Difficulties and Methods 21 



Even what we call sensation is known to each man only 

 in himself, since it is something subjective. We possess 

 the capacity of modifying our behavior [i.e. of learning], 

 and every one knows from his own experience that psychic 

 qualities play a part connected with this modifying process. 

 Every statement that another being possesses psychic 

 qualities is a conclusion from analogy, not a certainty ; it 

 is a matter of faith. If one wishes to draw this analogical 

 inference, it should be made where the capacity for modi- 

 fication can be shown. When this is lacking, there is not 

 the slightest scientific justification for assuming psychic 

 qualities. They may exist, but there is no probability 

 of it, and hence science should deny them. Hence if one 

 ventures to speak of a Psych in animals at all, one should 

 give the preference to those which can modify their be- 

 havior" (51). But that Bethe himself prefers not to make 

 the venture is evident from statements in the text of the 

 same article. The psychic or subjective, he says, is un- 

 knowable, and the only thing we may hope to know any- 

 thing about is the chemical and physiological processes 

 involved. "These chemo-physical processes and their 

 consequences, that is, the objective aspect of psychic 

 phenomena, and these alone, should be the object of 

 scientific investigation" (51). 



Together with Beer and von Uexklill, Bethe shortly 

 afterward published " Proposals for an Objectifying Nomen- 

 clature in the Physiology of the Nervous System." The 

 main purpose of this paper was to suggest that all terms 

 having a psychological implication, such as sight, smell, 

 sense-organ, memory, learning, and the like, be carefully 

 excluded from discussions of animal reactions to stimula- 

 tion and animal behavior generally. In their stead the 

 authors propose such expressions as the following: for 



