1/7 THE PROBLEM 



power. The nervous system, then, possesses almost unlimited 

 potentialities for action. But do these potentialities solve our 

 problem ? It seems not. We are concerned primarily with the 

 question why, during learning, behaviour changes for the better: 

 and this question is not answered by the fact that a given behaviour 

 can change to one of 4 lesser or greater activity. The examples 

 given in S. 1/5, when examined for the energy changes before and 

 after learning, show that the question of the quantity of activity 

 is usually irrelevant. 



But the evidence against regarding mere activity as sufficient 

 for a solution is even stronger : often an increase in the amount of 

 activity is not so much irrelevant as positively harmful. If a 

 dynamic system is allowed to proceed to vigorous action without 

 special precautions, the activity will usually lead to the destruction 

 of the system itself. A motor car with its tank full of petrol may 

 be set into motion, but if it is released with no driver its activity, 

 far from being beneficial, will probably cause the motor car to 

 destroy itself more quickly than if it had remained inactive. The 

 theme is discussed more thoroughly in S. 20/10; here it may be 

 noted that activity, if inco-ordinated, tends merely to the system's 

 destruction. How then is the brain to achieve success if its 

 potentialities for action are partly potentialities for self-destruction? 



The relation of part to part 



1/7. Our basic fact is that after the learning process the behaviour 

 is usually better adapted than before. We ask, therefore, what 

 property must be possessed by the neurons so that the manifesta- 

 tion by the neuron of this property shall result in the whole 

 organism's behaviour being improved. 



A first suggestion is that if the nerve-cells are all healthy and 

 normal as little biological units, then the whole will appear healthy 

 and normal. This suggestion, .however, must be rejected as 

 inadequate. For the improvement in the organism's behaviour 

 is often an improvement in relation to entities which have no 

 counterpart in the life of a neuron. Thus when a dog, given food 

 in an experiment on conditioned responses, learns to salivate, the 

 behaviour improves because the saliva provides a lubricant for 

 chewing. But in the neuron's existence, since all its food arrives 

 in solution, neither ' chewing ' nor ' lubricant ' can have any direct 



5 



