Episode 28: Alan Turing

Hi everyone!

As part of Pride month, I’m so excited to bring you the story of Alan Turing! Enjoy!

🎙️ Transcript

Hey everyone, welcome to Unruly Figures, the podcast that celebrates history’s greatest rule-breakers. I’m your host, Valorie Clark, and today I’m going to be covering a man whose work literally changed the world: Alan Turing. He’s remembered as the Father of AI and for his work breaking the German codes during World War II. But he was a prolific genius, whose interests extended beyond early computing. 

But before we jump into Turing’s life and how he helped bring computers to life, I want to give a huge thank you to all the paying subscribers on Substack who make this podcast possible. Y’all are the best and this podcast wouldn’t still be going without you! Each of these episodes takes me nearly 30 hours of work, which means they’ve become a part-time job. So if you like this show and want more of it, please become a paying subscriber for just $6/month or $60/year! Contributions help ensure that I will be able to continue doing this work. Becoming a paying subscriber will also give you access to exclusive content, merch, and behind-the-scenes updates on the upcoming Unruly Figures book. When you’re ready to do that, head over to unrulyfigures.substack.com. 

Okay, let’s hop in.

Alan Mathison Turing was born on June 23, 1912, in London, at the Colonnade Hotel near Paddington Station. His family was upper middle class; his father, Julius, was part of the Indian Civil Service, serving the Madras Presidency, which covered most of Southern British India. His mother, Ethel Sara Stoney–better remembered as Sara–was the daughter of an engineer involved in the railways. His parents met in India but married in Dublin; this was the start of a lot of back-and-forth travel for the couple. It seems like both Turing and his older brother, John Ferrier, were born in England despite the couple living in India. 

Alan and John lived in luxury but also practically as orphans–both boys were hosted by other families and adults while their parents continued to work in India. For many years, they rarely saw their parents. In her biography of her son, Sara Turing remembers that he went through a change in his early childhood. Quote, “From having always been extremely vivacious–even mercurial–making friends with everyone, he had become unsociable and dreamy.”¹

Alan Turing as a schoolboy. Source.

During his childhood, Alan made up a game called round-the-garden-chess.² It was a version of chess–after making a move, a player had to run around their home while the other player made their move. If the second player didn’t make their move by the time the running player made it back to the game, they forfeit their move and had to run while the first player made a second move in a row. This is not a game I would ever play, because I hate to run, but I love this story. Alan would continue to love both chess and running for the rest of his life. 

At 9 years old, Alan was sent to boarding school at Hazelhurst, a prep school for upper class boys. Reports are mixed, but it seems like he might have been bullied at Hazelhurst. There’s a drawing that Alan’s mother Sara made of him at this age; the boys around him are playing field hockey and Alan is studying a daisy. It’s really sweet. I’ve included it in the transcript.

“Hockey, or Watching the Daisies Grow” Sara Turing, 1923

Five years later, when he was 14, he moved onto the Sherborne School in Dorset, where his older brother John had recommended to their parents that Alan be sent. John was at Marlborough College, which he found, quote, “thoroughly miserable” and concluded that young Alan would, quote, “wither in that environment.”³ Sherborne School was more liberal and would indulge young Alan’s passion for science, which John believed would fit him more than Marlborough. 

Legend has it that Turing arrived at Sherborne alone on his bicycle, disheveled from biking more than 60 miles and without any luggage. He apparently rode right up to the headmaster or someone and announced, “I am Turing.” 

Around this time, his father retired from his government position in India and Turing’s parents moved back to England. When they came back, they found that Turing had immersed himself completely in math and science, and they were concerned that he wasn’t getting a good liberal arts education. So his father assigned him reading, mostly Shakespeare, but Turing apparently hated all of these except one–Hamlet. His parents were excited until Turing said that the only line he liked was the last one: “Exeunt, bearing off the dead bodies.”⁴

In 1926 or so, Turing made friends with Christopher Morcom. The two became practically inseparable. They shared an interest in advanced mathematics. While the other boys wanted to go to pubs or play sports, Turing and Morcom would stay behind to play chess or visit the observatory.⁵ Morcom was one of the first people that Turing could be entirely himself with. Not only did they get along really well, but Morcom was also smart enough to keep up with Turing. They talked about math, chemistry, and astronomy–the last seems to be one of Morcom’s great interests. They performed experiments together, and exchanged letters comparing their results when they were apart between semesters. By his mid-teens, Turing had already developed idiosyncratic methods of mathematical notation which no one else could make heads or tails of. He also had truly awful handwriting, which many of his teachers complained about; one called it “the worst I have ever seen.”⁶ But Morcom could and didn’t give Turing a hard time about it. In one biography I read, The Imitation Game: Alan Turing Decoded, Morcom is depicted as almost a filter and compass north for Turing, helping him figure out when he had to quote-unquote “act normally” for the benefit of less-intelligent people. For instance, while taking their entrance exams for university, Morcom apparently reminded Turing that he had to use “standard notation” for the math test, not his own notation.⁷

Turing would tell his mother that the best week of his life began on December 9, 1929. He went to visit Christopher Morcom at Cambridge and to sit the entrance exams. Morcom was a year older and was already attending Trinity College. Morcom showed Turing around, telling him about Cambridge life and introducing him to scholars that Morcom had already begun working with. 

Christopher Collan Morcom, 1911-1930

However, in February 1930, tragedy struck. Christopher Morcom died suddenly of tuberculosis. Turing was devastated by this young death, though he’d had a strange premonition of it. According to him, at 2:45 am one morning in January 1930, a ringing abbey bell woke Turing and drew him to his dormitory window, where he looked at the moon and believed it was giving him a sign to say goodbye to Morcom.⁸ Christopher was dead a week later. 

The two had been excited to be college students together; suddenly that dream was robbed from Turing. Some people consider Morcom to be Turing’s first great love. Certainly their relationship was significant for Turing, and he grieved Morcom’s death for a long time. The ideas and plans they made during their friendship served as Turing’s inspiration for his work for the rest of his life. Turing also remained close to Morcom’s parents, often visiting and writing to them, especially in the first few years after Morcom’s death. Together they established an educational prize; the winner could pick from Morcom’s incredible cache of advanced mathematics and science books.⁹ Turing won the prize twice, and apparently kept the books from Morcom’s personal library for the rest of his life.¹⁰

Morcom’s death excited Turing’s curiosity about consciousness. He began to wonder what happens to consciousness after death, and if it could be replicated or preserved beyond the body. I think these are pretty normal things to think about while grieving, but Turing had the mathematical genius to actually explore some of these concepts! His earliest forays into fields that today we call Artificial Intelligence and an be seen as a result of this curiosity. 

Two years later, while on a visit to Christopher’s family home, Turing wrote an essay titled “Nature of spirit.” In it, he wrote, quote, 

We have a will which is able to determine the action of the atoms probably in a small portion of the brain, or possibly all over it. The rest of the body acts so as to amplify this. There is now the question which must be answered as to how the action of the other atoms in the universe are regulated. Probably by the same law and simply by the remote effects of spirit but since they have no amplifying apparatus they seem to be regulated by pure chance. The apparent non-predestination of physics is almost a combination of chances…Matter is meaningless in the absence of spirit.¹¹

The idea that some sort of ‘spirit’ acted as “cosmic gasoline” was popular at Cambridge in the early 1930s. Some people see this popularity of cosmic–almost paranormal explanations–as a crisis of science. Scientists had come so far in accounting for how the universe operated, but were searching for some sort of foundational unifying mechanism outside of the concept of an almighty deity.   

Turing would sort of always hold onto this idea. He always felt that there was something more, some sort of force that was sort of determining how atoms ordered themselves, and he was searching for it pretty early. Twenty years later, these ideas would come together in his biological and artificial intelligence studies. 

But that is all still to come. For now, we’re in 1931 and Turing is going to King’s College, Cambridge to study math, or maths as the Brits call it, on a research scholarship. There he studies mathematics, plays bridge and tennis, rows, goes to the theatre, plays the violin, and immerses himself in the local gay culture. He wrote home, and his letters show, quote, “a vibrant interest in the anti-war movement.”¹²

One of the most interesting things about Turing, I think, is that it seems like he never tried to hide his sexuality. He was very comfortable with who he was from a very young age, and was open about it. In the 1930s and 1940s this was an incredibly brave way to live because homosexuality was still illegal in the UK. But he never hid it. 

Turing in the early 1930s.

