12/18 



TEMPORARY INDEPENDENCE 



12/16. These deductions can now be joined to those of S. 12/10. 

 If three subsystems are joined so that their diagram of immediate 

 effects is 



and if B is at a state that is equilibrial for all values coming from 

 A and C, then A and C are (unconditionally) independent. Thus, 

 Z?'s being at a state of equilibrium severs the functional connexion 

 between A and C. 



Suppose now that 2?'s states are equilibrial for some states of 

 A and C, but not for others. As A and C, on some line of behaviour 

 of the w r hole system, pass through various values, so will they 

 (according to whether 2?\s state at the moment is equilibrial or 

 not) be sometimes dependent and sometimes independent. 



Thus we have achieved the first aim of this chapter: to make 

 rigorously clear, and demonstrable by primary operations, what 

 is meant by ' temporary functional connexions ', when the control 

 comes from factors within the system, and not imposed arbitrarily 

 from outside. 



12/17. The same ideas can be extended to cover any system as 

 large and as richly connected as we please. Let the system consist 

 of many parts, or subsystems, joined as in S. 6/6, and thus pro-, 

 vid'ed with basic connexions. If some of the variables or sub- 

 systems are constant for a time, then during that time the con- 

 nexions through them are reduced functionally to zero, and the 

 effect is as if the connexions had been severed in some material 

 way during that time. 



If a high proportion of the variables go constant, the severings 

 may reach an intensity that cuts the whole system into subsystems 

 that are (temporarily) quite independent of one another. Thus a 

 whole, connected system may, if a sufficient proportion of its 

 variables go constant, be temporarily equivalent to a set of un- 

 connected subsystems. Constancies, in other words, can cut a 

 system to pieces. (I. to C, S. 4/20, gives an illustration of the fact.) 



12/18. The field of a state-determined system whose variables 

 often go constant has only the peculiarity that the lines of 

 behaviour often run in a sub-space orthogonal to the axes. Thus, 



169 



