CHAPTER 13 



The System with Local Stabilities 



13/1. Having examined what is meant by a system that has 

 ' partial, fluctuating, and temporary independencies within the 

 whole ' we can now consider some of the properties that a system 

 of such a type will show in its behaviour. 



In saying 4 a system of such a type ' we have not, of course, 

 defined a system with precision: we have only defined a set or 

 class of systems. How shall we achieve precision ? Two ways 

 are open to us. 



One way is to add further details until we have defined a parti- 

 cular system with full precision, so that its behaviour is deter- 

 minate and uniquely defined; we then follow the behaviour in all 

 detail. Such a study would give us an exact conclusion, but it 

 would give us far more detail than we require, or can conveniently 

 handle, in the remaining chapters. 



Another way is to talk about such systems ' in general '. Here 

 nothing is easier than to relax our grasp and to talk vaguely about 

 what will ' usually ' happen, regardless of the fact that whether 

 particular properties (such as linearity, or the presence of thres- 

 hold) are ' usually ' present differs widely in the systems of the 

 sociologist, the neurophysiologist, and the physicist. Rigour and 

 precision are possible while speaking of systems ' in general ' 

 provided two requirements are met: the set of systems under 

 discussion must be defined precisely, and statements made must 

 be precise statements about the properties of the set. In other 

 words, we give up the aim of being precise about the individual 

 system, and accept the responsibility of being precise about the 

 set. This second way is the method we shall largely follow in the 

 remaining chapters. 



Having changed to the new aim, we shall often find that the 

 argument about the set is conducted most readily in terms of 

 some individual system that is followed in detail; when this 

 happens, the individual system must be understood to have 



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