Feedback is the process by which the outputs or behaviour of a system is fed back into the input to the system to affect succeeding outputs. Such feedback is termed negative when the work done by the feedback mechanism opposes the main driving force such as to dampen or eliminate it. Feedback is termed positive when the work done by the feedback mechanism reinforces the main driving force, so that in an oscillating system, for example, the fluctuations increase wildly until the system goes out of control. Amplification feedback occurs when the feedback is due in any measure to the exploitation of local energy.
Positive feedback (also known as schismogenesis) is a property of a wide range of systems ([eg] accumulation of capital in industry, evolution of living organisms, rise of certain types of culture, etc) and the processes that are loosely termed 'vicious circles' or 'vicious cycles', namely all processes of mutual causal relationships that amplify an insignificant or accidental initial impulse, build up deviation and diverge from the initial condition.