Jason Hatfield, Spring 2024
In 1952, Alan Turing, mathematician, codebreaker, and creator of the field of artificial intelligence, was convicted of gross indecency and had his security clearance revoked. At the time, gross indecency was the British government's code for homosexual relations, which he had engaged in with a younger man. Instead of facing prison time, he chose probation, which included being chemically castrated. It is impossible to acknowledge the full breadth of Turing’s impact without acknowledging his homosexuality, and the reprehensible act of requiring him to be chemically castrated for acting on it. This project examines his impact on the early history of computer science, including artificial intelligence and the Turing machine, a fundamental building block in all modern computers.
Turing's work in computing is bookended by two papers: 1936's "On Computable Numbers" and 1950's "Computing Machinery and Intelligence". Both represented large steps in computing and created concepts that are named after him. "On computable numbers" dealt specifically with David Hilbert's Entscheidungsproblem, the question of whether any arbitrary statement can be proven using the rules of logic. To prove that the answer to that question is no, he proposed a machine that could compute any algorithm. This would later become known as a Turing machine, which evolved into the stored-program computing architecture laid out by John von Neumann in his "First Draft of a Report on the EDVAC", which is used by all computers today. The Entscheidungsproblem would be later extrapolated into the effectively equivalent "halting problem", which proved that it is impossible to determine whether any given algorithm will loop forever or halt.
In 1938, after earning his PhD at Princeton University (his thesis introducing the concept of ordinal logic), Turing began to work with the UK's Government Code and Cypher School on cryptanalysis of Germany's Enigma cipher mechanism. After World War II broke out the next year, Turing transferred to Bletchley Park fifty miles outside of London, which would be his and GC&CS' home for the next six years. It was there that his team at Hut 8, among others, worked full-time on breaking the Axis' codes, which were most commonly encrypted using the Enigma machine. Polish cryptanalysts had already broken Enigma in 1932, but as it advanced, it became harder to break. Hut 8's team was focused specifically on naval communications, but Turing personally designed the Bombe, a machine used to speed up the analysis of Enigma messages in general. In 1941, he got engaged to Joan Clarke but admitted to her that he was homosexual and broke off the engagement later that year. His probabilistic cryptanalysis, Banburismus, would later be used in the development of the Colossus computer, as well as his method to break the later Lorenz cipher. It's impossible to fully know the impact of Bletchley Park's codebreaking, but it's likely that it shortened the war by multiple years and saved millions of lives.
After the war, Turing worked with the National Physical Laboratory on the design of a stored-program computer, called the Automatic Computing Engine, harkening back to the work of Charles Babbage. As originally presented, the ACE would have been feasible. However, he was working off of the Colossus design, which was still secret, so he could not explain how it was feasible. Instead, after Turing left NPL in 1947, a team there created the Pilot ACE, a simpler design that ran its first program in 1950. Also in 1950, while working at the University of Manchester, Turing published the paper "Computing Machinery and Intelligence", which asked the question "Can machines think?" and proposed a test to determine that. He believed that if a machine was sufficiently indistinguishable from a human in a natural-language conversation, what he called the "imitation game", then the answer would be yes. This is now known as the Turing test, which sparked the field of artificial intelligence as we know it today.
On June 8, 1954, Alan Turing was found dead of cyanide poisoning in his home in Wilmslow. He was forty-one years old. Thoughts differ on the circumstances of his death; the theory supported by the coroner's inquest was that he had killed himself, recreating the scene in Snow White and the Seven Dwarfs where Snow White "ate a poisoned apple, dipped in the witches' brew" (Hodges 1983). The evidence doesn't fully support that, though. By all accounts, Turing was in good spirits at the time and had even made plans for the coming days. Instead, it's been suggested that his death was an accident, resulting from his experiments in electroplating spoons, and he didn't realize he had inhaled cyanide until it was too late (Pease 2012). There are even those who suggest he was murdered by forces unknown.
No matter the circumstances of his death, a few things are for certain: Turing's work on the Enigma with GC&CS helped shorten World War II, his work on artificial intelligence sparked a field that's expanding by the minute, even now, and he died without knowing he would be recognized as both a gay icon and an icon in the computing world. It wasn't until 1974, twenty years after his death, that Frederick Winterboatham would be allowed to publish The Ultra Secret, exposing the world to the codebreaking activities at Bletchley Park. In December 2013, after two online petitions, each with thousands of signatures, and an official apology from Prime Minister Gordon Brown on behalf of the British government, Turing's gross indecency conviction was pardoned, and a royal decree solidified it the following August (BBC 2013, Mullen 2014). Turing is rightfully revered as an early icon in computing, despite his marginalization. All that's left to say is, thank you, Alan, for everything.
Bibliography
BBC. 2013. “Royal Pardon for Codebreaker Turing.” BBC News, December 24, 2013, sec. Technology. https://www.bbc.com/news/technology-25495315.
Bird, Charles, Leonard Cottrell, George Gibson, Eliza Clayton, John Turing, and Ronald Leigh. 1954. “TS Copies of Depositions Made at Inquest on AMT and Cyclostyled Copy of Post-Mortem Examination Report on AMT.” The Turing Digital Archive. June 8, 1954. https://turingarchive.kings.cam.ac.uk/material-given-kings-college-cambridge-1960-amtk/amt-k-6.
Hodges, Andrew. 1983. Alan Turing: The Enigma. Princeton, N.J.: Princeton University Press.
Mullen, Jethro. 2014. “Alan Turing, Code-Breaker Castrated for Homosexuality, Receives Royal Pardon.” CNN. August 19, 2014. https://www.cnn.com/2013/12/24/world/europe/alan-turing-royal-pardon/index.html.
Neumann, John von. 1993. “First Draft of a Report on the EDVAC.” IEEE Annals of the History of Computing 15 (4): 27–75. https://doi.org/10.1109/85.238389.
Pease, Roland. 2012. “Alan Turing: Inquest’s Suicide Verdict ‘Not Supportable.’” BBC News, June 26, 2012. https://www.bbc.com/news/science-environment-18561092.
Turing, Alan. 1950. “Computing Machinery and Intelligence.” Mind LIX (236): 433–60. https://doi.org/10.1093/mind/lix.236.433.
———. 2004. The Essential Turing: Seminal Writings in Computing, Logic, Philosophy, Artificial Intelligence, and Artificial Life plus the Secrets of Enigma. Edited by B. Jack Copeland. Oxford ; New York: Oxford University Press.
Winterbotham, Frederick. 1974. The Ultra Secret. London: Harper & Row.
Acknowledgments
Special thanks to all current owners of items consulted for this project, including Bletchley Park Trust, Science Museum Group, National Portrait Gallery, and King's College, Cambridge.
This study abroad research project is supported by funding from the University of Alabama in Huntsville Honors College.
