9/16 ULTRASTABILITY IN THE ORGANISM 



this will destroy the field. So U becomes ' 5-seeking '. If the 

 action of R is now changed to transmitting, not 5a — 20 but 

 5a + 5, then U will change fields until it holds A within one 

 unit of 0; and U is now ' 0-seeking'. So anything that controls 

 the b in R = 5a + b controls the ' goal ' sought by U. 



As a more practical example, suppose U is mobile and is 

 ultrastable, with its critical states set so that it seeks situations 

 of high illumination; such would occur if its critical states 

 resembled, in Figure 9/16/1, B rather than A. Suppose too that 

 R is a ray of light. If in the path of R we place a red colour- 

 filter, then green light will count as ' no light ' and the system 

 will actively seek the red places and avoid the green. If now 

 we merely replace the red filter by a green, the whole aim of 

 its movements will be altered, for it will now seek the green 

 places and avoid the red. 



Next, suppose R is a transducer that converts a temperature 

 at A into an illumination which it transmits to U. If R is 

 arranged so that a high temperature at A is converted into a high 

 illumination, then U will become actively goal-seeking for hot 

 places. And if the relation within R is reversed, U will seek 

 for cold places. Clearly, whatever controls R controls C/'s goal. 



There is therefore in general no difficulty in accounting for 

 the fact that a system may seek one goal at one time and another 

 goal at another time. 



Sometimes the change, of critical states or of the transducer 

 R. may be under the control of a single parameter. When this 

 happens we must distinguish two complexities. Suppose the 

 parameter can take only two values and the system U is very 

 complicated. Then the system is simple in the sense that it 

 will seek one of only two goals, and is complicated in the sense 

 that the behaviour with which it gets to the goal is complicated. 

 That the behaviour is complicated is no proof, or even sugges- 

 tion, that the parameter's relations to the system must be com- 

 plicated; for, as was shown in S. 6/3, the number of fields is 

 equal to the number of values the parameter can take, and has 

 nothing to do with the number of main variables. It is this 

 latter that determines, in general, the complexity of the goal- 

 seeking behaviour. 



These considerations may clarify the relations between the 

 change of concentration of a sex-hormone in the blood of a 



133 



