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The movie Forrest Gump made the point that the greatest, most heroic Americans are people of extraordinary character who flicker briefly into public consciousness and are quickly forgotten. Walter Pitts was pivotal in establishing the revolutionary notion of the brain as a computer, which was seminal in the development of computer design, cybernetics, artificial intelligence, and theoretical neuroscience. He was also a participant in a large number of key advances in 20th-century science. Yet while his contemporaries Alan Turing, Ludwig Wittgenstein, and John von Neumann entered the pantheon of fame, Pitts remains a shadowy folk hero. Stories about Pitts have circulated among the cognescenti for years, but almost nothing has been written about him. Here, I have collected reminiscences from his friends and associates to provide a unique insight into a remarkable life; if some exaggerations and embellishments have crept in, they only underscore the basic truth that Pitts was a man with Gumption.
Early Life (1923-1943)
Walter Harry Pitts, Jr., was born in Detroit on 23 April 1923, the son of Walter and Marie (née Welsia). His father and brothers were rough, uneducated characters who regarded Walter as a freak. At age 15 he ran away, [End Page 217] and from that time he refused to speak of his family. For the duration of his life he had no contact with them except for sending an anonymous Christmas present home each year. The story is told that, at age 12, Pitts ran into the public library to hide from some bullies, found a copy of Principia Mathematica by the 20th-century philosophers Bertrand Russell and Alfred North Whitehead, and proceeded to read it cover to cover in the next few weeks . Pitts experienced a metaphysical insight that logic rules the universe, and as a corollary he felt that ego--and his ego in particular--needed to be erased in order to achieve an understanding of the world. This insight, and his living up to it, was a cornerstone of his personality:
That is the peculiar truth about Pitts, whom all of us loved and protected. We never knew anything about his family or his feelings about us. He died mysterious, sad and remote, and not once did I find out, or even want to find out more about how he felt or what he hoped. To be interested in him as a person was to lose him as a friend. 
Seeking a place where a 15-year-old intellectual would not look out of place, Pitts arrived at the University of Chicago:
Walter was just 15 when he ran away from home, turned up in Chicago and there met a fellow who called himself Bert. Now, this Bert talked with Walter for some time of philosophy and mathematics, and came to realize that this was no ordinary youngster. Bert was impressed. He told the boy that Carnap, then Professor of Philosophy at the University of Chicago, had written a book that would interest him, and urged him to go and speak to the grand old man. So, Walter got himself a copy of Carnap's book and read it. Later, Carnap was to recount the meeting thus: "This young boy came in to see me and said he had read my book and that a certain paragraph on a certain page was not clear to him. Now when I say that something is not clear to me, I mean that that thing is nonsense. So we took down my copy of the book and opened it to the page in question and carefully read the paragraph . . . and it was not clear to me either!" 
Though the story of meeting "Bert" in this manner may be apocryphal, it is true that Pitts sat in on Bertrand Russell's course when the latter visited Chicago in 1938, and that he walked into Rudolf Carnap's office with a marked copy of his book filled with corrections and suggested improvements. After his initial contact...