Deciphering Alan Turing, with Andrew Hodges

December 01, 2014

Alan Turing was a true visionary. Founding what we understand today as computer science, he was also a mathematician, a philosopher, and an early trailblazer for gay equality. Without his genius for codebreaking, the Second World War might have gone in a much darker direction. He saved millions of lives and potentially the world as we know it, yet his efforts for humanity were not enough to spare him the inhuman treatment he received for his sexual orientation.

Andrew Hodges was one of the first people to realize the multifaceted brilliance of Alan Turing, which eventually led him to write the renowned biography, Alan Turing: The Enigma, which was recently adapted into the film The Imitation Game starring Benedict Cumberbatch. Like Turing, Hodges is a mathematician and gay rights activist, and understands first hand the impact Turing’s life has had on our world today.

This week on Point of Inquiry, Hodges explains how Turing became so influential in so many different fields, and how his genius was so far ahead of his time.

This is point of inquiry for Monday, December 1st, 2014. 

On Josh Zepps, host of Huff Post Live. And this is the podcast of the Center for Inquiry. This Thanksgiving weekend, Hollywood released The Imitation Game starring Benedict Cumberbatch and Keira Knightley about the life of the British mathematician Alan Turing. It is barely an exaggeration, of course, to say that Turing saved the allies from the Nazis, invented the computer and artificial intelligence, and anticipated gay liberation by decades, all before his suicide at the age of 41. The movie is based on Turing’s definitive biography, The Enigma, which The New Yorker calls one of the finest scientific biographies ever written. Its author is a British mathematician, Andrew Hodges. And he joins me to discuss the life and legacy of Alan Turing. Andrew, thanks for being on point of inquiry. 

It’s great to be on. The first thing I’m interested in is, I guess, you know, Turing’s known for laying the foundations for modern computer science, and you’re a mathematician. When did you become fascinated by him as a human? 

Yeah, no, this is a very long time ago in the well. And I was a student in 1969 or so, which is in the dark ages. But as a human being. Then it leapt out at me when I met friends is through the gay rights movements of the early 1970s who told me this story. They had this terrible case from the nineteen fifties after what had happened to him. And I said, cos I put this together. I mean the fact that I knew his name really meant something that would happen in 71 that didn’t get me onto writing books at that stage. But what happened was that later on in the seventies it came out that he had not only had this strange two different basis to his life and had another one as well, which was that he’d been the most important person in their code breaking effort during the Second World War. So that was the point. I felt there were very few people who knew that all of these things and had a handle on them. It needed something to bring them all together. Yeah. A unified picture. 

Speaking of a unified picture of that, sort of takes us easily into into his great contributions. Right. I think everyone knows the code breaking story broadly. And that’s probably where a lot of people’s minds go when they hear the name. How did he get into that? What was he mucking around with when he was a young man? 

Yes. Well, that’s interesting. You say that that his best, best known. But that now goes because that was all completely secret until the 70s. He was famous in computer science for what he did before the war and the concept of the Turing machine, which is, if I can summarize it, essentially, is he got the idea of a computer program as summarizing everything that you could possibly call a definite method or algorithm for doing something. And he really invented the computer as a way of making that into a real idea. It’s it’s fun. I think he thought of the idea of a program first and then the idea of a computer in which you run the program. 

So break that down for us. I feel like computing is so ubiquitous, especially for people of my generation where we’ve never really known an era without computers that put my mind into the headspace of a world where the concept of a computer is completely unthinkable. What did mathematicians in the 20s before anyone had thought about the idea of a computer? Where were their heads at? 

Well, that’s a very, very good point. It’s almost impossible now to look at your anxieties and not think this is a computer program. This is the idea of a computer. So it’s hard to recall that he really invented these ideas before such things existed in the real world. To look at news where it all came from is something much more abstract than anything you might think or people would normally think. They think that computing came out of doing big calculations, you see, and then you when you did lots of growth and say very fast, then you try and build a better computer and so forth. And I knew it gradually to get the modern idea, but it wasn’t like that at all. His work in the nineteen thirties came out of very abstract philosophical question to do with the foundations of mathematics about what it meant to have a definite method for solving a mathematical problem. Something was very much on the mathematical map after nineteen hundred when the German mathematician David Hilbert put this question among a lot of others as big questions open for the twentieth century. And then then he followed it up and later remarks, which are very influential. And it was something that was transformed by the work of Kurt Girdle in 1931 that made the huge breakthrough a mathematical logic. But this particular question of what is the boundary of what you can call doing something by a method or definite process that still was undefined. 

