Here the important question of the relation of general system theory and cybernetics, of open systems and regulatory mechanisms appears (cf. pp. 160ff.). In the present context a few remarks will suffice.
The basis of the open-system model is the dynamic interaction of its components. The basis of the cybernetic model is the feedback cycle (FIG. 1.1) in which, by way of feedback of information, a desired value (Sollwert) is maintained, a target is reached, etc. The theory of open systems is a generalized kinetics and thermodynamics. Cybernetic theory is based on feedback and information. Both models have, in respective fields, been successfully applied. However, one has to be aware of their differences and limitations.
The open-system model in kinetic and thermodynamic formulation does not talk about information. On the other hand, a feedback system is closed thermodynamically and kinetically; it has no metabolism.
In an open system increase of order and decrease of entropy is thermodynamically possible. The magnitude, “information,” is defined by an expression formally identical with negative entropy. However, in a closed feedback mechanism information can only decrease, never increase, i.e., information can be transformed into “noise,” but not vice versa.
An open system may “actively” tend toward a state of higher organization, i.e., it may pass from a lower to a higher state of order owing to conditions in the system. A feedback mechanism can “reactively” reach a state of higher organization owing to “learning,” i.e., information fed into the system.
In summary, the feedback model is preeminently applicable to “secondary” regulations, i.e., regulations based on structural ar- rangements in the wide sense of the word. Since, however, the structures of the organism are maintained in metabolism and exchange of components, “primary” regulations must evolve from the dynamics in an open system. Increasingly, the organism becomes “mechanized” in the course of development; hence later regulations particularly correspond to feedback mechanisms (homeostasis, goal-directed behavior, etc.).
The open-system model thus represents a fertile working hy- pothesis permitting new insights, quantitative statements and experimental verification. I would like, however, to mention some important unsolved problems.
Source: Bertalanffy Ludwig Von (1969), General System Theory: Foundations, Development, Applications, George Braziller Inc.; Revised edition.