CHAPTER 1 



The Problem 



1/1. How does the brain produce adaptive behaviour ? In 

 attempting to answer the question, scientists have discovered two 

 sets of facts and have had some difficulty in reconciling them. 

 The physiologists have shown in a variety of ways how closely the 

 brain resembles a machine : in its dependence on chemical 

 reactions, in its dependence on the integrity of anatomical paths, 

 and in many other ways. At the same time the psychologists 

 have established beyond doubt that the living organism, whether 

 human or lower, can produce behaviour of the type called 4 pur- 

 poseful ' or ' intelligent ' or ' adaptive ' ; for though these words 

 are difficult to define with precision, no one doubts that they 

 refer to a real characteristic of behaviour. These two character- 

 istics of the brain's behaviour have proved difficult to reconcile, 

 and some workers have gone so far as to declare them incom- 

 patible. 



Such a point of view will not be taken here. I hope to show 

 that a system can be both mechanistic in nature and yet 

 produce behaviour that is adaptive. I hope to show that the 

 essential difference between the brain and any machine yet made 

 is that the brain makes extensive use of a principle hitherto 

 little used in machines. I hope to show that by the use of this 

 principle a machine's behaviour may be made as adaptive as we 

 please, and that the principle may he capable of explaining even 

 the adaptiveness of Man. 



But first we must examine more closely the nature of the 

 problem, and this will be commenced in this chapter. The suc- 

 ceeding chapters will develop more accurate concepts, and when 

 we can state the problem with precision we shall be not far from 

 its solution. 



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