411 REFERENCE · Wiktionary
Ashby's law
Reference material by Wiktionary contributors. This retains its source identity and is not 411 news reporting.
English
Alternative forms
en Ashby's Law
en law of requisite variety
en law of requisite complexity
Etymology
Originally formulated by the cyberneticist W. Ross Ashby in 1956.Ashby, W. R. 1956, An Introduction to Cybernetics, Chapman & Hall, 1956, 0-416-68300-2 (also available in electronic form as a PDF from Principia Cybernetica)Ashby, W. R. 1958, Requisite Variety and its implications for the control of complex systems, Cybernetica (Namur) Vol. 1, No. 2, 1958.
Proper noun
To control variety externally, you must be able to control even more variety internally.
en https://www.edge.org/response-detail/27150 His "Law" of Requisite Variety stated that for a system to be stable, the number of states that its control mechanism is capable of attaining (its variety) must be greater than or equal to the number of states in the system being controlled. https://web.archive.org/web/20260925055254/https://www.edge.org/response-detail/27150 25 September 2026
References
en adages ending in "law" eponyms