And that’s partly because it lay outside mathematics. It needs a philosophical discussion of what you mean. What counts as performing a definite method or process. And that’s what Ziering did from a quite abstract point of view. He turns it into something that was very down to earth who recognized it because it’s the idea of a computer program. But again, he wasn’t that he was interested in doing big calculations at that stage. He was thinking about the nature of the mind and what the mind does. And it was by following up that line of thought about what? The most general kind of thing the mine could be doing in carrying out a definite method or process that he came up with the idea of what we now call a computer. 

Are you able to elaborate or expound on for non mathematicians about exactly what he did think? Qualified as a process, as a program? 

Well, it seems in sense now, because it is anything that can be written down as a computer program. But he didn’t have that language. He had a formalism with symbols on paper, but he thought of it as acting like a machine. The machine was very important because people had talked about doing something mechanically. Something without a process means something you set in motion and make it carry on without using any intuition or imagination. So that was the idea. So it’s just like what a computer does. 

How was he received at the time? How was this concept received at the time? Was there pushback from people saying you’re never going to have a machine doing things? 

This was received very well in 1936 as a solution of this general problem, of what you meant in mathematics by a definite method. But it’s only a small corner of mathematics, really, that was concerned with us within that corner. He was very well received and that became very standard idea. But very few people concerned with the world of doing practical computations would have taken any notice of this. Now, Terry was unusual because he did have this interest in doing things in a practical way. And even in 1936, he was thinking about what it would mean to be doing practical stuff. And I think it could well be in his mind, he was already thinking maybe you could build a machine or it would be like a universal machine, which is his idea. You can’t tell. He didn’t write down anything about it, but that was the way his mind went. And at this point, I could come back to an earlier question you asked, which was about how he got into the Codebreaker business. 

And that was going to be my next question. 

All right. Because there is a link here. I mean, there are loads of links here. Actually, there are links all over the place. I mean, there’s a link going back to his earlier life. But why he was thinking so much about what the mind does. And that’s an interesting question again. But let’s go forward a bit from 1936. This is the period of history when everyone who was well-informed knew that the world was heading towards disaster with war with Germany on the horizon. And Alan’s hearing was part of that world. He saw it rather clearly in Cambridge and in Princeton, in the United States, where he was for two years during that period. It must be very obvious. That is all looming up. And he actually develops his ideas from logic in the direction of thinking about codes and ciphers and what it would like to be implementing a cipher scheme on a machine. And some particularly good mechanical methods for doing ciphers. That’s what he thought about. This is a sort of spare time work. It wasn’t what he was officially doing as part of his mathematical career. And he worked on a particular type of machine. We don’t know exactly what it was with a physicist friend of his in the Princeton physics laboratory. So that’s, I think, rather extraordinary connection because that turned out to be exactly the frame of mind that was needed for the British government’s attack on the problem of the German cyclers. I mean, he hit on the very thing they wanted, really, which was someone who could think about problems that a high mathematical level but turn their hand to or something that actually did the job in some way with actual current technology, which he got to know about. 

So that made a really a perfect recruit. And that’s what happened when he came back to England in 1938. He made it known that he was doing this work and it would have been very, very easy for him to make contact with a British government department which did this code breaking work, because there were a number of older fellows in his Cambridge College who had strong connection with that department. One of them being John Maynard Keynes, the economist. And that’s very likely the connection that he made. It would have been is one of these things that works seamlessly in the English system as a last thing. I suppose a good argument came from just the right sort of place and background. Mm hmm. And in the summer of 1938, he became a part time consultant, as we’d say now, or the government code inside the school, which was the government code breaking department. So he he was actually the first mathematical person to come into that. It was rather an old fashioned department. Until then, they’d been working on the way they did in the First World War with Cyprus, which are more language based. And they were stumped really by the machine ciphers that the Germans were using when they needed to jump up a whole different level of attack. And indeed, they advertised during a full time mathematical post very shortly after that. Turing’s entry into it was the beginning of a scientific revolution which very, very rapidly took over and transformed the whole department into something actually was very go ahead and used mathematical and scientific ideas in a big way. 

I just want to stop on the on the mathematics of code breaking for a second, because it can be a bit opaque to people who aren’t mathematicians. How do you this is maybe a silly question. How do you break a code? 

Well, usually you start thinking about this by little tie examples and then work up something like. Complicated. I mean, there’s an old fashioned type of puzzle that you get in newspapers called a cryptogram, where each letter is just encoded into another letter A into a Q and into a P and so forth like that. And then you have a sentence which is all encoded in this way. And then the puzzle is to figure out what’s been coded into what and to recover the original sentence. All right. How do you solve that? I mean, there are an awful lot of possible substitutions. There are in mathematical language, 26 factorial, different ways of doing that, which is some number of million million, million, million type a number. 

