STABILITY
| Collection | International Encyclopedia of Systems and Cybernetics |
|---|---|
| Year | 2004 |
| Vol. (num.) | 2(2) |
| ID | ◀ 3141 ▶ |
| Object type | General information |
The ability of a system to maintain its equilibrium or regain it if temporarily perturbed.
With the exception pictured by a ball resting in the deepest of a well, stability is the result of a process. In effect, it depends necessarily on some cybernetic mechanism of stabilization.
In K. BOULDING words: “Stability has to be seen as a subspecies of change” (1956, p.68). It should never be confused with immobility.
Stability in systems is related to dynamic equilibrium and implies fluctuations of the systemic processes within defined limits, with the help of negative feedbacks to compensate excessive accelerations or amplitudes and positive feedbacks to compensate undue slowing down or reduced amplitudes. This is control by compensated or countervailing regulation.
- “Stable” is thus very far to mean “static”. As observed by E. JANTSCH, systems of high complexity trade part of their stability for richness in adaptability (1975, p.52).
A stable system is thus a controlled one — either naturally or artificially and in G. WEINBERG's words: “implies limits to the disturbances that the system is supposed to withstand” (1975, p.230). But the exact determination of this level of admissible disturbances is in itself a difficult and crucial matter (Ibid).
T.F.H. ALLEN and T.B. STARR explain: “There are several definitions involved:
- “a) Sensu lato, the general display of persistence in both structure and patterns of behavior. Here resilience is one aspect of stability.
- “b) Sensu stricto, specifically excludes resilience as part of the definition and refers only to the rapidity with which the equilibrium is restablished when displacement from the equilibrium occurs. Generally systems stable in this sense resist the influence of outside disturbance rather than accomodating the influence once it has had its effect.
- “c) Structural stability, the capacity of a system to display generally the same emergent behavior despite changes in the interrelationships between its parts. In case of an equation, structural stability would be represented by the persistence of general patterns of behavior despite changes in the equation parameters” (1982, p.278).
See also
instability, metastability, and ultrastability