44 The Universe and Life 



emotion and its characteristic physical condition are 

 always together; they are in effect one. And this is 

 true for all mental states and their corresponding 

 physical conditions. 



This experimental inseparability, this oneness, of 

 the given mental state and its characteristic accom- 

 panying physical condition, is the decisive point for 

 the answer to our question as to whether it is the men- 

 tal state or the physical state that causes the action ; 

 whether the way I vote is due to my opinion of the 

 candidates or to my physical condition while I hold 

 this opinion. Since the particular mental state — the 

 opinion or purpose or sensation — cannot be separated 

 from the particular physical state,^ but is, so far as 

 experimentation goes, one with it, there is no possible 

 experimental ground for asserting that one of these 

 two things brings about the action to the exclusion of 

 the other. And this means that there is no scientific 

 ground for such an assertion. It cannot be asserted 



1 It is sometimes pointed out, as if it were inconsistent with the 

 principle stated in the text, that the same gross final result that is 

 produced by an action which is preceded by a purpose or other 

 mental state may in other cases be produced without a purpose. I 

 may of purpose remove a picture from the wall; or a gust of wind 

 may likewise remove the picture from the wall. It is, of course, a 

 well-known principle that a given final result may be produced in 

 many different ways. But to conclude from this that the purpose 

 plays no part in the cases where it is present is as futile and un- 

 justified as to conclude that the gust of wind plays no part in the 

 cases where it is present. The only test in either case is to remove 

 the suspected factor, leaving all other conditions the same, and thus 

 to discover whether that factor plays a role. 



Again, one may of set purpose strike a particular note on the 

 piano, and later, after long practice, one may, in the course of play- 

 ing a composition that one has learned by heart, strike the same note 

 without the set purpose directed upon that particular note. From 



