Ross Ashby

Law of Requisite Variety; Design for a Brain.

W. Ross Ashby (1903–1972) was a British psychiatrist who became a foundational theorist in cybernetics. His 1952 book 'Design for a Brain' modelled adaptive behaviour mathematically, and his 1956 'An Introduction to Cybernetics' introduced the Law of Requisite Variety — the principle that a controller must have at least as much variety as the system it regulates. His work underpins systems thinking, management cybernetics, and organisational design.