In 1934, Turing passed his final exams at Cambridge with flying colors. The next year he was elected a Fellow of King’s College at the astonishingly young age of just 22. This was awarded to him as recognition for his work in probability theory.¹³ The same year, he attended Max Newman’s lecture series on the foundations of mathematics. Newman would end up being a huge influence on Turing’s life and work, and their paths intertwine several times from here. Newman’s lecture series inspired Turing to invent the universal Turing machine. 

In 1936, Turing proposed the universal Turing machine, a device that could, quote, “represent the mechanization of mathematical processes.”¹⁴ He wanted to show, more or less, not what could be mechanized but what could not be. In 1931, mathematician Kurt Gödel had put forth a theorem that showed that there were limits to what could be proved in mathematics and that, importantly, there would always be an element of unpredictability and even chaos. It was called the incompleteness theorem. This shocked and even angered mathematicians of the age–maybe Kurt Gödel deserves his own episode, if I can ever figure out how to correctly pronounce his name!¹⁵

Kurt Gödel in the late 1920s.

But it didn’t upset Turing. In fact, building on Gödel’s theorem, Turing wanted to understand the boundaries of the systems of mathematics–if I’m understanding correctly, he was trying to delineate what could be proved what couldn’t be. These questions are the theoretical foundation of mathematics. It was in seeking to prove these ideas that Turing first proposed a machine that could help prove that there are “mathematical realms that, in a certain sense, lie beyond the range of any computer, no matter how powerful.”¹⁶

Turing’s theoretical machine would be programmed to emulate any other machine. The idea was that it would be able to perform every possible computation.¹⁷  It was the first ever ‘stored-program’ concept, and he envisioned as, quote, “a single slab of hardware that could change seamlessly from a machine dedicated to one type of work into a machine dedicated to a completely different job.”¹⁸

It did this through sequences of coded instructions, what today we call programs. He called it his “universal computing machine” but today we call it the universal Turing machine. This is sort of the introduction of universal computation, which would become the foundation of modern computer science. He wanted to build it right away, but the technology just didn’t exist in 1936. In proving that there were machines that could solve any known computation, Turing also showed that it is, quote, “definitely not the case that all well-defined mathematical tasks can be done by computer–not even in principle. Some tasks simply cannot be performed by computing machines, no matter how good the programmers or how powerful the hardware. Turing was the first to describe examples of tasks like this, and in discovering them he blazed a trail through…the unknown world of uncomputability.”¹⁹ Now I’m going to be really honest–I do not understand Turing’s work well enough to go much deeper into it. And I’ve tried. But if you are interested in the theory and science Turing was putting forward, there is so much out there for you. Take a little google of his work. 

The next year, Turing traveled to the US to study for his PhD under the direction of Alonzo Church at Princeton. He was studying mathematical logic. He stayed in the US for two years, which was, incredibly to me, enough time for him to finish his PhD and return to England on the eve of World War II as a fully accredited doctor. It’s hard for me to tell what the course of events were, but it seems like Turing might have come to Church’s attention because the two mathematicians were reaching the same conclusions at the same time. Before starting his PhD, Turing published his famous paper “On Computable Numbers, with an Application to the Entscheidungsproblem,” which laid the foundation for modern computer science. Church had reached the same conclusions at Turing, albeit by a different method, and the result was that their student-advisor relationship got started on something of a strange foot.²⁰

To be clear, Church had actually recommended that Turing’s paper be published, but still–it seems like the student was surpassing the master before they’d even really gotten started. 

While at Princeton, Turing began studying mathematical intuition for his PhD thesis. I’m not going to get too deep into this, but the concept is not too difficult to understand. Basically, it studies how math equations or puzzles can be intuited as true without taking the time to actually solve them or develop proofs. For instance, we all know that 1 + 1 = 2, we don’t need proof of it. When anyone with minimal math training sees that equation, we know it to be true. Mathematical intuition, also called logical intuition, extrapolates from there, basically saying that the more training one has in math, the more difficult equations one can intuit the answers to without needing proofs.²¹

His PhD thesis, when finished, was called “System of Logic Based on Ordinals.” If you’re interested, this thesis can be readily found online. It basically argues that the need for mathematical intuition is boundless. Much like his earlier work supporting Gödel’s theorem of incompleteness, Turing was arguing against old quests for complete certainty in mathematics.   

Turing returned to the UK and Cambridge as it became clear that war with Germany was inevitable. He remained at Cambridge during the tense early months of 1939, giving lectures on mathematical logic and attending courses on the foundations of math taught by, quote, “eccentric” Cambridge philosopher Lugwig Wittgenstein.²² It sounds like Turing and Wittgenstein didn’t really see eye to eye; at least Turing described other classes he took at the Government Code and Cypher School (GC&CS) to be “more useful, applied courses.”²³ The GC&CS had grown out of the intelligence network of WWI and was still operating in peacetime in London. 

Turing was invited to take courses there probably based on the electrical cipher machine he’d built while at Princeton, as if he hadn’t had enough on his plate. The courses focused mostly on linguistics and puzzle-solving–math and algorithms weren’t really the focus yet. But he excelled there, so it’s hardly surprising that his name was put down on a list of potential code-breakers for the future. A man named Alastair Deniston was in charge of the GC&CS at the time, and his plan was to have a quote, “emergency list of ‘men of the professor type’” who could be called on to break codes should war break out again.²⁴

When war was declared on September 3, 1939, Turing reported straight to GC&CS. Headquarters had been moved out of London to the now-famous Bletchley Park, an old Victorian Manor northwest of London. It was known then as Station X. He worked under veteran codebreaker Dilly Knox in his research section. There were dozens of people working there already–a lot of math and logic people, but also a lot of linguists. 

Just twenty-seven-years-old at this point, Turing began the work that he is probably best known for today: Attempting to crack the German Enigma machines. The machines were used to encipher messages that were transmitted between Hitler’s army, and they were pretty complex. Some pen and paper methods were being developed, but they were much too slow to keep up with the sheer volume of messages being sent every day. A quicker method was necessary, and that’s where Turing came in. 

Let’s talk a little about the Enigma machine. It was first designed by a German engineer named Arthur Scherbius and developed for commercial use in the 1920s by Chiffrienmaschinen AG, a German company. It was designed for banks who needed to transmit sensitive information without compromising anyone’s personal security. Several governments took notice and bought some in order to study them. 

In the most basic description, Enigma worked by carrying out a letter-for-letter substitution of German text. It had a typewriter keyboard which anyone who wrote German could type on, and then a second copy of the keyboard above, which would light up to indicate the ciphered letter. The machine would then encipher the message by substituting each letter typed with another letter, which was decided by a series of three wheels inscribed with letters. For instance, a typist could press the U key, the wheels would rotate, and then the letter D would light up, signaling that the letter D was the encryption of U at that point in the message. Which letter encrypted another could change throughout the message, so D didn’t always stand in for U. However, a letter could never be encoded as itself, which was a major flaw in the design. 

Importantly, Enigma was what we’d call an offline machine today. It couldn’t actually transmit messages, it could only create cyphers. Instead, a “complicated programme of changing [radio] frequencies was used during transmission” of messages.²⁵

Naturally, Poland took notice when the German government started supplying their military with hundreds of Enigma machines in the early-1930s. Polish codebreakers immediately tried to start cracking the German code. This is your usual espionage stuff, you know, but it came in very handy. Several Polish codebreakers escaped Poland by the skin of their teeth when Germany invaded in 1939. Most important of these was probably Marian Rejewski, who gave what he knew about breaking the German codes to the English government, which is how Bletchley Park got started. 

At Bletchley Park, Turing began working on his Enigma-breaking machines, which he called the ‘bombe,’ spelled B-O-M-B-E. It was based on the Polish bombas, which were trying to perform the same tasks. In 1940, Turing actually traveled to Paris, where the Polish government-in-exile was operating from. He was present when Polish codebreakers decrypted the first Enigma message to be broken since the start of the war. 

Meanwhile, there was a very real fear of a German ground invasion into the UK. In addition to his work at Bletchley, Turing joined the Home Guard, a group of soldiers who would stay home to protect the country in the event that there was an invasion. There is actually an incredibly funny story related to this that I think demonstrates how clever Turing was, in addition to being just a mathematical genius. 