But the point is, you don’t look through the more one by one. If you did that, it would take eternity. You can do something much more effective than that, which is the notice that the most common letter is E! So the most common letter, any coded expression is very likely to correspond to a. And then you fill that in and then you use the fact that T is very common to. And then you know, things like, well, you know, in a very rarely followed by any and things like that, you see. So they very quickly break down the number of possibilities into a small number and then finish it off. And that basically is the principle on which most code breaking would work. But the German enigma machine, which was being used for all military communications, was much more complicated. That was it did was to effect that kind of substitution cipher. But a different one for each letter of the message. And that was effected by having a system with roses which moved round and created a difference in substitution of letters. Every time the message stepped on one by one, one letter, they needed a much enhanced version of that idea. And in fact, what Turing’s main principle made, the main method that they used and was Turing’s triumph really was to design a machine which would work and recover the settings of the enigma. Provided you could guess accurately about 25 letters of the message that had been encoded. That was the basic principle that was not at all easy to do that needed extremely clever trick for it to work. And also, you had to have enough familiarity with the messages to guess these 25 letters accurately. 

So that took a lot of preliminary work to buy other slower methods to be able to do that with confidence. But it was actually possible that was done. In fact, it was done very quickly in March, by March of 1940. The machine of this kind had been built and was actually beginning to decipher German Air Force messages. That was only the beginning. I may say. That’s that was a great start and a great triumph, really, for the British establishment to lie because it actually had turned around and adopted a scientific technological thing very quickly and thereafter a triumph for Western civilization and the whole world. Obviously, it’s not that simple because they were. This is not just one enigma system. There will be dozens are over 100 different enigma systems. They all have to be broken as slightly different ways. Are enhancements which came in the naval ciphers, which Turing took on as his particular thing. They were enhanced with an extra sort of password level, which had to be cracked or hacked in modern terms. And he managed to do that. But that took a lot longer and they couldn’t make much headway on that until they’d captured some material on the on the seas. So it needed that coordination with the Navy to do it. They’ve got an exciting story. And then the story got bigger and bigger and actually brought in cooperation with the United States when United States came into the war. And Turing, in fact, was the top level liaison person who set up that whole system with the US Navy people who built Moorcock, 100 other copies of this basic machine. So it turned out a big industrial story, something which started off as a brilliant idea, grew and grew into something that in modern times, you see, it’s like it was like a model of the world, which was the car. It’s a huge data processing system with extremely high level technology and very sophisticated, logical mathematical ideas going into it, involving the work then of thousands of people. But some of them doing many things which nowadays wouldn’t be done by big software system. So it’s like a picture in the 1940s of the kind of world of the computer which came into being in more modern times. 

Yes, I mean, I was referring to the entire program, not just the first machine. And I’m wondering what the impact of the entire program was on computing. I mean, is it conceivable that computing would have evolved as it had were it not for the Second World War and this program? 

All right. 

So now what Turing did with all this was he then put this experience, both of the technology and of the need for algorithmic work of this kind into the plan for a first electronic computer in 1945 and essentially tried to get on with it as quickly as possible. But, of course, other people were approaching the same idea from different perspective. The other great big calculational. Problem is that the atomic bomb program in the United States and that certainly stimulated similar questions about how best to do calculations, which arrived in 1945 at really the same idea of the modern computer in which you have a single machine. But you’d put different programs on it to make you do different things. That was really arrived that at the same time by the mathematician John von Neumann in 1945. A big question we can’t answer is how much advantage Bob Diamond got out of knowing Turing’s ideas and logic from the 1930s. That’s a difficult question. We don’t know a definite answer to that, but it is reasonable to say that probably that idea would have arisen in one form or another fairly soon at that point anyway. 

It didn’t really depend on Turing to do that thing, whereas in contrast, what he did for the naval enigma problem may have been absolutely critical because events move so quickly and you hadn’t gone a long run. You’ve got a very, very short run before events moved on. And there was a real window. And it’s quite arguable that his individual absolutely individual effort in a certain period in 1939, 1940 made all the difference. And that hadn’t been done. The Western allies would have been completely stuck on it. 

When I opened my iPhone, I have a bunch of different apps and I can open an app and be in a completely different experience from the one that I would be having had I chosen to open a different app. When I listen to you talk about the insights of this period, is it fair to say that that is really the singular inside? If you had to put your finger on one that changed from the prettying period to the posturing period, that instead of having a bunch of different machines to all doing different things, you can have one single device. And just depending on how you program it, it could do anything you wanted it to. 

