William Ross Ashby

William Ross Ashby (September 6, 1903, London - November 15, 1972) was an English psychiatrist and a pioneer in the study of complex systems. Despite being widely influential within cybernetics, systems theory and, more recently, complex systems, he is not nearly as well known as many of the notable scientists his work has influenced including Herbert Simon, Norbert Wiener, Ludwig von Bertalanffy, Stafford Beer and Stuart Kauffman.

Work
In May 1928, Ashby was 24 and a medical student at St Bartholomew's Hospital in London when he started recording his theories in a series of 25 notebooks. He wrote on average half a page a day for 44 years until shortly before he died. In January 2003 the notebooks, and an electronic copy, were donated to The British Library, London.

In 1946, Alan Turing wrote to Ashby suggesting he uses his ACE (Automatic Computing Engine) for his experiments instead of building a special machine. In 1948 Ashby made the Homeostat. Ashby only made one reference to Turing in his notebooks in December 1954.

Ashby's Law of Requisite Variety Variety absorbs Variety, defines the minimum number of states necessary for a controller to control a system of a given number of states. For example the number of bits necessary in a digital computer to produce a required description or model. In 1970 with Conant he produced the Good Regulator theorem "Every Good Regulator of a System must be a model of that System". Stafford Beer applied Variety to found management cybernetics and the Viable System Model. Working independently Gregory Chaitin followed this with Algorithmic information theory.

From 1947 to 1959, Ashby was director of research at Barnwood House Hospital in Gloucester. From 1959 to 1960 he was Director of the Burden Neurological Institute. From 1960 to 1970 in the Department of Electrical Engineering at the University of Illinois at Urbana-Champaign. Ashby became a fellow of the Royal College of Psychiatry in 1971.

Centenary conference
On March 4-6, 2004 a W.Ross Ashby centenary conference was held at the University of Illinois at Urbana-Champaign to mark the 100th anniversary of his berth. Presenters at the conference included Stuart Kauffman, Stephen Wolfram and George Klir.