So, when people signed for the Home Guard, there were of course papers they had to sign, with lots of contract clauses to agree to. Most of them were framed as yes/no questions, and enrollees had to say ‘yes’ to every question in order to actually join up. One of the questions, was, quote,  “Do you understand that, by enrolling in His Majesty’s Local Defence Volunteer, you render yourself liable for military discipline?”²⁶ He answered no–and argued, quote, “I can imagine no set of circumstances under which it would be to my advantage to answer this question ‘Yes’.”²⁷ He knew that technically this would disqualify him, but he also equally knew that no one was actually reading these. It was wartime, they were busy!

Turing began training with his squadron and became a first-class shot. But as the threat of German ground invasion went down and his work at Bletchley became demanding, Turing stopped showing up for his Home Guard duties. After several weeks of this, he was court-martialed, and had to appear before Colonel Fillingham, Officer Commanding the Buckinghamshire Division of the Home Guard. Fillingham was angry and blustering about the whole thing–he asked Turing if he realized that missing his duties was a serious offense, and Turing said, “No sir.” Fillingham asked, quote, “Private Turing, are you trying to make a fool out of me?”²⁸ Well of course Turing said, quote, “No, sir, but if you look up my application for admission to the Home Guard, you will see that I do not understand that I am subject to military discipline.”²⁹ His signing papers were fetched and sure enough there it was in black and white. He was kicked out of the Home Guard, his entire enrollment considered null and void. Which he was fine with, he had bigger fish to fry. 

Around this time, Turing became especially focused on breaking Germany’s Naval Enigmas, which were slightly different from the Luftwaffe’s Enigmas and the Army’s Enigmas. The original Enigma boxes came with five cypher wheels, and operators chose three for their messages. But the navy’s were upgraded to have eight options for cypher wheels, meaning there were more possibilities for encryption, which made decryption that much more complex. Breaking all of these enciphered messages was important, but the naval ones were especially so because England was quickly losing the war of the Atlantic. 

In June 1941, Winston Churchill’s advisors were, quote, “warning him that the wholesale sinkings in the North Atlantic would soon tip Britain into defeat by starvation.”³⁰ The UK is a small island and for a very long time they’ve had to import at least some of their food supply; during the war, Germany used U-boats to bomb ships carrying food and other supplies into the UK, causing shortages and spreading panic. Churchill would later confess, quote, “The only thing that ever really frightened me during the war was the U-boat peril.”³¹

People became increasingly desperate to try to crack the Naval Enigma. Some military advisors started suggesting that serious effort should be put into the Royal Navy capturing a German’s codebook. Admiral John Henry Godfrey, officer of the Royal Navy, began plotting with people at Bletchley Park. But it was his assistant who put forward the most audacious scheme yet. He suggested that they crash a captured German bomber in the English Channel, close to a German vessel. They would disguise RAF airmen in German uniforms and have them radio for help from the German boat. When the sailors rescued the crew, the RAF men would kill their quote-unquote “rescuers” and steal whatever Enigma materials they could find.³² Does it surprise you to learn that this assistant to Admiral Godfrey was none other than Ian Fleming, author of the James Bond novels? 

Operation Ruthless, as Fleming’s plan was called, was postponed and eventually canceled.³³ In March 1941, however, the Royal Navy’s HMS Somali captured Enigma documents and several wheels from the German trawler Krebs. These assisted the folks at Bletchley in their codebreaking work. 

To break the Naval Enigma, Turing holed up in a cottage away from the administrators inside the Bletchley Park mansion. He used a loft that was difficult to access, so two of the women who were assisting him in his work created a pulley and basket system to send him food and coffee.³⁴ When he finally figured out how to do it, he sent down a treatise on Enigma and using what they called cribs to crack it down in the basket.

Turing’s bombes finally broke the U-boat transmissions in 1941. The messages revealed each boat’s position, which gave ships crossing the Atlantic an easy means of simply avoiding the U-boats. Soon, Bletchley Park was able to read U-boat messages almost as quickly as the Germans were. Turing was summoned to Whitehall for an official congratulations and a £200 bonus. That’s about £8,000 today. 

Estimates of what would have happened had Turing’s machines never broken the Enigma cypher vary. Many say he ended the war at least two years earlier than it might have otherwise, saving millions of lives. But some suggest that there was a real chance of the Allied powers not winning the war without this. As I mentioned, the naval blockades of the Atlantic were devastating both in terms of food supply and morale; it’s hard to say how much longer things could have gone on if the Naval Enigmas had been able to continue operating unimpeded. Many more ships with supplies, troops, and civilians could have been sunk.   

I also want to note that the Enigmas were incredibly well-designed machines. I don’t want to discount the hard work of Turing and all the people he worked with, but there’s a good chance that if the German military had just used the machines properly, the codes might never have been broken. Human error is what the codebreakers relied on to break the German codes. There were four main ways this worked: 

1. What they called Cribbing: German messages tended to repeat key words and phrases like ‘weather’ or ‘station’ or various greetings and signoffs. Codebreakers learned to recognize where in each transmission those repeated phrases would come up and they would use that as their starting point to break each day’s code. 

2. The wheels that encoded messages weren’t changed daily, which they were supposed to be. The German airforce and army actually tended to only change their wheels once a week, while the navy was changing theirs every few days. So once a code was cracked, it was cracked for at least a couple of days, which really reduced the British codebreakers’ work. Also, though there were eight wheels available, only a few were used at a time. When they were changed out, they were supposed to use a random combination of wheels, but the encrypters often used certain wheels over and over again, which also made the code easier to crack.  

3. The code encrypters would add notes to the bottom of their messages saying what settings needed to be put on the Enigma to decode the message. Which seems dumb said like that; this part was encrypted, but once the code breakers learned where in the message that key appeared and how to read that, it became much simpler to break the code. 

4. The German military used the Enigma machine way too much. As early as 1943, Turing’s team was cracking a, quote, “staggering total of 84,000 Enigma messages each month–two messages every minute.”³⁵ The Germans used the Enigma machines for everything, even things that weren’t really necessary to encode, like complaints about uniforms. But as anyone who loves logic puzzles can tell you, more information makes the puzzle easier. Think about sudoku–the more numbers you have to start with, the easier it is to fill in the other numbers, right? So the military was using Enigma for every communication, which gave codebreakers tons of material to work with, so it was easier to find patterns. 

So that was what was being used to fight the Enigma machines. It wasn’t all brute computing force, there was a lot of logic being applied to decoding German messages. There is, of course, so much more to this, so if you want more information I recommend checking out The Turing Guide, which contains several chapters dedicated to the Enigma machine and how the codebreakers broke it. 

During this time, many of the people working with Turing at Bletchley Park were women. They were titled linguists, though they did the codebreaking work much the same as the other cryptanalysts did. Turing was apparently troubled that the women were doing similar work as the male cryptanalysts but usually were receiving neither that title and certainly not that salary.³⁶

Joan Clarke in the late 1930s; this is her service photo.

One woman who he worked with, Joan Clarke, Turing became very close to. In 1941, Turing proposed to her, and the two went on a vacation to celebrate their engagement. Clarke apparently knew from the beginning that Turing was gay, but didn’t mind. In fact, some accounts say that it was common knowledge at Bletchley Park that Turing was gay. That, in fact, there was a relatively open gay subculture there, and there were men who Turing could have been involved with.³⁷ He ended up breaking off the engagement, but he and Joan Clarke remained friends for the rest of his life. 

Around the same time of his engagement, Turing became nervous that he was going to lose his savings due to wartime uncertainty. He invested his cash into two bars of silver, 3,200 ounces each.³⁸ At the time, they were worth about £250–today that’s about £9,500 adjusted for inflation, but that same amount of silver would fetch about £150,000 at the spot price. Which is wild. He buried the silver bars on the grounds of Bletchley Park and left himself a code to find them again after the war was over. However, when he returned to Bletchley to dig them back up, the constant renovations had rendered the area unrecognizable from what it had looked like in the early 1940s. Turing wasn’t able to break his own code, and so the silver was never found. Some people think it’s still out there, and it’s referred to as Turing’s Treasure. 

Now, I want to emphasize how important the work at Bletchley Park was to the British war effort. Churchill called them his “secret weapon”, even going so far as to joke that he was reading Hitler’s mail before Hitler was.³⁹ When Turing wrote to Churchill in 1941 complaining about shortages and bottlenecks at Bletchley Park, Churchill memo’d his chief of staff the same day saying, quote, “ACTION THIS DAY: Make sure they have all they want on extreme priority.”⁴⁰ Churchill seemed to realize that the war might not be won without the efforts of the Bletchley Park codebreakers. Later, the D-Day invasion of France in June 1944 was only possible because British codebreakers had already broken German codes.⁴¹ Not only would the necessary massing of troops in southern England not have been possible if the U-boats had still been sinking ships in the Atlantic, but Turing and his colleagues were able to track German counter-preparations and pass that information on to the RAF and British navy. 

