Textbook of AI

1923–1969, Mathematical logician, cybernetician

Also known as: Walter Harry Pitts Jr.

Walter Pitts was a self-taught American logician whose collaboration with Warren McCulloch produced the foundational paper of mathematical neuroscience and of artificial neural networks. Pitts ran away from home in Detroit at the age of 15, having been beaten for being seen reading. He arrived at the University of Chicago, where without ever enrolling as a student he attended Bertrand Russell's lectures, was taken under the wing of the logician Rudolf Carnap (whose Logical Syntax of Language the teenage Pitts had spent three days reading and then critiqued in person), and met McCulloch.

The 1943 paper A Logical Calculus of the Ideas Immanent in Nervous Activity, written when Pitts was nineteen, modelled neurons as binary threshold units and proved that networks of such units could compute any propositional-logic expression. With Jerome Lettvin, Humberto Maturana and Warren McCulloch he later co-wrote the 1959 paper What the Frog's Eye Tells the Frog's Brain, identifying feature-detecting cells in the frog retina and inaugurating modern neurophysiology of vision.

Pitts's life ended tragically. A misunderstanding led Wiener, his closest mentor at MIT, to break with him entirely in 1952, and Pitts, devastated, burned his unfinished doctoral thesis on three-dimensional neural networks. He withdrew, drank heavily, and died of cirrhosis of the liver at the age of 46. McCulloch died four months later. The 1943 paper alone secured Pitts's place in the history of computing.