FEEDBACK (Positive)
| Collection | International Encyclopedia of Systems and Cybernetics |
|---|---|
| Year | 2004 |
| Vol. (num.) | 2(1) |
| ID | ◀ 1255 ▶ |
| Object type | General information, Methodology or model |
A feedback that accelerates or increases some process.
Positive feedback unavoidably is a disequilibrating phenomenon.
It implies an accelerated pumping of some specific resources from the environment by the system, generally feeding a runaway growth which finally escapes from any possible control.
Such a situation leads normally and swiftly towards the exhaust of the critical resource and, consequently to the collapse, or even destruction of the system.
One may give as examples: a nuclear or chemical explosion; the inordinate growth of a population; a runaway bull or bear market (mind the 1929 and 1987 crashes); a fire; a cancer.
Fortunately, but possibly somewhat optimistically in some cases, in J.H MILSUM's words: “Upper and lower constraints always exist in real systems which prevent true runaway” (1968, p.39). A good knowledge of these constraints, — in many cases located in the metasystem — and their proper use, is very useful in maintaining the stability of a system. On the contrary, unawareness of their existence may lead to their unwitty removal, triggering the runaway process.
For practical purposes, feedbacks, natural or introduced, specially positive ones, should always be closely monitored, in order to avoid unforeseen and unwanted quantitative effects, leading ultimateluy to qualitative ones.
Positive feedbacks can be controlled, but only a priori, by well conceived design, not a posteriori.