International Encyclopedia of Systems and Cybernetics

2nd Edition, as published by Charles François 2004 Presented by the Bertalanffy Center for the Study of Systems Science Vienna for public access.


The International Encyclopedia of Systems and Cybernetics was first edited and published by the system scientist Charles François in 1997. The online version that is provided here was based on the 2nd edition in 2004. It was uploaded and gifted to the center by ASC president Michael Lissack in 2019; the BCSSS purchased the rights for the re-publication of this volume in 200?. In 2018, the original editor expressed his wish to pass on the stewardship over the maintenance and further development of the encyclopedia to the Bertalanffy Center. In the future, the BCSSS seeks to further develop the encyclopedia by open collaboration within the systems sciences. Until the center has found and been able to implement an adequate technical solution for this, the static website is made accessible for the benefit of public scholarship and education.



Condition of a system or process led by a fluctuation of a critical variable out of its homeostatic stability channel.

Dynamic stability's main characteristic is that the system oscillates periodically within defined limits of amplitude, without ever leaving the established fluctuations channel, or domain of attraction.

Instability, on the contrary is a runaway process with a finite time course, through a succesion of ever amplifying oscillations which lead the system closer and closer to the limits of its stability channel until a critical threshold is neared and the process undergoes a basic change. At that point the system reaches metastability and the slightest supplementary disturbance – even a small random "push" – turns it unstable, destroys it (the most common case for individual systems) or, rarely, shifts it toward a different form or organization.

Instability is closely related to environmental conditions, as stated by R. FIVAZ: "… instabilities have the property to bind conditionally the internal structure of the system to the value of an external field. This conditional bind is certainly a necessary ingredient to construct a complex system modelization inasmuch as such systems interact with the outside constantly, albeit selectively.

"In addition, real situations are characterized by unpredictable variations in the environment which submit systems to a succesion of independent and random fields" (1991, p.22).

The most significant perturbing influence for a system is a high increase of the rate of energy intake, which is the factor that leads it to giant fluctuations. In human systems, such increase is induced by the system itself (technical advances in the captation and uses of energy).

More recently, the boundaries of stability and instability have become quite blurred, through our new understanding of deterministic chaos. It becomes rather difficult in the case of a nonlinear system to know if it is inherently stable, metastable or unstable, since it may fluctuate wildly and frequently bifurcate, with the possibility that it may cross an instability threshold.

In some cases, the concept of instability should however be relativized. According to C. HOLLING, many systems have alternative dynamic stability conditions, within more global conditions of stability, as they may leap from one domain of attraction into another under the impact of some very strong and unusual perturbation. HOLLING writes: "… many examples for the influence of random events upon natural systems… suggest that instability, in the sense of large fluctuations, may introduce a resilience and a capacity to persist. They point out the very different view of the world that can be obtained if we concentrate on the boundaries to the domain of attraction rather than on equilibrium states. Although the equilibrium-centered view is analytically more tractable, it does not always provide a realistic understanding of the system's behavior" (1976, p.81).

In such cases, we could possibly speak of an endogenous ergodic instability. While unstable, the system at least keeps its identity.

An interesting comment by Y. SINAI connects instability with randomness: "The more unstable the movement, the more stable become the manifestations of randomness. The instability of a non-aleatory dynamics leads to the rise of randomness" (1992, p.87).


  • 1) General information
  • 2) Methodology or model
  • 3) Epistemology, ontology and semantics
  • 4) Human sciences
  • 5) Discipline oriented


Bertalanffy Center for the Study of Systems Science(2020).

To cite this page, please use the following information:

Bertalanffy Center for the Study of Systems Science (2020). Title of the entry. In Charles François (Ed.), International Encyclopedia of Systems and Cybernetics (2). Retrieved from www.systemspedia.org/[full/url]

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