In 1942, the tide began to turn against the German military. The U-boats were neutralized, which freed up focus and supplies for the fight in the Middle East and North Africa. Now, Turing's bombes were focused on helping defeat Field Marshal Erwin Rommel in North Africa. They were able to read his messages alerting military officials in Germany that fuel shortages were rendering his tanks ineffective. The fuel shortages themselves were actually a result of the codebreakers–they had been unmasking the German and Italian ships that were carrying supplies to Rommel, enabling Royal Air Force pilots to target and sink ships carrying supplies while minimizing civilian deaths.⁴²

The Second Battle of El Alamein began on October 23rd, 1942. Ten days later, on November 2nd, Rommel send a, quote, “broken message” confessing that, quote, “the gradual annihilation fo the army must be faced.”⁴³ Hitler responded that Rommel must not yield; Hitler ordered that he must follow, quote, “the road leading to death or victory.”⁴⁴ This was a huge moral boost for British forces; they ended up winning the battle on November 11. This ended the German threat to the Suez Canal and Persian oil fields, which were key strategic holdings. It was also the first major Allied victory in almost a year, and after the year they’d been having with the sinkings in the Atlantic, the Allies needed good news.

Later that year, the Germans introduced their new cipher, codenamed Tunny. The messages sent through Tunny often contained high-level German strategy memos, some of which were signed by Hitler directly. I wonder how much this development was inspired by suspicions that their code had been cracked and how much was the usual technological development. For a while, Tunny was defeating the British. But Turing pretty quickly invented a method called “Turingery” for breaking the high level Tunny messages. 

One of Turing’s colleagues at Bletchley, Tommy Flowers, was a pioneer of digital electronics, so he pretty immediately recognized that breaking the German ‘Tunny’ cipher would need the might of digital electronics. He created the machine called Colossus, which we recognize today was the world’s first large-scale electronic digital computer.⁴⁵ Flowers was aware of Turing’s 1936 theory of the universal Turing machine, but he didn’t have the luxury of time to create stored-programming or an ultra flexible machine. He needed Colossus to do one thing: Break Tunny. However, Flowers used Turing’s Turingery method as the seed for the Tunny-cracking algorithms that Colossus ran. When Turing saw Colossus in action, he in turn recognized that technology was finally starting to catch up to his pre-war ideas. He kept this in the back of his mind while he continued to work on the war effort.

Probably as a result of his Turingery work, Turing crossed the Pacific–a dangerous proposition with the U-boats out there, though he had done the important work of cracking the U-boat code, so maybe he felt more comfortable doing this than most. He was bound for the US to help US Navy codebreakers in Washington, D.C. He helped them design their own bombes for cracking codes. 

When he returned to the UK, he was promoted to become a high-level advisor at Bletchley. He also moved to nearby Hanslope Park, where he started working on a portable speech-encryption system. There were many soldiers stationed at Hanslope, and Turing ate in the mess hall with them; it seems that whatever shy tendencies he’d had earlier in his life had faded by this point. In fact, around this time he was described as, quote, “a warm, friendly human being. He was obviously a genius, but he was an approachable and friendly genius. He was always willing to take time and trouble to explain his ideas… He had a very lively imagination and a strong sense of humour–he was a fundamentally serious person, but never unduly austere.”⁴⁶ It makes sense to me that he would be tapped to lead and teach, given this description. While at Hanslope, Turing met his lifelong friends Robin Gandy and Don Bayley. When the war ended in 1945, the three celebrated together with a peaceful country walk. 

After the war ended, a lot of the machines at Bletchley Park were destroyed. In fact, everything that had happened at Bletchley was deemed whatever the British version of Top Secret is; it would be decades before people knew what had really happened at Bletchley. 

Turing was recruited to work at the National Physical Laboratory, NPL, to design an electronic universal Turing machine. Since his work at Bletchley was mostly secret–though there were whispers–Turing was hired for  this role largely on the strength of his pre-war work.  After the war, there was this race to see who would build the first electronic computer, though it was exactly called that yet. The main competitors were the NPL and Manchester University. 

In 1945, he completed the design of his Automatic Computing Engine, called ACE, which had a processor speed of 1 MHz. To be clear, this would have been more powerful than the computers Apple started with a few decades later. However, NPL really dragged their feet when it came to Turing actually building the machine. The director of the NPL, Charles Darwin, the grandson of the Charles Darwin, considered Turing’s work theoretical, in large part because he didn’t know about what Turing had done at Bletchley in terms of actually building machines. A paper he wrote proposing various uses a computer could have was deemed, quote, “a schoolboy’s essay not suitable for publication” by the famous grandson.⁴⁷ Instead they wanted to outsource a lot of the actual building of the machines, but that wasn’t going well, and they made very little progress. In general, there was a lot of red tape at NPL that Turing was frustrated by. 

When he was in his early thirties, Turing began channeling that frustration into running. He was already pretty athletic–I mentioned his running chase game earlier–and had come in first in a one-mile race while at Hanslope, but this was when he began running long-distance. He joined the nearby Walton Athletic Club and won many long-distance races there. He eventually came in fifth in a qualifying race for the 1948 Olympics! He was really good! Which feels a little unfair for us mere mortals, but here we are. He decided to enter the Olympic trials but ended up dropping out due to hip pain. Nevertheless, he would regularly run 15 miles from the NPL to Tommy Flowers’ lab in North London. The two had worked together at Bletchley, and Flowers was continuing his own work on computing machines. Turing helped him out by consulting on hardware. 

While at NPL, Turing developed the concept of self-modifying programs, and of programs that can modify other programs. Today we have these, it’s called compiling. In 1946, he presented a report titled “Proposed electronic calculator” to the NPL’s Executive Committee.⁴⁸ It contained the first ever detailed design of a stored-program computer. He was envisioning a machine that could do multiple tasks, like calculate equations and do word processing. Today, when we have that machine on every desk and really, in our pockets, it doesn’t seem that revolutionary. But up until this point, inventors really designed one machine per task. Things had dedicated uses. The idea that the computer could have multiple uses and perform multiple, even unrelated tasks, was truly revolutionary. Today, every smartphone and laptop in the world does this, and we thank Turing for proposing the concept first. 

Sometime after this, Turing was awarded the OBE, the Officer of the Order of the British Empire, which was given to him by King George VI in acknowledgment his wartime service. It arrived in the post and he lost it, apparently. I think the accolades didn’t matter that much to him. 

I also want to note that it’s unclear to me whether or not we’re technically supposed to address him as Sir Alan Turing. As an OBE recipient, we should, but I’m not sure what happens to someone’s OBE if they’re later convicted of a crime, which Turing was. We’ll get more into it in a moment, but if there are any British listeners out there who know the answer, I’d love to hear it. 

Manchester ended up beating NPL to the punch and building an electronic universal computing machine first, which they nicknamed–cutely, I think–Baby. A little baby computer! On Monday June 21st, 1948, Baby ran the first stored program, ushering us into the modern computer age.⁴⁹ Baby was almost big enough to fill an entire room, but future editions would get smaller and smaller. 

Turing must have been both elated and frustrated to hear about the success of Baby. One of the engineers who built Baby, Tom Kilburn, had actually learned the fundamentals of computer science from Alan Turing’s lectures in London in 1946 and 1947. Turing’s mentor and colleague Newman was at Manchester University too, so both ends of Turing’s academic inspirations and successors had built this machine kind of without him. I believe he consulted, and it’s clearly based on his ideas, but he isn’t credited as the creator of it. I think that’s kind of sad.

Frustrated with the NPL, Turing left and planned to take a 12-month sabbatical at Cambridge. His initial plans were to, quote, “play lots of tennis” but he ended up doing “pioneering work” on machine intelligence and invented the lower-upper decomposition method, which I believe is still used to solve matrix equations.⁵⁰

I just want to take a moment to emphasize the timing of this–1936, Turing is proposing the concept of computing. By 1948, he was writing programs for an actual electronic computer. The leaps and bounds that science was making at this time are pretty incredible. 

