Cybernetics

Circular causal processes in which a system's output is routed back as input, enabling self-regulation. Negative feedback reduces deviation from a goal (stabilizing), while positive feedback amplifies deviation (destabilizing or growth-promoting).

The capacity of a system to maintain its essential variables within viable limits through internal regulatory mechanisms, despite external disturbances. Originally described in physiology by Walter Cannon, it became a central cybernetic concept.

W. Ross Ashby's principle stating that a controller must have at least as much variety (number of possible states) as the system it seeks to regulate. Only variety can absorb variety.

A system whose internal workings are unknown or irrelevant to the observer; it is studied solely by examining the relationships between its inputs and outputs. This method allows analysis without requiring knowledge of internal mechanisms.

The principle that cause and effect are not linear but form closed loops, so that an effect feeds back to influence its own cause. This challenges simple linear cause-and-effect thinking.

The spontaneous emergence of order and pattern in a system through local interactions among its components, without external direction or centralized control. It is a key mechanism in complex adaptive systems.

A concept introduced by Maturana and Varela describing a system that continuously produces and maintains itself through its own internal processes. An autopoietic system defines its own boundary and regenerates its own components.

The cybernetics of observing systems, where the observer is recognized as part of the system being studied. Pioneered by Heinz von Foerster, it emphasizes that observation is never neutral and that models of systems always reflect the observer's framework.

In cybernetics, information is defined as a difference that makes a difference (Gregory Bateson) or as a reduction of uncertainty. It is closely related to thermodynamic entropy, since both measure disorder versus organization in a system.

The twin pillars of cybernetics as defined by Wiener. Control is the ability to steer a system toward a desired state, while communication is the transmission of information necessary for that steering. Together they describe how purposive behavior emerges in machines and organisms.