# Systems Theory

### From CasGroup

**Systems theory** is an interdisciplinary field which studies systems and their organization as a whole. It was founded by Ludwig von Bertalanffy, William Ross Ashby and others between the 1940s and the 1970s on principles from physics, biology and engineering and later grew into numerous fields including philosophy, sociology, organizational theory, management, psychotherapy (within family systems therapy) and economics among others. Cybernetics is a closely related field. In recent times complex systems has increasingly been used as a synonym. Examples of systems are organisms, organisations or societies.

## Development

All of the System "C"-Theories below - cybernetics, catastrophe theory, chaos theory,... - have the common goal to explain complex systems which consist of a large number of mutually interacting and interwoven parts. Steven Strogatz said in his book "Sync": "Every decade or so, a grandiose theory comes along, bearing similar aspirations and often brandishing an ominous-sounding C-name. In the 1960 it was cybernetics. In the '70s it was catastrophe theory. Then came chaos theory in the '80s and complexity theory in the '90s.".

- 1950 General Systems Theory (founded by Ludwig von Bertalanffy)
- 1960 cybernetics (W. Ross Ashby, Norbert Wiener) Mathematical theory of the communication and control of systems through regulatory feedback. Closely related: "control theory"
- 1970 catastrophe theory (RenĂ© Thom, E.C. Zeeman) Branch of mathematics that deals with bifurcations in dynamical systems, classifies phenomena characterized by sudden shifts in behavior arising from small changes in circumstances.
- 1980 chaos theory (David Ruelle, Edward Lorenz, Mitchell Feigenbaum, Steve Smale, James A. Yorke) Mathematical theory of nonlinear dynamical systems that describes bifurcations, strange attractors, and chaotic motions.
- 1990 complex adaptive systems (CAS) (John H. Holland, Murray Gell-Mann, Harold Morowitz, W. Brian Arthur,..) The "new" science of complexity which describes emergence, adaptation and self-organization was established mainly by researchers of the Santa Fe Institute (SFI) and is based on agents and computer simulations and includes multi-agent systems (MAS) which have become an important tool to study social and complex systems. CAS are still an active field of research.