Happy Birthday, Mr. Turing


It’s Alan Turing’s birthday!  Google has a nice outline of his life and work for you to check out, and a ribbon-style Turing machine on the Google.com homepage that lets you get an idea for how to do read/write instructions.  (I got sloppy (I’ve only got so much time in theis Starbucks) and accidentally programmed an infinite loop, but luckily Google made sure to include a break).



The definite highlight of my first CS class at college was finding out we would write a ribbon-style Turing machine (just like the one Google did graphically) in Scheme.  Ok, second-best highlight.  The real highlight was when it worked.  (Capering may have been involved, though I managed to restrain myself from calling my parents to boast until the sun had risen).



Of course, you don’t have to build your Turing machines from Lisp dialects (but I prefer to, as a lover of parentheses).  You can build them from Legos.



Though, of course, if you want to see a Turing machine a little closer to hand, you’re already looking at one!  (Assuming you haven’t printed out this blog post).  The reason people get excited about building these in the first place is that a Turing machine is a universal computer.  That means it can simulate any algorithm that can be done on any other kind of computer.  So everything you’re looking at could be computed and summarized by one of the tape machines you saw above using just a few types of commands.



If you’re a regular reader of this blog and not yet in the math-y faction, you may hear about Turing mostly in the context of Turing Tests (ideological or otherwise).  Well, it turns out Bryan Caplan isn’t the only person to come up with the idea of an Ideological Turing Test.  At Cardiff University, they’ve been doing a series of interesting experiments, as detailed by the Atlantic.

In the 2000s, however, Collins, together with colleagues at Cardiff University, tried new Imitation Games to study three things: 1) whether color-blind people could pass an imitation game as color-perceivers, 2) whether those without perfect pitch — the ability to recognise and name a musical note just as most of us can recognise and name a color — could pretend they had perfect pitch, and, 3) whether the blind, proper — at least those who had lost their sight in early childhood — could pretend to be sighted. The new subject matter gave rise to interesting results that followed a particular pattern.

Consider the blind. They spend their whole lives immersed in sight-dominated societies that speak sight-dominated languages. Based on interactional-expertise theory, their exposure to this language should enable them to make the same judgments as sighted people, even where they are discussing things they have never seen, such as the bounce of a tennis ball, its relationship to the line and how hard it is to call it ‘in’ or ‘out’. By contrast, because sighted people lack immersion in blind society, their attempts to pass as blind should come across as more caricatured than authentic. Rather than extrapolating from blind people’s actual discussions of their experiences, sighted people are inclined to imagine by subtraction, guessing, unconvincingly, what it would be like to go through life without seeing.

The other cases yielded similar results: the color-blind were better able to pass as color-perceivers than vice versa, while those with perfect pitch were better able to pass as those without perfect pitch. The reversal of polarity when the color-blind were compared to the pitch-blind was exactly what would be expected. These experiments were a proof of concept, establishing the Imitation Game as a research tool that can reveal interactional expertise in action.

In more recent experiments, it turns out it was a lot easier for students to pass as gay than Christian.



C’mon, you’ve got to be a little tempted to learn computer science by now? You might not be moved by my recent conversion, but perhaps you’re a little moved by my proselytization on this topic?

I’m not asking for a profession of faith, just that you browse the course catalog at Udacity and Coursera, and maybe check out the intro CS class.

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  • Do you always write your 111 Quick Takes in binary and I just now noticed?

    • leahlibresco

      Nope, special occasion!

  • tracer

    oh no .. not lisp … brings back college nightmares … then again, maybe it was the annoying prof. tho it sure does improve your skill in counting/matching parentheses … 1, 2, 3, 4, 3, 4, 5, 6, 5, 4, 3, 2, 3, 4, 5, 6, 7, 8, 7, 8, 7, 6, 5, 6, 5, 4, 5, 4, 3, 2, 3, 2, 1 …

    Lots of Irritating Single Parentheses — oh joy

    • Adrian Ratnapala

      But solving that problem is what indentation is for. But then you could just use Python.
      Leah will never convert me to LISP.

      • leahlibresco

        On this, I am ecumenical.

  • Jon H

    I’m majoring in CS! I’ll be a freshman this fall. I love CS stuff, information theory, logic, math, all that related stuff. Not that I’m very knowledgable in any of it, but it’s all so fascinating. Being introduced to calculus a couple years ago was really cool, and after learning Java this past year, I really wanted to keep pursuing CS.

