Systems Thinking: On The Law of Requisite Variety (Quotes)

"Only variety can destroy variety." (W Ross Ashby, "An Introduction to Cybernetics", 1956)

"The Law of Requisite Variety enables us to apply a measure to regulation." (W Ross Ashby, "An Introduction to Cybernetics", 1956)

"For any system the environment is always more complex than the system itself. No system can maintain itself by means of a point-for-point correlation with its environment, i.e., can summon enough 'requisite variety' to match its environment. So each one has to reduce environmental complexity - primarily by restricting the environment itself and perceiving it in a categorically preformed way. On the other hand, the difference of system and environment is a prerequisite for the reduction of complexity because reduction can be performed only within the system, both for the system itself and its environment." (Thomas Luckmann & Niklas Luhmann, "The Differentiation of Society", 1977)

"Another implication of the Law of Requisite Variety is that the member of a system that has the most flexibility also tends to be the catalytic member of that system. This is a significant principle for leadership in particular. The ability to be flexible and sensitive to variation is important in terms of managing the system itself." (Robert B Dilts, "Modeling with NLP", 1998)

"[...] the Law of Requisite Variety states that "in order to successfully adapt and survive, a member of a system needs a certain minimum amount of flexibility, and that flexibility has to be proportional to the potential variation or the uncertainty in the rest of the system'. In other words, if someone is committed to accomplishing a certain goal, he or she needs to have a number of possible ways to reach it. The number of options required to be certain the goal can be reached depends on the amount of change that is possible within the system in which one is attempting to achieve the goal." (Robert B Dilts, "Modeling with NLP", 1998)

"'Law of Requisite Variety' [...] states that if a problem is to be solved, the variety of the response must be equal to or greater than the variety of the problem, that is the complexity of a response must at least match the complexity of the problem. The line where contextual complexity equals complexity of organisational response, the 'Line of Requisite Variety', represents an optimal match between the complexity of a given problem and that of the response." (Bettina von Stamm, "Managing Innovation, Design and Creativity", 2003)

"The control system theory deals with the concept of law of requisite variety. The law of requisite variety is based on rigid and complex algorithms and formulations. The law of requisite variety states that in a control system, the number of control variations should be equivalent to the number of possible loss of control points. In real world control systems that operate in business organizations, one to one control does not become practical." (S R Singh, "Information System Management", 2007)

"The notion of feedback to regulate servomechanisms is the control engineer’s contribution to understanding how systems can be sensed, and then sufficient sense made of this for the purpose of having the system behave agreeably. The cleverness of control has been to influence systems behavior when a priori knowledge of that system is difficult or impossible to achieve. Usually you need to know what it is you are controlling to have a chance of regulating its behavior; that is one consequence of the law of requisite variety." (John Boardman & Brian Sauser, "Systems Thinking: Coping with 21st Century Problems", 2008)

"Two systems concepts lie at the disposal of the architect to reflect the beauty of harmony: parsimony and variety. The law of parsimony states that given several explanations of a specific phenomenon, the simplest is probably the best. […] On the other hand, the law of requisite variety states that for a system to survive in its environment the variety of choice that the system is able to make must equal or exceed the variety of influences that the environment can impose on the system." (John Boardman & Brian Sauser, "Systems Thinking: Coping with 21st Century Problems", 2008)

"The principle of requisite variety means essentially that if you want to cope successfully with a wide variety of inputs, you need a wide variety of responses. If you have less variety than your inputs, the system could be destroyed." (Karl E Weick et al, "Managing the Unexpected: Resilient Performance in an Age of Uncertainty", 2011)