ; but the essence of the logical problem is not 

 touched by psychology, and should not be mixed up with it, to the 

 confusion and detriment of both disciplines. The field of psychology, 