That’s absolutely it. That’s extremely fair. And that’s the example I like to use myself, partially because it’s so visible. Now, you just see the apps on the iPhone, if you like, and you can just get the experience of doing something completely different, just as now I’m using the same machine to do our Skype communication. Then I can do something very different with it. Yeah, but, you know, no application. 

So let’s just talk briefly about his life as a gay man and the persecution that he faced. And also, I suppose the pride is that a fair word to use that with which he regarded his sexuality? He was he was not a shrinking violet about it, was he? 

You’re quite right about of course, you’ve got to see his life as a it wasn’t just one moment and he develops and society develops and changed throughout his whole period. So as a young guy, yes, he was always quite open. 

I mean, he’s emotionally was was quite open and he was protected by being in the Cambridge environment where he was where that particular college situation and where John might may not Kenz and those sort of people was definitely he was very lucky in being there, but it wasn’t terribly confident about his identity at that stage or what to do about it anyway. 

Think think in you very much what it was. But there’s a real problem about how to live in a decent, honest way with it. Not so much happened during the war that really was dominated by work, but afterwards he certainly forms a much clearer impression that he was going to have a life of his own, do his own thing in life, just as he did in science. 

I mean, he very much did his own thing in other ways, and he applied that to sexuality as well. And then, as you say, he wasn’t a shrinking violet and became definitely more exploratory and more clear. It had made relationship was whether it was math, math, mathematics. Students got Neville, who he met in Cambridge in 1948, and that was their best situation. 

He had probably one that was really destroyed by the disastrous thing that happens in Manchester in nineteen fifty one fifty two. And that’s the thing which of course excites so much attention and interest because it got him into such terrible trouble. 

Yes. Tell us about that. 

See, I met this young man in Manchester. It was a very definite meeting spot which was very close to Manchester University. Actually, you can hardly miss it. And he certainly observed this. And then he met a young guy there and it really was not very suitable. Well, it was one of these things. It sir, it wasn’t his very good idea anyway. They met a few times and then it transpired that he had let himself in for petty theft through this relationship. His reaction was entirely to stand up to this because seeing it as a form of blackmail, not to say, oh, well, I can’t do anything about it, because if the police find out about this, his whole attitude was that you already went to the police giving a false story of how he knew what was going on, but that quickly came apart. 

The police were far more interested in discovering that he’d had a sexual relationship with a young man than anything else. And he was arrested under the law, as it was, in which all gay sex was illegal. And it came to trial in early 1952. Now, and the other young man that’s charged in the same way. Both on both on trial. So that was a fair disaster. It was taken very seriously. And as punishment, he had to accept what seems barbaric now, but was seen. Liberal scientific alternative then, which was taking a year’s course of female hormone estrogen and which was meant I mean, the theory was that it would kill his sex or interest altogether. And he accepted that. And the alternative would have been to go to prison and lose everything and work and the computer and everything else that he was working on. And he did that one factor would have been. Well, there are lots of factors. There was a there was a whole increased number of prosecutions at that time under the conservative government of 1951. That’s a big sort of social scare about the danger of vice and gay men. At that time. It was in the news for the first time, really. 

So it was absolutely caught up in this early fifties change that. His reaction was also typical of what happened in the early fifties, that precisely because there was more persecution and publicity. There was a greater consciousness. And that’s when the movements for social change really had their start. It was in reaction to what had happened. The family was all brought out into the open, much more that this war was in its way a positive thing. 

And you’d have the other types of rights and minority movements as well. And he was part of that and had a very definite sense of fighting back. It didn’t just take this and hide away and fade away and disappear. He had a particular way of standing upsurge, which wishes, as he said, well, if I can’t do my thing in this country, I will go abroad. He liked going to Europe very much. He’d been to Europe a number of holidays, and that was his way of asserting his individuality in the two years of 1952 to 1954 when he did die. And that’s a very interesting period. And in a way, that’s period I find most interesting and also most mysterious and the most modern, too, because all the mixture of different features which are coming into his life that had this modern attitude to sexuality and which he was made himself very open and unashamed, even in a quite macho environment like the computer laboratory. He was very up to date work. His mathematical work on mathematical biology actually was something which is only now really being fully appreciated. And he traveled abroad again, more interested in literature, reading. He had a number of different scientific topics going. And he had these these visits abroad where I think they’re very significant. 

I know you haven’t an infinite amount of time with us today. So let’s wind down with a conversation about the Turing test and his ultimate legacy in terms of the way we think about the nature of mind. 