    • Slan21

      Java is baaaaaaad
      You gotta try projecteuler.net, you may like it (230 solved here 🙂 ).

      I thought you had to do a post about Turing, after your Turing test, for the birthday and because you like computer science (maybe not as much as i do !). Not to mention he was a queer himself, faced a criminal prosecution for that (it was illegal in UK in 1952…), had to undergo chemical castration as an alternative to prison, and (probably) commited suicide two years later.

      And you missed 110 😉

      • R.C.

        Why is Java bad? I love Java.

        Okay, I get that it’s inconvenient because of the delegate thing. I grant that writing a class for event-handling when you wish you could just write a closure a la JavaScript could be annoying from a conceptual standpoint. (But the number of keystrokes isn’t that much more, unless you have the misfortune to be extending a Listener that doesn’t have an implementing Adapter already written.)

        • Slan21

          The Java part was a bit of a free troll, but i really don’t like it.
          It has probably the smallest feature set of any widely used modern language. It’s very boring as far as languages go. There are very few tricks that let you demonstrate to everyone how clever you are. Stylistically and syntactically it’s very plain-Jane, everyone’s code looks like everyone else’s. It’s not “fun” to write and it’s probably the most verbose of any of the major professional development languages. Hardly anyone thinks “Oooh fun I get to write some Java.”

          It’s a successfull language with probably many qualities, but i prefer funnier tools, more elegant, often functionnals ones.

  • The closest I come to CS is running Linux (I’ve used Slack, Mint, and Ubuntu) and having rather an obsession with LaTeX (markup and not a language at all, but still awesome).

    Maybe when I finish my Harvard Open Course on the Hebrew Bible and its interpretation in Judaism and Christianity, I’ll move on to, say, refreshing my Perl skills. But not yet! 😛

    • Fun fact: TeX, and by extension LaTeX, actually is a perfectly cromulent programming language, Turing-complete and all. It’s just that when it’s (ab-)used that way it is not particularly human-readable or efficient.

      • A Philosopher

        Two ways of running Turing machines in LaTeX.

        • That is some of the most AGONIZED LaTeX I have ever looked at. But it was still pretty cool. (I didn’t try it, just looked at the code and gawked.)

          I thought my Master’s Thesis was pretty spiffy, honestly . . . SCHOOLED.

    • R.C.

      Now Perl…that’s an ugly language. Amazing the stuff you can get done, but still: UGLY, you ain’t got no alibi.

  • JohnH

    Technically a computer is not a Turing machine as it has a finite tape.

  • 180_Degrees_From_Sanity

    Yeah, Let me leave this here for you. My favorite tribute to Turing.

  • DrDJ

    What happened to 110?

    • Bill Cook

      Rather Leah missed 111, no?

  • Scheme was my first and only functional programming language…. Never again I say!

    Also, I didn’t realize your level of fluency in CS. You can expect my future comments to take a turn towards algorithmic terminology 🙂

  • charles

    And i am reminded that even if leahs conversion proves uncompelling to me i can rest assured that i will still love this blog. thanks!

    oh and functional programming is mindnumbing, C is where its at.
    and just because we are on the topic of silly religious debates, vim is better than emacs:wq

    update on my fourth grader in the Udacity class: they went a little fast for him, he lost interest in lesson 2. sidetracked by school and minecraft, and RCIA! hell try again over the summer.

    • “and just because we are on the topic of silly religious debates, vim is better than emacs:wq”

      OH NO. This will now surely become a 500-plus comment count monstrosity of a thread! WHAT HAVE YOU DONE? *ducks and hides*

  • Matt

    There’s also http://www.codeacademy.com .

  • Kyle

    One of the best comics from xkcd.

  • Phillip


    Somewhat off topic, but since it’s math related, I was wondering if you could share your thoughts on this article in a future post. Math, God, the Platonism, all the fun stuff.


    “But even greater problems then arise: why should the physical realm emerge from and be rooted in the platonic realm? Why should the mental realm emerge from the physical? Why should the mental realm have any direct connection with the platonic? And in what way do any of these questions differ from those surrounding ancient myths of the emergence of the world from the slain bodies of gods or titans, the Buddha-nature of all natural objects, or the Abrahamic notion that we are “created in the image of God”?

