International Encyclopedia of Systems and Cybernetics

A system capable to maintain its independent existence (Adapted from St. BEER, 1989, p.11).

The Viable System Model has been introduced by S. BEER from 1966 on. At that time he wrote:

"Viable systems have the ability to make a response to a stimulus which was not included in the list of anticipated stimuli when the system was designed. They can learn from repeated experience what is the optimal response to that stimulus. Viable systems grow. They renew themselves… They are robust against internal breakdown and error. Above all, they continuously adapt to a changing environment, and by this means survive – quite possible in conditions which had not been entirely foreseen by their designer.

"Now the systems that must be handled in the economic, social and industrial worlds are indeed systems of such viable characteristics, which tend to have (when they are successful) the properties just listed. Cybernetics has demonstrated that they have these properties only if they have high complexity; they must exist beyond a certain ‘complexity barrier' to be viable" (1966, p.256).

BEER progressively developed the complex cybernetics involved in the Viable System Model. Hereafter a very condensed summary of the VSM. However, no summary can can satisfactorily resume this complex work. For a full development, see "The Heart of Enterprise" (1979).

A Viable System is made of five types of interconnected systems at different levels.

"Systems One" are frequently numerous in a complex system. Each one attends a specific process related to a specific part of the active environment of the system.

"Systems Two" are coordinating meta systems of Systems One, which have anti-oscillatory effects, or act as "input attenuators", locally and globally (p.176-7).

"Systems Three " are concerned with the general coordination and coherence between Systems One and Two (p.205-7).

"System Four" responds to the need to cope with a larger environment and an unknown future. It aims at giving a wider space (environment) and time (planning) frame to Systems Three to One. To operate correctly any System Four needs to have access to the full variety available in Systems One to Three (p.349).

"System Five", in accordance with ASHBY's Law of Requisite Variety, must contain general models of Systems Three and Four in order to be able to control through general closure, if possible, unexpected external variety. (p.352).

Unfortunately, System Five, as a "general boss" (individual or collective) is always in danger to become an autocratic power, "that will soon or later make a global mistake". (A possible way to avoid this could be the heterarchical organizational model).

While basically a model for the practical uses of management, the VS Model represents the operation of complex systems in general.

BEER's VSM relies heavily on two very basic cybernetic concepts: ASHBY's variety and MATURANA and VARELA's organizational closure.

Also unfortunately, the VS Model seems to be very difficult to assimilate for people who lack at least a global understanding of evolved cybernetic concepts, i. e. not merely WIENER's "Communication and control", or not even these! This leads easily to an "implementation syndrome" (p.442-3).