What do we mean when we say that a system is "in control"?


What do we mean when we say that a system is "in control?" There are several important marks. Firstly, the output of the system (or the output that happens to be of interest to us) is held steady. We tend to watch this in practice by watching what happens to output if the system is disturbed in its peaceful running. Inevitably, the output is disturbed as well: but if the system is in control, the oscillation damps down. The best word for "being in control" in this sense is stability. If the system is unstable, then the disturbance of its smooth running may lead to violent oscillations in the output, which increase in magnitude after the cause of the disturbance has been withdrawn.

Secondly, we expect systems that are in control to maintain this kind of stability without our needing to take exception or panic measures to achieve the result. Constant surveillance and intervention ought not to be necessary.

So, and thirdly, we tend to judge whether such a system is in control by assesing its internal coherence, the smoothness of its operation. This is also a subjective judgement, but it turns out to have serious implications. The point is this: If people use this indirect criterion of smoothness as evidence of being in control, they may come to regard smoothness instead of in-control-ness as the object of the exercise, and this will make them resisitant to change.

For if cybernetics is the science of control, and if management might be described as the profession of control, there ought to be a topic called management cybernetics - and indeed there is. It is the activity that applies the finding of fundamental cybernetics to the domain of management control. (MS 143-144)


This page was last updated on August 5, 1996, by Rob Sable.