In 1948, we see Turing come back to some of the ideas that had initially inspired him after his friend Christopher Morcom’s death. He wrote what today is seen as AI’s first “manifesto.”⁵¹ In it, he invented the concepts of a genetic algorithm, neuron-like computing, and a field of study called connectionist AI. He was basically hypothesizing that human “intellectual activity consists mainly of various kinds of search” functions.⁵² He proposed that machines could imitate this and proposed that camera, microphones, loudspeakers, and wheels could easily be used to build a robot. He also developed an early version of the experiment that we now call the Turing test. A year later he’d be quoted telling a reporter that “there’s no reason why computers will not eventually compete on equal terms with human intellect.”⁵³

Around this time, there was a lot of public interest in the idea of a, quote, “artificial brain.”⁵⁴ In 1949, The Times ran an article titled “The Mechanical Brain: Answer found to 300-year-old sum.” It focused on how Turing and Professor Newman had solved a problem that had been posed in the seventeenth century but had needed a computer to solve. In the article, Turing was quoted saying, “This is only a foretaste of what is to come, and only the shadow of what is going to be…It may take years before we settle down to the new possibilities, but I do not see why it should not enter any one of the fields normally covered by the human intellect, and eventually compete on equal terms. I do not think you can even draw the line about sonnets, though perhaps the comparison is perhaps a little bit unfair because a sonnet written by a machine will be better appreciated by another machine.”⁵⁵

Turing brought up sonnets because of something Sir Geoffrey Jefferson, professor of Neurosurgery at the University of Manchester had said–quote, “not until a machine can write a sonnet or compose a concerto because of thoughts and emotions felt, and not by the chance fall of symbols, could we agree that machine equals brain.”⁵⁶

This is really interesting to me because it seems to do two things: The first is to connect art-making intrinsically to humanity, therefore implying that humanity is defined by our ability to create. The second is that this seems to be the inspiration for the proliferation of AI art we’re seeing today. Very early in the nascent stages of artificial intelligence, we see people like Professor Jefferson saying that only the creation of art will mark true artificial intelligence, setting the expectation that the test any AI has to pass is the ability to create art. Whether the people who are making AI capable of creating art today are consciously trying to meet that expectation, or whether that’s just been so built into the field is unclear to me, because I’m not in the field, but this seems to me to be why we’re seeing AI being used to create art instead of other tasks that might make life easier for everyone. No one seems to have foreseen that making this the standard for AI would have other ethical issues, like putting human artists out of business. What is it Jeff Goldblum’s character says in Jurassic Park? You were so busy wondering if you could, you didn’t stop to think whether you should? 

All that said, the ability to create art was not what Turing thought should be the standard for artificial intelligence. Instead, he proposed that the measure of intelligence of a computer should be whether or not the machine could fool a human tester into believing that they were talking to a person. Today we call this the Turing Test, though he called it the Imitation Game. 

The test works like this: a human interviewer asks questions to a computer and a person who are in different rooms that the interviewer can’t see. The interviewer can ask anything, but responses all have to come through text.⁵⁷ The interviewer has five minutes of interaction to ask as many questions as possible and decide which responses are the human’s and which are the computer’s.⁵⁸ The computer passes and is deemed truly intelligent, quote, “If the interrogator cannot distinguish computer from human with better than 70% accuracy.”⁵⁹

This test has flaws, which have been pointed out over time. The biggest is that it is a test of a computer’s ability to mimic human behavior, which is not the same as being intelligent.⁶⁰ Humans, after all, do plenty of stuff that is downright dumb. It also doesn’t account for things like typos or spelling errors that a human might make that a computer wouldn’t. The interviewer might be able to identify which is the computer because the human makes little mistakes, biasing the test against the computer.

The test also presumes that human intelligence is the only form of intelligence.⁶¹ If computers do learn to think for themselves, who's to say that it would manifest the same way human original thought does? Turing kind of knew this–he did say that a sonnet written by a machine might only be appreciated by other machines, but the test he proposes doesn’t totally account for this.

But what is really fascinating about the Turing test, and what makes it endure today, is that it’s “non-essentialist;” that is, in this framing, quote, “intelligence becomes a characteristic of performance rather than something that is innately within us.”⁶² It suggests basically that intelligence is primarily linguistic and, quote, “expressed in the form of social cues through language.”⁶³ Passing the test for the computer then becomes less about getting the quote-unquote “right answer” and more about communicating appropriately with the interviewer. The test is still used today because of how far-reaching this structure Turing set up is. 

Soon after this, Turing’s old mentor, Max Newman, came more clearly back into the picture. Tired of the NPL, Turing accepted Newman’s job offer at the Computing Machine Laboratory at Manchester University, where Baby was. He started work on software for Baby immediately. While there, he designs a chess program called Turochamp with his friend David Chamernowne. Some people call this the first ever AI program.⁶⁴

In 1949, Turing pioneered various debugging techniques. He also gave a lecture titled “Checking a large routine” at a computer conference in Cambridge; today we call this practice “software verification.”⁶⁵ He began writing the world’s first programming manual, which was finished in 1950. That year he also published a paper titled “Computing machinery and intelligence” in the journal Mind, which was incredibly dense but also really insightful. This more than anything else really secured his modern reputation as the father of AI. He was proposing ideas that we are only just now starting to see come to fruition. 

The public became very interested in Turing’s thinking machines and he was invited to give several public talks about this. In a lecture in 1951, he predicted that true AI, quote, “would not take long to outstrip our feeble powers.”⁶⁶ He continued to say that humanity should, quote, “expect the machines to take control.”⁶⁷ Today we call this idea, I, Robot! Okay, I kid–mostly. In fact, Turing had opinions about people being afraid of this exact phenomenon. In that same article in Mind, Turing anticipated and refuted nine arguments against AI. He quickly dismissed people who were against AI just because it was new and different and took on actual substantial arguments. 

One of those arguments, the ninth one to be precise, has long been ignored and glossed over by scientists and writers, but I think it’s worth looking at. It begins, quote, 

I assume that the reader is familiar with the idea of extra-sensory perception and the meaning of the four items of it, viz. Telepathy, clairvoyance, precognition, and psycho-kinesis. These disturbing phenomena seem to deny all our usual scientific ideas. How we should like to discredit them! Unfortunately the statistical evidence, at least for telepathy, is overwhelming.⁶⁸

This is remarkable. Turing is talking about the paranormal and parapsychology as if they were foregone conclusions. Even in Turing’s time these fields of study were hardly “foregone conclusions” however, they were being widely studied in academic circles. The London-based Society for Psychical Research, the SPR, was founded by graduates of Cambridge University for the investigation of, quote, “that large body of debatable phenomena designated b such terms as mesmeric, psychical, and spiritualistic…in the exact same spirit of exact and unimpassioned enquiry which has enabled science to solve so many problems, once no less obscure not less hotly debated.”⁶⁹

The field of parapsychology came into its own in 1930 with the establishment of a department dedicated to it at Duke University. Research into parapsychology was ongoing in the UK in the 1930s and ‘40s, and Turing was probably introduced to it through his friend C.D. Broad, who was a fellow at Trinity College and a member of the SPR. Broad was not alone–after the war, ESP especially was all over the news, but really all of Spiritualism was, probably because folks were trying to emotionally deal with the destruction of WWII. 

All in all, very reputable scientists were insisting that it was just a matter of time until ESP was proven to be a fact of nature; these scientists adopted a position that was, quote, “not dissimilar to Turing’s own in regard to machine intelligence. Like him, they saw themselves as benign on the vanguard, like him they understood that their arguments would meet with considerable resistance.”⁷⁰

Turing was introducing this conversation into his paper about AI to account for how ESP might impact the results of his turing test. “Let us play the imitation game,” he wrote, “using as witnesses a man who is good as a telepathic receiver and a digital computer.”⁷¹ He then described a situation where the interrogator might rig the game either by de-randomize the game using telekinesis or by determining which of the players was the human through clairvoyance or telepathy.⁷²

One of the interesting insights from this argument is how Turing recognized the potential for cheating in the Turing test. He thought that a machine with true intelligence might cheat strategically, deliberately introducing mistakes that would confuse the interrogator. Turing also suggested that telepathic people not be allowed to be interrogators, since their powers would make it too easy for them to tell which was the human, biasing the test. 

