470 ^ KANSAS CITY REVIEW OF SCIENCE. 



distinguish between questions concerning the origin of an idea and a doubt of its 

 reality." 



The holder of the inferential theory and the holder of the theory of natural 

 realism agree that the first two steps necessary to a cognition of matter are, first, 

 an impression on the bodily organism; secondly, a sensation in the mind. The 

 third step is, according to the inferential or "sensation" school, an inference that 

 there must be something outside of the mind exerting its influence upon it, and 

 corresponding to the impression, according to the Natural Realist, thought. 



The Natural Realist objects to the third step taught by the "sensation 

 school," that it is " but an old error under a new form. It tells us nothing more 

 nor less than that the mind contemplates a sensation instead of the material ob- 

 ject. But a sensation is one thing, and a knowledge of the external world is 

 another thing. From the fact that there is an unextended sensation in the mind, 

 we can never infer that there is sornething extended outside of the mind, which 

 creates this sensation. Furthermore, no connection whatever can be traced be- 

 tween a sensation and the object creating the sensation." The Natural Realist 

 says that his view may seem to disagree with the idea of " immediate perception,"' 

 but " every sensation is joined with an immediate perception or belief in the exist- 

 ence of the external object ! " Does the Natural Realist prove to us anything 

 more than that the mind contemplates a sensation instead of the external object ? 

 And if, from the fact that there is an unextended sensation in the mind, we can 

 never infer that there is something extended, outside of the mind, which creates 

 this sensation, we are no better warranted in implicitly believing, as does the 

 Natural Realist, in the existence of an external object and then claiming that we 

 have an immediate perception of the external object. If no connection can be 

 traced between a sensation and the object creating the sensation, we certainly 

 have little reason for inferring that a material external object exists, certainly 

 much less for believing so. The thought that leads us to believe that the sensa- 

 tion in the mil d, of which alone we are certain, is produced by an external ob- 

 ject exerting an influence on the mind, may not be as correct or as mature, for 

 aught we know, as that which leads some one else to believe that esse=percipi. 



When Dr. Witherspoon was President of Princeton College, the Berkelerian 

 philosophy had been adopted by most of the professors and students. The doc- 

 tor, however, was opposed to it, and once threw out this argument against it : 

 "Young gentlemen, if you think there is nothing but ideas in the worldj just go 

 out on the campus and butt your heads against the college walls; you will, at least, 

 get an idea of matter." This objection, that the intuitive convictions of the Ideal- 

 ist lead him to act inconsistently with his theory, does not hold good, for he main- 

 tains that the universe is permanent in its ideas, and also in its laws, — that is, the 

 Eternal Spirit constantly sustains and presents these ideas for the contemplation 

 of created spirits according to fixed laws. The Idealist, therefore, acts in perfect 

 consistency with his theory. A student who would have been foolish enough to 

 have followed Dr. Witherspoon's jocular direction would, in doing so, have acted 

 regardless of those fixed laws, and in consequence, would have had some very 