    Indeed, the belief that we live in a divine Universe and partake in a study of the divine mind by studying mathematics and science has arguably been the longest-running motivation for rational thought, from Pythagoras, through Newton, to many scientists today. “God”, in this sense, seems to be neither an object in the space-time world, nor the sum total of objects in that physical world, nor yet an element in the platonic world. Rather, god is something closer to the entirety of the platonic realm. In this way, many of the difficulties outlined above which a platonist faces are identical with those faced by theologians of the Judeo-Christian world — and possibly of other religious or quasi-religious systems.”


  • Paul Precod

    I admit that this is way off-topic, but the other posts’ comment threads are just ridiculously long and deep. Sorry for hijacking.

    I just wanted to check that you will be addressing the question that’s been burning in my mind over the last few days: which is about the factual content of Catholicism.

    Do you believe in a bodily resurrection of Jesus and believers?[1] How about (real, not symbolic) transubstantiation?[2] That the Holy Spirit guides the Church *uniquely*?[3] That it is literally impossible for the Catholic Church to get a question of morality wrong?[4] In the existence of hell?[5]

    [1] Fourth Lateran Council

    [2] Council of Trent

    [3] Pastor aeternus

    [4] First Vatican Council of 1870

    [5] Athanasian Creed

    If you examine these and other factual statements and find that you disagree with them, what will that mean for your Catholicism?

  • CountryMidwife

    I’m quite sure my post won’t move you, Leah. You are beyond smart and thoughtful and and all that left brainedness is surely beyond me. But, if haven’t, could you write a post on this topic? (If you have, point me there, I apologize)…

    Contrary to you, I was raised in a Catholic home but have struggled with faith and belief always. I want in many ways to embrace Christianity because doing so would be a hellavu lot easier in my rural community. And I really do want community. I have a certain, gestalt belief in a higher, loving power, a grand design. I believe said higher power crosses all cultures … “a rose is a rose by any name”… I believe that God reveals to every culture in the way and language said culture understands, and hence I’m a “who do you love? All is One” type believer.

    Ok, my problem with Christianity: to call oneself a Christian you must believe that Jesus Christ was the literally begotten born of a virgin Son of God. If you don’t believe that you cannot call yourself a Christian. I believe that God is neither male nor female, rather a great spirit. I believe that God has sent us many great prophets. I know that Jesus Christ existed historically and was a great human. As I believe was Helen Keller, and Mother Theresa, and Ghandi, and MLK Jr, and hell, Jerry Garcia, and many many other wise souls were as well. Indeed, I believe that we are ALL children of God, products of this Great Design. I cannot believe that one human, who’s words and actions have been subjected to a hundred translations, within who’s book pure cruelty and nonsense exists as well, can be enough to hang my hat on.

    Can you help me with this? Or at least speak to your own wrangling with it? Thank you —

    • John

      Sorry to butt in… “I cannot believe that one human … can be enough to hang my hat on.”
      Neither can I, but I come pretty close to hanging my hat on two: namely my parents.
      They had parents and so on, so it seems reasonable to hang my hat on Adam and Eve, uniquely. After all, she was named “mother of ALL the living.”
      The Christian claim is that there is a new beginning. This is why there is one human… or rather two. Jesus and Mary are the New Adam and the New Eve, defining the new way of being human.
      If we opt for the many, we opt for Adam and Eve, where those many are one. If we opt for a new beginning, there can only be one (two).
      As for cruelty and nonsense, its the bitter pill we’ve been given to swallow. It serves the Doc’s purpose or else it wouldn’t exist. I recommend a reading of Salvifici Doloris on the topic.

  • John

    Do you like your maths discrete or continuous? Elaborate.

  • Michael A Mull

    Pity Turing was a gay atheist and thus denied that grace of God’s love in the afterlife.

  • Casey

    I just saw your piece on CNN, and I think you are an embarrassment to the intellectual community. You sit there and pretend that you are somehow smarter than all other atheists, yet you succumb to the weakest argument of Christianity–that it guides morality. I’m not upset that you “became” a Christian all of a sudden; I’m upset because you did so with little critical thought, and your reasons for doing so are wholly personal and not representative of the atheist community. You are not strong because you changed your mind. You are weak. And you’ve apparently lost the capacity for critical thinking. Shame on you.

    • Tom Leykis

      Casey, she’s just a sexually confused woman who really isn’t truly involved in hard sciences. You’re wasting your time.