The other important insight we can gain from argument nine is Turing’s anxiety about artificial intelligence being subject to bigotry and persecution.⁷³ He predicted that intellectuals in particular would be opposed to AI because they would be afraid of being put out of a job. “Many people are extremely opposed to the idea of [a] machine that thinks,” he wrote, 

simply because they do not like the idea. One can see many features which make it unpleasant. If a machine can think, it might think more intelligently than we do, and then where should we be? Even if we could keep the machine in a subservient position, for instance by turning off the power at strategic moments, we should, as a species, feel greatly humbled.⁷⁴

To be clear, he’s worried about the machines, that they would suffer from the reduction of their freedom. It’s interesting to compare Turing’s worry here with where we are in 2023 with companies trying to use AI to replace artists. 

In 1950, Turing had finally bought a Victorian red-brick home called Hollymeade. It was in Wilmslow, an affluent suburb of Manchester. He wrote to his mother, quote, “I think I shall be very happy here.”⁷⁵ Which if you know what comes next, this line just really stings. 

In 1951, Turing met and picked up a young man named Arnold Murray on Oxford Street in Manchester. They began sleeping together, and around Christmas Turing gave Arnold a penknife as a gift. A few weeks later, in early 1952, Turing’s home was robbed. Among the items stolen was his grandfather’s gold watch, which he was very attached to. Turing immediately suspected Arnold and a friend had robbed him together, so he went to the police to report the theft. 

Remember how I said Turing never bothered to hide his sexuality? Well, he didn’t with the police either. He openly told them how he knew Arnold, as well as the nature of their relationship, and suddenly the police were focusing more on Turing than on the theft he’d experienced. Both he and Arnold were taken into custody. 

Turing’s brother John had grown up to be a solicitor, or a lawyer, so he was consulted when Turing was arrested. John believed the best course of action was to try to minimize publicity to preserve Turing’s reputation, as well as protect their mother from the scandal, so he encouraged Turing to plead guilty during the trial.⁷⁶ Turing did as he was advised, but with a large measure of defiance–he knew that he was the one who had been morally wronged! The items stolen from him were never returned because the police were too busy with the sex scandal. 

Turing was convicted of “gross indecency” under the Criminal Justice Art of 1948. Compared to previous legislation, this law was considered an improvement–remember, fifty or so years before, Oscar Wilde was convicted of the same crime and sentenced to hard labor. Turing was spared that and was able to keep his job because under section 3 of the new law, the court was allowed to award probation as an alternative to prison time. 

However, the act also allowed the court to enforce conditions to probation for the first time; under section, the court was given power to, quote, “include therein a requirement that the offender shall submit, for such period not extending beyond twelve months…to treatment by or under the direction of a duly qualified medical practitioner.”⁷⁷ The power was only supposed to apply if the court believed that, quote, “the mental condition of an offender is such as requires and as may be susceptible to treatment.”⁷⁸ It was under this clause that the court was allowed to force Turing to undergo quote “organo-therapy,” that is, injections of estrogen designed to diminish his sex drive. 

Basically, the court found that Turing was mentally incompetent; that engaging in a homosexual relationship at all meant he was sick, and also that he could be cured with medicine. It’s really vile and upsetting. 

Now this is a controversial point in Turing’s life. If you’ve seen the movie The Imitation Game, Benedict Cumberbatch portrays Turing as really suffering during this chemical castration. He’s stumbling around and can barely think, but that’s very far from the reality of what Turing went through. His body did change as a result of the quote-unquote “treatment”--specifically he developed breasts and gained a lot of weight, but his mind was fine. Turing kept working as before, the only change was that he lost his security clearance as a convicted criminal. He was no longer allowed to consult on codebreaking or government security projects, but he wasn’t mentally compromised by this “organo-therapy.” In fact, one of his friends remembered during this time, Turing, quote, “retained his enormous zest for life.”⁷⁹ He apparently endured the whole ordeal with, quote, “amused fortitude.”⁸⁰ Nevertheless, Turing was disappointed he wouldn’t be able to keep working at GCHQ, the peacetime successor of GC&CS. 

In fact, the same year he started the injections, he published a paper titled “The chemical basis of morphogenesis,” which pioneered a whole new field at the intersection of mathematical biology and artificial life. While still going through this “therapy,” he used an early computer, called a Ferranti Mark I to model biological growth, which was work that wasn’t possible before the invention of computers because it required too many algorithms running for too long. This theory basically explored how things grow, why undifferentiated atoms would begin to differentiate into human limbs or flower petals or bugs, and why those might then arrange themselves into patterns like stripes or freckles. Basically, he was proposing ways that order spontaneously arises from chaos. He called these unknown mechanisms ‘morphogens,’ which comes from Greek for ‘form-originators.’⁸¹

His theories were once again based in math with a dash of physics and chemistry. He used the research to start answering more of the questions he had been interested in after Christopher Morcom’s death. This ordering is a scientific look at the ‘spirit’ organizing principle that he had written an essay about back in 1932. 

Unfortunately, a lot of this work was overshadowed by Cambridge researchers Francis Crick and James Watson, who in March of 1953 cracked the structure of DNA. This discovery of the double helix really pushed biology to focus on molecular biology for generations; Turing’s ideas were very out of fashion and so kind of ignored. It’s only been recently that it’s become trendy for biologists to look beyond DNA to how millions of cells containing the same strands of DNA end up becoming different things, what we call structural biology today. I’m really generalizing, by the way, because I find this all really complicated, so if you are a biologist shouting at the podcast that I’m not explaining this right, I apologize!

In the midst of all this work, the court-mandated hormone injections ended after 12 months, and his life continued on largely the same path it had been before. Though his security clearance was still revoked. 

It is worth noting that this whole court case really soured Turing’s relationship with his family. His nephew, Dermot Turing, wrote that, quote, “there was no way social convention would allow for a discussion about Alan’s sexuality at home–to use an anachronism, it was something that his mother would not be able to compute. Alan had found his brother’s exasperated handling of the case insensitive, with unworthy words exchanged, which both of them regretted. These wounds needed time to heal, but time was running out.”⁸²

It’s also worth noting that this quote-unquote “treatment” did not change Turing. The idea was that somehow the injection of estrogen would make him less attracted to men, and quote-unquote “heal” whatever made him gay–again, gross–but it didn’t because that’s not how attraction works. Toward the end of the treatment, when the hormones theoretically would have been having the most impact, he still found men that he met, quote, “luscious,” as he wrote in a letter to his friend Robin Gandy.⁸³

Sometime during or after all this, Turing wrote a short story. The protagonist is a scientist named Alex Pryce, who works at Manchester University–a hardly disguised Alan Turing. Turing wrote that Pryce had made an important discovery in his twenties, which came to be called “Pryce’s buoy,” which is clearly a proxy for the universal Turing machine.⁸⁴ “The rather obvious double-entendre rather pleased him too,” Turing wrote, “[Pryce] always liked to parade his homosexuality and in suitable company Alec would pretend that the word was spelt without the ‘u.’”⁸⁵ While out and about in Manchester, Pryce meets a handsome youth lounging on a bench, Ronald, who keeps company with petty criminals and makes a small income from male prostitution. Alec glances at him, so Ronald calls out to him, and the two go have lunch at a restaurant. Ronald meanly thinks that beggars can’t be choosers, so he sleeps with Alec. 

The story was never finished, but it clearly parallelled what really happened between Turing and Arnold; the character name Ronald is even an anagram of Arnold. It shows us how Turing saw himself–a little prideful and not able to identify when someone is going to take advantage of him. I wonder how he would have ended it, if he’d been able to. 

In 1953, Turing was appointed to Readership in the Theory of Computing at Manchester, which sounds like a new class today, honestly. I think this shows clearly that his colleagues didn’t care about this gross indecency conviction and it didn’t change his standing in his world, though it impacted his public reputation for decades. 

In early 1954, Turing published his final paper, “Solvable and unsolvable problems.” The title of which sounds a bit menacing considering that he was found dead a couple months later. Turing died sometime on the night of Monday June 7th, 1954 at his home in Wilmslow. His body was found by his housekeeper, Eliza Clayton. 

For many years, the consensus was the Turing died by suicide. A half-eaten apple was found on his bedside table, and it features heavily in this tragic story that Turing dosed the apple with cyanide and ate it so he’d die in his sleep. This was the theory the police put forward and it was accepted unquestioningly by a lot of people, but not by people who knew Turing. 

