414 READINGS IN BIOLOGICAL SCIENCE 



purpose do so for a purpose, and thereby contradict themselves. The very 

 la\\s of mechanics used as a basis for explaining the behavior of things non- 

 purposivelv were formulated by human minds for a purpose. Alechanists 

 would be the first to discard those mechanical laws which were not suited 

 to their purposes." 



Mechanists reply that the claimed contradiction is only an apparent one, 

 not a real one. For mechanists explain purpose in nonpurposive, or mechani- 

 cal, terms. Purpose is a notion in a casually (non-purposively) determined 

 mind. Even if the mechanist seems to those who interpret things pur- 

 posively to be acting purposively, he claims that such purposes are mechani- 

 cally caused. Thus he involves no contradiction. 



Proof by inechmiists. "Since every normal person seems to himself at 

 times to act for a purpose, everyone must admit that there are at least hu- 

 man purposes in the world. If, as mechanists claim, the world is uniform, 

 then if there is purpose in part of it, why not also in all of it? Furthermore, 

 since, for the mechanists, nothing can occur spontaneously but everything 

 must have a cause that is capable of causing it, purposes which do exist 

 must have been caused, and in order for them to have been caused 

 there must have existed in the world other prior purposes capable of causing 

 them. These prior purposes must have been caused by still earlier purposes, 

 either backward infinitely or by somx first or ultimate purpose. Thus 

 mechanism really presupposes world purposiveness." 



Mechanists may grant that personal purposes constitute a part of the 

 world, but maintain that it does not follow that the whole world is made 

 up of personal purposes nor that the world as a w^hole has a purpose. "Uni- 

 formity of nature" does not mean that everything is alike, but only that 

 when a given set of causal conditions recurs there will result an exactly 

 similar set of efi^ects. Argument from parts to whole are unwarranted, as 

 can be seen from the example of a worm in a partly rotten apple. If he is 

 in the rotten part, it may seem all rotten. If he is in the good part, it may 

 seem all good. If he is on the border between the two, it may seem either 

 a good apple with a rotten part or a rotten apple with a good part. One 

 might just as easily argue for non-purposiveness of the whole world on 

 similar grounds, for everyone will admit also that some experiences seem 

 lacking in purpose. 



Unprovability of jtiechanism. "Since human knowledge is limited and 

 since there is much about the universe that we can never know, mechanists 

 can never prove conclusively that the world has no purpose. For even if it 

 were provable that everything in the known universe is non-purposive, 

 it still would not follow that the rest of the universe which we do not know 

 is non-purposive. So long as complete mechanism is unprovable, it is 

 reasonable to suppose that teleology is true." 



Mechanists reply with almost exactly the same argument. "Since human 

 knowledge is limited and there is a part of the world which we shall never 