      • deiseach

        That’s very bi-phobic of you, Tom. I refer you to the Human Rights Campaign information page for continuing education in modern understanding of the complexities of human sexuality. Attitudes such as yours veer perilously close to hate-speech – and a science-minded, factual, reality-community-based person such as yourself surely wouldn’t want to come off sounding like one of those bigoted fundie religious zealots, now would you?

    • deiseach

      Casey, it was my understanding that there is no such thing as “representative of the atheist community” since atheism is not a belief system, therefore there are no rubrics or dogmas to adhere to, and that many different attitudes and approaches come under the ‘big tent’ of atheism.

      You seem to be expressing a very doctrinaire, ‘one size fits all’ vie of atheism – perhaps Leah did not fit your definition of “what an atheist should be” but there are many variants within atheism, politically, socially and even philosophically.

  • Tom Leykis

    Real scientists and mathematicians don’t convert to the foolishness and ignorance that religion represents. I feel sorry for you and how truly ignorant and delusional you are. You’re just another confused person looking to cling to anything you can to justify your choices. I suggest you read: http://godisimaginary.com/
    and Prof. Richard Dawkins. Perhaps your small mind can grasp the facts.

  • deiseach

    I was going to say this is off-topic to the post, but since Casey and Tom so helpfully introduced the topic, holy cats, girl! You’re famous!

    Just read the Anchoress’ blog and MSNBC covered your story “Libresco did not immediately respond Tuesday to an email from msnbc.com for further comment. ” Yeah, keep ’em waiting – you’re too big for MSNBC! 😉

    Interviewed on CNN? My immediate reaction is one of sympathy 🙂 Well, truly now, we old timers who stasrted following your blog all of months ago can say We Knew You When (back before you were famous and everyone jumped on the bandwagon). Wow – it’s like Six Degrees of Kevin Bacon, round here!

    Now that I’ve stopped laughing, I really must get off my lazy backside and start praying for you. Any specific prayers or devotions or saint you’d like? I generally devote the Angelus by default to these kinds of intentions, since I’m hopeless at praying the Rosary, but if you have a favourite mystery I’ll gladly say a decade of that for you (and you may not have been told this yet, but you do not have to have a devotion to the Rosary to be Catholic. You can go all your life without saying it and still be a good Catholic.)

    And also, if you do go through RCIA and find that there are things you can’t in good conscience accept and so you can’t go for Baptism, that’s fine too. You don’t have to sacrifice reason or conscience and you are not expected to go through with a conversion you don’t fully believe and can’t fully live. I just want to say that because you’re getting a lot of pressure from both sides – maybe the pressure isn’t so overt from the Catholic side, but you are not backed into a corner and don’t have to go through with things because you haven’t burned your bridges. I have enough trust in the Holy Spirit to leave it up to the Third Person of the Trinity, and I have enough trust in your intellectual integrity and strength of character to make your own decisions, but I just thought I’d give you some encouragement (or maybe it’s discouragement, but it’s meant well).

    • leahlibresco

      Much appreciated deiseach. Especially the last paragraph. I only know about so many saints, but I do quite like the argumentative St. Catherine of Alexandria (though maybe I should be looking for someone to balance me out a bit).

      • deiseach

        Catherine of Alexandria is a good saint to pick (if you’re going to go ahead to the Easter Vigil, God willing, you need to think about a saint to take as your patron for your confirmation name and if Catherine appeals to you, that’s perfectly fine).

        She was extremely popular during the Middle Ages, along with Barbara, Lucy and Dorothy (you’ll often see her in paintings as one of the saints sponsoring the donors or in groups with the other virgin martyr saints) and if you pick her, you’ll have your own firework!

      • Ted Seeber

        I find St. Augustine of Hippo to be quite challenging. He’s the one who led me to my private revelation that miracles don’t have to be unexplained.

      • Tom Leykis

        “Saints” are also convenient inventions of man as are the “3 miracles” they never performed that the pope uses to justify beatifying them. Facepalm.

  • Ryan

    “I’m not asking for a profession of faith, just that you browse the course catalog at Udacity and Coursera, and maybe check out the intro CS class.”
    That is a good idea, and I have done just that. Now enrolled in intro to CS at Udacity. Thanks for the suggestion.

    • leahlibresco

      Yay! This made my day.

  • Devin

    The obsession with Turing and his tests makes me think either her conversion is a ploy to test society or she has played us all to begin with. I could care less either way, I am just curious which side wins this time. Just for fun’s sake.