This theory has come under fire for many reasons, including the fact that this poisoned apple theory was never tested. The apple found at Turing’s bedside was never tested for traces of cyanide. Turing also was well-known to eat an apple every night before bed, so there’s nothing special about the apple being at his bedside. Turing also didn’t leave a note which seems unlike him, who documented everything. Surely if he’d decided to take his own life, he would have documented that decision somehow. 

Many of Turing’s friends would later point out that the police never questioned anybody about Turing’s death. They just assumed suicide based on the 1952 conviction and the fact that he was gay, which in the 1950s was synonymous with being mentally ill. In fact, the coroner at the inquest said, quote, “In a man of his type, one never knows what his mental processes are going to do next.”⁸⁶ Nice homophobia, buddy. Today, this scant evidence would never return a verdict of suicide. It’s just not enough.  

In their own recollections of Turing, many of his friends deny that Turing could have or would have died of suicide. And they have a lot of evidence to support this. Turing was doing well in his career and really excited about the future of his work in morphogenesis. The day that Turing was found dead, he actually had plans with Bernard Richards, a friend and colleague, to discuss experiments that had yielded some significant results confirming his Turing’s theories about biological growth.⁸⁷ He had just gone on a lovely vacation on the Greek island of Corfu and was planning another. He had started experimenting with fiction writing, and he had more math experiments that he had started taking notes on but hadn’t shared with anyone. 

When we talk about external signs that someone was thinking about suicide, we talk about giving away possessions, letting go of their appearance, and no longer making plans for the future. Turing was not doing any of those things. For example, the Friday before his death, he had left himself a list of things he needed to accomplish at work the following week.⁸⁸ In fact, just a couple weeks before his death, he had rewritten his will with the curious clause to give his housekeeper, Eliza Clayton, an extra financial bonus for every year she had served him, starting that year. If he was planning his suicide, why plan for an interest-based bequest for his housekeeper? It just doesn’t make any sense. It seems that Turing imagined that this bonus would have accrued with years of working for him. 

I want to underline that there was very little investigation into Turing’s death. A coroner performed an autopsy, which was standard procedure, but even that initial autopsy report discredits the suicide claim. That report notes that his organs smelled like almonds, which is the main indicator for cyanide poisoning, but did not note symptoms we would expect if Turing had ingested the cyanide. If he had eaten it, even disguised in an apple, there would have been burning around his mouth and in his esophagus. There was not. That he died of cyanide poisoning is not really in question; how the cyanide got into his system is. 

There are two prevailing theories: 

The first, and the one that most of Turing’s friends believed, is that he accidentally inhaled cyanide gas. Turing was known to be experimenting with potassium cyanide at the time; he was using it to melt gold as part of an experiment. When he was found dead, an experiment was still going on in his adjoining study, which he called his nightmare room. There was definitely something bubbling in a pan, something which presumably Turing planned to check on again.⁸⁹ Unfortunately it seems like what was being experimented on was not cataloged, so we can’t say for sure. People noted that the nightmare room had a “strong smell of cyanide” when his body was found, and that there was cyanide in a glass jar near the heating element.⁹⁰ So accidental inhalation or accidental ingestion is the more popular theory today. 

There is, however, a theory that Turing was assassinated by his own government. Obviously this sounds like a conspiracy theory, but I will point out that numerous inquests and government committees have said that Martin Luther King, Jr. was probably assassinated by someone in the US government, so this is not an impossible theory. It’s not unheard for governments to assassinate their own citizens when those citizens pose a potential threat. It’s also worth noting that this theory has been around for a while–even before Turing’s work with breaking the Enigma code was declassified, there were rumors that he had been killed by British Intelligence.⁹¹

Did Turing pose a threat? Not from our perspective. But in the 1950s, like I said, being openly gay in the UK was not only illegal but still considered a mental health issue. People who experienced same-sex attraction were considered unstable and untrustworthy. Turing not only knew a lot about the government from his classified work at Bletchley Park, but he was still being consulted on national security projects at the time of his arrest. It’s not outside the realm of possibility that Turing’s conviction, and the circumstances it came out of–namely this illicit relationship with Arnold and the theft at his home–would have made intelligence leaders in the UK nervous. In fact, we know that it did because Turing lost his security clearance due to his conviction. 

We also know that the British authorities were watching Turing really closely after his conviction. They knew that Turing’s quote-unquote “treatment” didn’t work and he was still very attracted to men and was opening his home to other quote-unquote “untrustworthy” and “unstable” men, which I’m sure in their minds translated to a threat that someone might get their hands on classified information that they could then sell to the highest bidder. We know that they knew because a friend of Turing’s, Kjell Carlsen, tried to visit him in 1953; Jack Copeland describest Kjell as a “Norwegian boyfriend” of Turing’s.⁹² Though Turing described his relationship with Kjell as “perfect virtue and chastity,” the two had shared a kiss in the past.⁹³ The police were apparently monitoring Turing’s mail because when they found a postcard from Kjell announcing his visit, “police over the north of England were out searching for him.”⁹⁴

Kjell never made it to Turing’s home and was deported back to Norway. This was the ultimate nightmare right–a foreign national seducing a man who knew government secrets, a man who the authorities now thought was sick and untrustworthy because of his sexuality. 

Turing posing a risk would have seemed especially real in 1953, because just two years before Guy Burgess and Donald Maclean, two gay Cambridge intellectuals, had defected to Moscow. The scandal linked treason, academics, and homosexuality in the minds of the public; when Turing was convicted a year after Burgess and Maclean, the links were drawn. It didn’t help that the Manchester computer was being used for atomic weapons work while Turing was working there, and he had been consulted on that work from the start. At basically the same time the Kjell was trying to visit Turing, Ethel and Julius Rosenberg were executed in the US for passing atomic secrets to the USSR; the former allies were all whipped into a frenzy of security anxiety, and it seemed to center around these intellectuals who they couldn’t understand. 

So, did the British Intelligence assassinate Turing? There’s no actual evidence. Everything I’ve said is circumstantial, though it is an interesting theory. Killing Turing and making it look like a suicide might have seemed like the best way to prevent a security leak. People put forward this theory because suicide and accidental death both seem incredibly unlikely to people who knew Turing. He was happy and doing well, that is not in question. Nor is the fact that Turing knew the dangers of cyanide well; that he would ever accidentally ingest cyanide seemed as far-fetched to some of his friends as the suicide theory. 

Ultimately, we will probably never really know how Alan Turing died. He passed away at just 41 years old, with the whole world ahead of him. 

After his death, hundreds of papers covered with mathematical symbols and theories were found in Turing’s home. Many of them still haven’t been deciphered.⁹⁵ They weren’t encoded, the math is just so theoretical as to be still untestable in many ways even today. Moreover, Turing’s handwriting never improved after he left school, and he continued utilizing mathematical notation that was unique to him and “unintelligible” to other experts in the field.⁹⁶ We have only recently begun to develop the technology we need to test some of Turing’s theories; I expect that in the next fifty years we’ll be hearing a lot about how Turing was right about various ideas that we couldn’t test until now. 

The story of Alan Turing’s intelligence work during World War II was not declassified during his mother’s lifetime, so Sara never knew what a hero her son was. Turing’s reputation was relegated to the shadows until his story was resurrected in 1983 by Andrew Hodges in his biography of Turing, titled Alan Turing: The Enigma. That book serves as the basis for the movie The Imitation Game, though actually a lot of information about Turing has been declassified and released since it was published so the biography is pretty out of date. If you’re interested in reading more about Turing, I recommend the book The Turing Guide, which collected writings by several people who knew Turing during his lifetime. It covers both his life and his work in equal parts, which is surprisingly uncommon. 

In 2009, then-Prime Minister Gordon Brown publicly apologized to Turing for the way he was treated. He said, quote, “While Turing was dealt with under the law of the time, and we can’t put the clock back, his treatment was of course utterly unfair, and I am pleased ot have the chance to say how deeply sorry I and we all are for what happened to him.”⁹⁷

2012 was the centenary of Alan Turing’s birth. It was declared the year of Alan Turing, and hundreds of events, symposiums, lectures, and more celebrated him and his work that year. In 2013, Queen Elizabeth II officially pardoned Turing. I wonder if he would have wanted this–no one else who was convicted under ‘gross indecency’ laws have been pardoned, to my knowledge. While Turing never believed there was anything to be ashamed of regarding his sexuality, I have to wonder if he would have preferred to symbolically stand with the thousands of men who suffered under this unjust law like he had. 

