DESIGN FOR A BRAIN 2/17 



The third property makes clear that we cannot expect a proposed 

 definition to be established by a few lines of verbal argument: 

 it must be treated as a working hypothesis and used ; only experi- 

 ence can show whether it is faulty or sound. (Nevertheless, in 

 J. to C, S. 13/5, I have given reasons suggesting that the property 

 of being state-determined must inevitably be of fundamental 

 interest to every organism that, like the human scientist, wants 

 to achieve mastery over its surroundings.) 



Because of its importance, science searches persistently for the 

 state-determined. As a working guide, the scientist has for some 

 centuries followed the hypothesis that, given a set of variables, 

 he can always find a larger set that (1) includes the given variables, 

 and (2) is state-determined. Much research work consists of 

 trying to identify such a larger set, for when the set is too small, 

 important variables will be left out of account, and the behaviour 

 of the set will be capricious. The assumption that such a larger 

 set exists is implicit in almost all science, but, being fundamental, 

 it is seldom mentioned explicitly. Temple, though, refers to 

 4 . . . the fundamental assumption of macrophysics that a com- 

 plete knowledge of the present state of a system furnishes sufficient 

 data to determine definitely its state at any future time or its 

 response to any external influence \ Laplace made the same 

 assumption about the whole universe when he stated that, given 

 its state at one instant, its future progress should be calculable. 

 The definition given above makes this assumption precise and 

 gives it in a form ready for use in the later chapters. 



The assumption is now known to be false at the atomic level. 

 We, however, will seldom discuss events at this level; and as the 

 assumption has proved substantially true over great ranges of 

 macroscopic science, we shall use it extensively. 



Strategy for the complex system 



2/17. The discussion of this chapter may have seemed confined 

 to a somewhat arbitrary set of concepts, and the biologist, accus- 

 tomed to a great range of variety in his material, may be thinking 

 that the concepts and definitions are much too restricted. As this 

 book puts forward a theory of the origin of adaptation, it must 

 show how a theory, developed so narrowly, can be acceptable. 

 In this connexion we must note that theories are of various 



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