Some Comments on Cybernetics and Control

The theory of cybernetics as introduced by Ashby and developed by Ashby and Conant will be analyzed and commented upon. Ashby's law of requisite variety and, in particular, the underlying measure of optimality-the quantity of entropy-are examined. Next the cybernetic theorem of error control and cause control is observed, and finally the cybernetic theorem of the necessity of modeling for regulation is studied. In all three cases several practical conditions and restrictions for the applicability of the theorems to control engineering are pointed out.