Preface 



The book is not a treatise on all cerebral mechanisms but a pro- 

 posed solution of a specific problem: the origin of the nervous 

 system's unique ability to produce adaptive behaviour. The 

 work has as basis the fact that the nervous system behaves adap- 

 tively and the hypothesis that it is essentially mechanistic; it 

 proceeds on the assumption that these two data are not irrecon- 

 cilable. It attempts to deduce from the observed facts what sort 

 of a mechanism it must be that behaves so differently from any 

 machine made so far. Other proposed solutions have usually left 

 open the question whether some different theory might not fit the 

 facts equally well: I have attempted to deduce what is necessary, 

 what properties the nervous system must have if it is to behave 

 at once mechanistically and adaptively. 



For the deduction to be rigorous, an adequately developed logic 

 of mechanism is essential. Until recently, discussions of mechan- 

 ism were carried on almost entirely in terms of some particular 

 embodiment — the mechanical, the electronic, the neuronic, and so 

 on. Those days are past. There now exists a well developed 

 logic of pure mechanism, rigorous as geometry, and likely to play 

 the same fundamental part, in our understanding of the complex 

 systems of biology, that geometry does in astronomy. Only by 

 the development of this basic logic has the work in this book been 

 made possible. 



The conclusions reached are summarised at the end of Chapter 

 18, but they are likely to be unintelligible or misleading if taken 

 by themselves; for they are intended only to make prominent the 

 key points along a road that the reader has already traversed. 

 They may, however, be useful as he proceeds, by helping him to 

 distinguish the major features from the minor. 



Having experienced the confusion that tends to arise whenever 

 we try to relate cerebral mechanisms to observed behaviour, I 

 made it my aim to accept nothing that could not be stated in 

 mathematical form, for only in this language can one be sure, 

 during one's progress^ that one is not unconsciously changing the 



