612 PSYCHOLOGY 



III. The Postulates of Modern Scientific Psychology 



From the preceding exposition, I may venture to draw certain 

 inferences of a negative sort: statements of what the thought of 

 the earlier centuries lacked; and follow that with the positive 

 characters belonging to the nineteenth-century science. 



What the earlier thinkers lacked, then, was (1) a full natural- 

 ism in their point of view: a naturalism which could follow only 

 upon a critical dualism of mind and body. Grant the dualism of 

 inner and outer, take the further step to that of mind and body, 

 then and this is the needful thing for naturalism admit the 

 oneness of the knowledge of nature as a whole in the face of the 

 cleft in nature which the dualism postulates. The thinkers we have 

 been considering did not achieve this last step. They worked out 

 their theoretical interest by establishing a philosophical solution 

 of the dualism, or, on the other hand, resorted to an esthetic 

 handling of it. 



(2) They did not achieve a positive way of treating all data 

 as material of knowledge as such, material to be progressively 

 systematized and enlarged by research. The former is the full 

 scientific point of view; the latter is its method and instrument. 



What modern psychology has in addition is just the something 

 that these early thinkers lack: 



(1) Naturalism, 1 or the view that all events or phenomena what- 

 ever are part of a natural order, and are subject to general and 

 ascertainable rules of sequence. 



(2) Positivism, 1 or the view that a methodology a theory 

 and practice of method of research is possible, for the discovery 

 of the rules or laws which govern the sequences of the natural world. 



Both of these scientific postulates hold for psychology. They 

 have long been established in the physical or exact-quantitative 

 sciences; they have been slow of formulation in the biological 

 sciences; they are only beginning to have adequate recognition - 

 especially, the second of them in the mental and moral sciences. 

 It is the characteristic feature of nineteenth-century psychology, 

 that it has developed the first of these postulates fully and the 

 second partially. 



IV. History of Nineteenth-Century Psychology 



The nineteenth century opened at a natural pause in the evo- 

 lution of theories about the mind. In the flow of the great cur- 

 rents, certain eddies had formed late in the eighteenth century. 



1 It should be noted that I speak of scientific, not of philosophical naturalism 

 and positivism. 



