THE PURPOSES OF BEHAVIOUR 135 



can be inferred from the structure (though not without an in- 

 dispensable knowledge). Thus w^e should infer the working of 

 a clock from a knowledge of mechanics, but we should not be 

 able, on this basis alone, to infer the working of a dynamo from 

 its structure (a knowledge of Faraday's laws of induction would 

 be necessary). When we know the structure, with the above 

 qualifications, we can predict how the machine works even when 

 we have not observed it working. This would be the case 

 even if the machine were automatically to regulate itself, for the 

 regulator is of the same order of structure as the other parts. 

 But we should not infer, from a knowledge of the anatomy of 

 the human body, that a man may be unable to swim without 

 learning ; or, from knowing the human and chimpanzee sensori- 

 motor system, that the latter animal cannot speak ; or, from 

 knowing all the anatomy of a particular parrot, that it does speak. 

 This is because a mental mechanism is concerned in animal 

 behaviour and this is not knowable merely by inspection. 



48. ON THE PURPOSES OF BEHAVIOUR 



We can easily discover, by introspection, that an urge to do 

 something is in consciousness and has in it some feeling of need 

 or desire : thus the nutrition (or assimilation) urge is felt as 

 hunger. It is not simply '' had " in consciousness as something 

 that we know — as knowledge that food should be taken — for there 

 is emotional quality, or some consciousness deepening into pain 

 so long as we do not assimilate. On eating the urge manifests 

 itself in behaviour and there is satisfaction. We may think of 

 the satisfaction of an urge like we think of the neutralization of 

 an acid by an alkali in that stability of the acid and base system 

 is effected in the formation of a salt. But we can also easily 

 discover that the satisfaction of an urge in appropriate behaviour 

 does not merely bring about normality of consciousness — it 

 usually gives pleasure. We experience, or have, therefore, needs 

 and desires and we satisfy these needs and desires by behaviour 

 which may be undeliberately effected — as when an infant suckles, 

 or which may be accompanied by conscious states — as when a 

 man scans the menu card in a restaurant, orders his meal and then 

 eats it with the conventional behaviour. 



We extend the results of introspective analysis of our own 