Homosexuality remained completely illegal in the UK until 1967, when it was partially decriminalized. It would be 2013 before homosexual acts were fully decriminalized.⁹⁸ As late as 1998, seven men in Bolton were convicted of having sex with each other.⁹⁹

Clearly, the 1967 law left a lot to be desired in terms of equality.

That is the story of Alan Turing! I hope you enjoyed this episode! If you did, please tell a friend about it. You can also let me know your thoughts by following me on Twitter and Instagram as unrulyfigures, or by joining us over on Substack at unrulyfigures.substack.com. If you have a moment, please give this show a five-star review on Spotify or Apple Podcasts–it really does help other folks find this work. Thanks for listening!

📚 Bibliography

“Alan Turing.” In Wikipedia, June 6, 2023. https://en.wikipedia.org/w/index.php?title=Alan_Turing&oldid=1158840581.

“Alan Turing - a Short Biography.” Accessed June 6, 2023. https://www.turing.org.uk/publications/dnb.html.

Bowen, Jonathan P. “The Impact of Alan Turing: Formal Methods and Beyond.” In Engineering Trustworthy Software Systems, edited by Jonathan P. Bowen, Zhiming Liu, and Zili Zhang, 11430:202–35. Lecture Notes in Computer Science. Cham: Springer International Publishing, 2019. https://doi.org/10.1007/978-3-030-17601-3_5.

Copeland, B.J. “Alan Turing | Biography, Facts, Computer, Machine, Education, & Death.” In Britannica, June 3, 2023. https://www.britannica.com/biography/Alan-Turing.

Copeland, Jack, Jonathan Bowen, Mark Sprevak, and Robin Wilson. The Turing Guide. Kindle; Illustrated edition. OUP Oxford, 2017.

Dowdey, Sarah, and Deblina Chakraborty. “Alan Turing: Codebreaker - Stuff You Missed in History Class.” Stuff You Missed in History Class. Accessed September 10, 2012. https://www.iheart.com/podcast/105-stuff-you-missed-in-histor-21124503/episode/alan-turing-codebreaker-30207926/.

Kelkar, Shreeharsh. “Difficult to Decode: Alan Turing’s Life and Its Implications.” Science in the News (blog), July 3, 2012. https://sitn.hms.harvard.edu/flash/2012/turing-biography/.

King’s College Cambridge. “Glossary.” Accessed June 5, 2023. https://www.kings.cam.ac.uk/archive-centre/introduction-to-archives/glossary.

“Logical Intuition.” In Wikipedia, June 9, 2022. https://en.wikipedia.org/w/index.php?title=Logical_intuition&oldid=1092319212.

Ottaviani, Jim. The Imitation Game: Alan Turing Decoded. Abrams ComicArts, 2019.

Tan, Cheston. “Artificial Intelligence: Will Computers Pass the Turing Test by 2029? Does It Matter?” Science in the News (blog), July 3, 2012. https://sitn.hms.harvard.edu/flash/2012/ai/.

Tatchell, Peter. “Don’t Fall for the Myth That It’s 50 Years since We Decriminalised Homosexuality.” The Guardian, May 23, 2017, sec. Opinion. https://www.theguardian.com/commentisfree/2017/may/23/fifty-years-gay-liberation-uk-barely-four-1967-act.

The New York Times. “Overlooked No More: Alan Turing, Condemned Code Breaker and Computer Visionary.” June 5, 2019, sec. Obituaries. https://www.nytimes.com/2019/06/05/obituaries/alan-turing-overlooked.html.

Wintour, Patrick, and chief political correspondent. “Gay Sex Group Offered £15,000 Compensation.” The Guardian, July 27, 2001, sec. UK news. https://www.theguardian.com/uk/2001/jul/27/patrickwintour.

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FYI: A few of the links in this post are affiliate links. That just means if you click through a buy a book, I’ll get a few cents of profit but it won’t cost any more for you.

1. Jack Copeland et al., The Turing Guide, Kindle; Illustrated edition (OUP Oxford, 2017), 4 

2. Jim Ottaviani, The Imitation Game: Alan Turing Decoded (Abrams ComicArts, 2019), 5

3. Turing Guide, 21

4. Ottaviani, 37

5. Ottaviani, 18

6. Turing Guide, 372

7. Ottaviani, 19

8. Turing Guide, 353

9. Ottaviani, 23

10. Ottaviani, 23

11. Turing Guide, 352

12. Turing Guide, 21

13. B.J. Copeland, “Alan Turing | Biography, Facts, Computer, Machine, Education, & Death,” in Britannica, June 3, 2023, https://www.britannica.com/biography/Alan-Turing.

14. Turing Guide, 44

15. Turing Guide, 58

16. Turing Guide, 60

17. Turing Guide, 54

18. Turing Guide, 49

19. Turing Guide, 61

20. Turing Guide, 63

21. “Logical Intuition,” in Wikipedia, June 9, 2022, https://en.wikipedia.org/w/index.php?title=Logical_intuition&oldid=1092319212.

22. Turing Guide, 7

23. Ottaviani, 62

24. Turing Guide, 21

25. Turing Guide, 90

26. Turing Guide, 33

27. Turing Guide, 34

28. Turing Guide, 34

29. Turing Guide, 34

30. Turing Guide, 80

31. Turing Guide, 80

32. Turing Guide, 104

33. Turing Guide, 104

34. Turing Guide, 99

35. Turing Guide, 79

36. Ottaviani, 89

37. Ottaviani, 77

38. “Alan Turing,” in Wikipedia, June 6, 2023, https://en.wikipedia.org/w/index.php?title=Alan_Turing&oldid=1158840581.

39. Sarah Dowdey and Deblina Chakraborty, “Alan Turing: Codebreaker - Stuff You Missed in History Class,” Stuff You Missed in History Class, accessed September 10, 2012, https://www.iheart.com/podcast/105-stuff-you-missed-in-histor-21124503/episode/alan-turing-codebreaker-30207926/.

40. Turing Guide, 8

41. Turing Guide, 94

42. Turing Guide, 82

43. Turing Guide, 82

44. Turing Guide, 82

45. Turing Guide, 50

46. Turing Guide, 32

47. Turing Guide, 25

48. Turing Guide, 10

49. Turing Guide, 50

50. Turing Guide, 11

51. Turing Guide, 11

52. Turing Guide, 11

53. Turing Guide, 12

54. Turing Guide, 25

55. Turing Guide, 25

56. Turing Guide, 26

57. Cheston Tan, “Artificial Intelligence: Will Computers Pass the Turing Test by 2029? Does It Matter?,” Science in the News (blog), July 3, 2012, https://sitn.hms.harvard.edu/flash/2012/ai/.

58. Tan

59. Tan

60. Tan

61. Tan

62. Shreeharsh Kelkar, “Difficult to Decode: Alan Turing’s Life and Its Implications,” Science in the News (blog), July 3, 2012, https://sitn.hms.harvard.edu/flash/2012/turing-biography/.

63. Kelkar

64. Turing Guide, 12

65. Turing Guide, 12

66. Turing Guide, 12

67. Turing Guide, 13

68. Turing Guide, 347

69. Turing Guide, 347

70. Turing Guide, 351

71. Turing Guide, 353

72. Turing Guide, 354

73. Turing Guide, 355

74. Turing Guide, 355

75. Turing Guide, 12

76. Turing Guide, 26

77. Turing Guide, 27

78. Turing Guide, 27

79. Turing Guide, 32

80. Turing Guide, 37

81. Turing Guide, 360

82. Turing Guide, 27

83. Turing Guide, 37

84. Turing Guide, 35

85. Turing Guide, 35

86. Turing Guide, 14

87. Turing Guide, 40

88. Turing Guide, 40

89. Turing Guide, 15

90. Turing Guide, 15

91. Turing Guide, 43

92. Turing Guide, 38

93. Turing Guide, 38

94. Turing Guide, 38

95. Turing Guide, 372

96. Turing Guide, 370

97. Turing Guide, 16

98. Peter Tatchell, “Don’t Fall for the Myth That It’s 50 Years since We Decriminalised Homosexuality,” The Guardian, May 23, 2017, sec. Opinion, https://www.theguardian.com/commentisfree/2017/may/23/fifty-years-gay-liberation-uk-barely-four-1967-act.

99. Patrick Wintour and chief political correspondent, “Gay Sex Group Offered £15,000 Compensation,” The Guardian, July 27, 2001, sec. UK news, https://www.theguardian.com/uk/2001/jul/27/patrickwintour.