iv MECHANISM AND TELEOLOGY 321 



purpose, the train of events which it sets up and the ulti- 

 mate end are seen as an organic whole, in which each element 

 owes its existence to its relation to the remainder. Con- 

 versely, an organic whole is one which is determined by a 

 purpose. The two forms of purpose discriminated above 

 (p. 313) must in the last resort come down to one. Of 

 course, it remains true that in a machine the configuration 

 is imposed ab extra on an indifferent material. But pre- 

 cisely so far as this is true, the existence of the material 

 remains outside and unexplained by the purpose. All that 

 falls within the purpose, the shaping and arrangement of 

 parts, owes its existence to the purpose and contributes to 

 it, and so forms an organic whole. Conversely, the bare 

 existence of the material is a datum left unexplained by the 

 purpose. So far then as there is explanation of colloca- 

 tions, it is by reference to a purpose which is also a principle 

 of organic unity. 



But all this only shows that the teleological concept is 

 logically possible. It does not prove that it actually 

 applies to anything in the real world. How are we to 

 decide this question? There are two possible lines of 

 approach, (i) First, we may continue to follow the logic 

 of explanation. We have seen that, when we explain the 

 existence of any thing or any process in a particular space 

 and time relation to other things, we do so by assigning to it 

 a certain place in a system. This raises the question of the 

 explanation of the system itself, and here we saw two possi- 

 bilities. The parts of a system might be mutually indif- 

 ferent, in which case they must be brought together by 

 some external agent, whose action could be explained if it 

 served some purpose. Or the parts might necessitate one 

 another, in which case, in the end, their existence and 

 activity must be regarded as determined by their functions, 

 i.e. by their tendency to produce certain results. In either 

 case the explanation was teleological, and we have now seen 

 further that teleological explanation is something intrinsi- 

 cally possible, self-consistent, and radically different from 

 mechanical causation. Still our only positive result so far 

 is to show that in two contrasted cases collocations can be 

 explained by showing that they serve a purpose. We have 



