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. 

 On the one hand 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 the precision and determinateness with which its 

 component parts act on one another. On the other hand, the 

 psychologists and biologists have confirmed with full objectivity 

 the layman's conviction that the living organism behaves typically 

 in a purposeful and adaptive way. These two characteristics of 

 the brain's behaviour have proved difficult to reconcile, and some 

 workers have gone so far as to declare them incompatible. 



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 method hitherto little used in 

 machines. I hope to show that by the use of this method a 

 machine's behaviour may be made as adaptive as we please, and 

 that the method may be capable of explaining even the adaptive- 

 ness 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 not be far from 

 its solution. 



Behaviour, reflex and learned 



1/2. The activities of the nervous system may be divided more 

 or less distinctly into two types. The dichotomy is probably an 



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