Nature of Evolutionary Progress 35 



from data existing at the earliest periods it would be 

 in principle possible to compute your behavior, my 

 behavior, the behavior of all men, the entire course of 

 human history. Sensations, emotions, desires, pur- 

 poses, and knowledge would not come into this com- 

 putation, so that when these things come into exist- 

 ence, from this point of view, they do not influence 

 the movements that occur ; for these movements could 

 be computed without taking them into consideration. 

 The same physical conditions, without the mental 

 states, this theory holds, would produce the same 

 behavior. The fact that I am hungry (that is, that I 

 have sensations of hunger) has nothing to do with 

 the fact that I eat; in general, the fact that hunger 

 occurs in the universe has nothing to do with the fact 

 that eating occurs in the universe. The fact that I 

 have some knowledge of biology has nothing to do 

 with the fact that I give lectures on that subject; I 

 would give exactly the same lectures if I had no such 

 knowledge. The opinions that I hold, the thinking I 

 have done, have nothing to do with what I am saying 

 to you. Such is the thoroughgoing doctrine of 

 mechanism. 



Is this doctrine sound .^ Must we hold that feelings 

 and ideas and knowledge and purposes have no func- 

 tion in the world; that they make no difference to 

 what happens.? No question can be more important 

 for our outlook on the world. We shall therefore 

 examine in some detail this question, of the validity of 

 this widely accepted doctrine of mechanism. 



Argumentation in support of this doctrine has 



