4/16 DESIGN FOR A BRAIN 



at random there would be only an even chance that the assembly 

 would be stable. But as the system and the feedbacks become 

 more complex, so does the achievement of stability become more 

 difficult and the likelihood of instability greater. Radio engineers 

 know only too well how readily complex systems with feedback 

 become unstable, and how difficult is the discovery of just that 

 combination of parts and linkages which will give stability. 



The subject is discussed more fully in S. 20/12 : here it is 

 sufficient to note that as the number of variables increases so 

 usually do the effects of variable on variable have to be co- 

 ordinated with more and more care if stability is to be achieved. 



Reference 

 Wiener, Norbert. Cybernetics. New York, 1948. 



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