Warren McCulloch

16 November 1898, Orange, New Jersey, United States – 24 September 1969, Cambridge, Massachusetts, United States (aged 70)

American neurophysiologist who, with Walter Pitts, wrote the 1943 paper that founded neural network theory. He chaired the Macy Conferences on cybernetics.

Life

McCulloch studied philosophy and psychology at Yale and medicine at Columbia, and worked as a psychiatrist and neurophysiologist in New York and New Haven before moving to Chicago in 1941. There he took in the teenage, homeless Walter Pitts, and the two began the collaboration that made them famous. In 1952 he moved to MIT’s Research Laboratory of Electronics, where his group included Pitts, Jerome Lettvin and, for a time, Humberto Maturana. He spent his summers at the family farm in Old Lyme, Connecticut, a frequent meeting place for his circle.

Influences

McCulloch set out as a young man to answer the question “What is a number, that a man may know it, and a man, that he may know a number?” The question came from his reading of philosophers and logicians from Leibniz to Peirce, and from the Quaker philosopher Rufus Jones. Pitts gave him the logical machinery to pursue it; Wiener and the wartime work on feedback gave him the language of circular causality.

Contributions

“A Logical Calculus of the Ideas Immanent in Nervous Activity” (1943, with Pitts) showed that networks of simplified on/off neurons can compute any logical function. It is the ancestor of every artificial neural network and influenced John von Neumann’s design for the stored-program computer.

As chair of the Macy Conferences from 1946 to 1953 he brought mathematicians, engineers, biologists and social scientists into one sustained conversation, which is where cybernetics took shape as a shared field. His later work with Lettvin, Maturana and Pitts on frog vision showed that the eye interprets as well as transmits, and he developed the idea of heterarchy, a circular ordering of values that no simple hierarchy can capture.

Why it matters today

Modern deep learning descends from the McCulloch–Pitts neuron, although the field kept the computation and dropped his questions about mind and meaning. His Macy chairmanship is also a model of something rare: specialists from many disciplines building a common language over years.

Further reading

  • Warren S. McCulloch, Embodiments of Mind (1965)
  • Tara Abraham, Rebel Genius: Warren S. McCulloch’s Transdisciplinary Life in Science (2016)

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