Yes, indeed. Yes. Well, that’s probably what I would have thought you would say was the best known thing that he did. It’s probably right up there is the thing he was most publicly known for because it was well known as a philosophical paper after he published it in 1950. And he went on the radio and talks about it. So it was his foray into science, communication and public science discussion that and if he’d lived it sort of thing, he might have done much more, I would think, on the question of what criteria we would use to determine whether or not a computer was thinking in the way we colloquially use that, the meaning of that word. 

What were his thoughts? 

Well, his thought was that there should be some objective criterion for saying a lot of philosophers would say, oh, no machine can ever be thinking it’s not human. You see it by definition, it’s a machine. So it can’t be thinking. We’re thinking of something only humans do. I think from my perspective, any materialists are sort of scientific perspective. That’s not very satisfactory because it just it’s just so it’s just definition. 

It doesn’t really explain why it is that humans have a physical brain that can do this thing that no other physical object appears to be able to do. So Turing’s idea was to make it a more objective statement and wish you’d actually look at the output from a computer and without knowing who was a computer and compare it with the output of the brain. So we had a game like thing, and it’s a bit of a joke, really. And and a lot of the tests would be establishing that you have a criterion for intelligence, which isn’t just the question of doing big sums or even playing chess, but actually is at a level which includes understanding the joke you see, because that you really wanted to put the bar very high and say, I’m not just thinking about cleverness, I’m thinking about real understanding and participation and what we’d call intelligent communication. So it’s a fun paper and that’s why I think drawing a lot of attention. 

Yeah. And then it’s always fun to to see each year us get closer and closer to the potential to passing the test. The question, though, I think that interests a lot of laypeople and philosophers of mind, I suppose, is whether or not the intelligence of that computer implies any kind of self-awareness. 

He himself dodged that question. He said that’s not what I’m going to consider. And it’s perfectly true that in more recent critiques of that whole situation, a lot of emphasis has been put on that. He wanted his external objective measure of output without asking what the internal. The meaning of consciousness or self awareness is to me, the most trenchant criticism that’s based on this is that a Roger Penrose who I worked with know a lot about. And so he was much more emphasis on this and says that there is a reason why brains are different from computers. 

Brains have actually got something physical about it. We don’t know what it is that actually does correspond to this thing that we call awareness. I think Turing would’ve been very interested in that argument. He had to take that extremely seriously because at root, he was a physical scientist and his earliest interests in the brain and the mind going right back to his boyhood did bring in the nature of quantum mechanics and what people like Edington had said about quantum mechanics back in the 1920s. So he would’ve been very alive affected. There are things that he’s wrote which show in 1951 that he was alive to this question about whether the quantum mechanical nature of matter would make a difference to his arguments about brains and machines and so on. So I think that’s the right line. And you can summarize it rather simply. Actually, in terms of the Turing test, the Turing test purports to put the human and the computer on the same level. They’re competing equally. And then another judge has to decide which is which. But actually, they’re not on equal footing because then the human is telling the truth and the machine is lying because the human is saying I’m human. And their computer saying I’m human. And the computer is lying. So once you bring truth and so it are not just data streams, which is the way Turing was looking at it with messages, you have got a different type of question. 

Isn’t that critics slightly dodging the issue because it’s sort of dealing with the semantics of what it means to be human? If you tweak the claim from I’m human too, I’m self aware, then we wouldn’t know whether the computer is lying or not. 

I see. Well, I’m saying in that answer saying the formalism that the set up of the test. Right. You might think it was symmetrical, but actually it’s not because they actually do. 

I feel like that’s pulling up the computer on a technicality, frankly. 

It is a question of self-awareness. He means whether you really know something and whether you’re just emanating clever remarks about something. And I think that is a entirely legitimate criticism of the Turing test setup. And I would say it’s not fully addressed by Turing documents. And I think that is the line that people have fastened onto, which is a good one. 

Do you personally have a sense of whether or not a computer that was sufficiently advanced could in some sense be aware of its own existence in the same way that we think of ourselves as being conscious? 

Well, I think it’s certainly got a very long way to go. I’m not convinced by things that happen at the moment. 

And there are other questions, too, about the embodiment of the computer, because, in fact, our knowledge of the world through our inputs and outputs is also extremely important. 

And our whole use of language is tied in with our knowledge of the external world in a way that’s different. The computer. So I think there are a whole number of problems. I’d only say that Turing started all these things off, really. I mean, he gave a great big push in this direction and it’s just been extremely stimulating. 

All right, follow up and an extremely stimulating chat and a fascinating guy. 

Thanks so much for being on par growth and jobs. All right. 

Josh Zepps

Josh Zepps

An Australian media personality, political satirist, actor, and TV show host. He lives in Brooklyn, New York. He was a founding host for HuffPost Live.