Turing, Hofstadter, Bach – with some Cherla thrown in

The imitation game, as described by Alan Turin...
The imitation game, as described by Alan Turing in “Computing Machinery and Intelligence”. Player C, through a series of written questions, attempts to determine which of the two players is a man, and which of the two is the woman. Player A – the man – tires to trick player C into making the wrong decision, while player B tries to help player C. Turing uses this game as the basis for his test for intelligence. (Photo credit: Wikipedia)

A few weeks ago I attended the morning (I had to go back to work in the afternoon) of the BCS doctoral consortium in Covent Garden in London – watching various PhD students present their work to audience of peers.

The presentation which most interested me was that of Srikanth Cherla who is researching connectionist models for music analysis and prediction and to use generative models to produce short passages of music that are in a similar style to the music passages that his systems learn.

It’s not a field that I have any expertise in or indeed much knowledge of, though in essence (I hope I get this right): a specialised form of neural network is used to analyse musical passages (Bach’s chorale works were highlighted) and from there it is possible to get the computer to play some passages it has composed based on the style it has learnt.

Srikanth emphasised that it was not a case of applying a rigid rule that guessed or picked the next note – there is a semi-random/stochastic element that can be attributed to certain musical patterns in the works of the great composers and capturing that is important.

And the music he played at the end – while plainly not matching Bach, did certainly sound like Bach.

As I am (still! It’s a big book) reading Godel, Escher, Bach: An Eternal Golden Braid by Douglas Hofstadter my thoughts were immediately turned to the idea of artificial intelligence and then on to Alan Turing’s idea of the “Imitation Game” and the concept that anything that looks like it is thinking should, in fact, be thought of as thinking.

Today, prior to writing this blog I read through Turing’s October 1950 paper “Computing Machinery and Intelligence“, from which we get the idea of a “Turing Test” (though obviously he doesn’t call it that).

The paper begins:

I propose to consider the question, ‘Can machines think?’

And goes on to discuss ways in which it might be possible “by the end of the century” to have machines which could fool a remote observer, able only to read typed answers to questions, that a digital computer was in fact a person.

The paper is not, for Turing at least, in a completely different field to “On computable numbers”: Turing’s essential point is anything a human computer can do, a digital computer can do, and he goes on to explicitly call humans machines.

The idea that great works of art, such as the “next” set of Bach chorales,  might in the future be composed by computer no doubt horrifies many readers, as it plainly did in Turing’s day too – as he deals specifically with what he calls “the theological objection” – an extreme objection based on the idea that “God gives an immortal soul to every man and woman, but not to any other animal or machine”:

I am unable to accept any part of this… I am not very impressed with theological arguments whatever they may be used to support

But in any case, from within the theological paradigm dismisses it as a human imposition on what is meant to be an unlimited Godly power:

It appears to me the argument quoted above implies a serious restriction on the omnipotence of the Almighty

…before going on to swat aside Biblical literalism as an argument by citing how it was used against Galileo (maybe there are still fundamentalists out there who believe in the literal truth of Psalm 104 and an unmoving Earth but if so they keep quiet about it).

Then he deals with the argument that machines could not appear human because they have no consciousness by essentially asking what is consciousness anyway – and how can we prove others have it and then goes on to deal with “various disabilities” – such as computers being unable to appreciate the taste of strawberries with cream:

The inability to enjoy strawberries and cream may have struck the reader as frivilous. Possibly a machine might be made to enjoy this delicious dish, but any attempt to make one would be idiotic. What is important about this disability is that it contributes to some of the other diabilities e.g. to the difficulty of the same kind of friendliness occurring between man and machine as between white man and white man, or between black man and black man.

This passage is worth quoting as it both suggests that Turing is far from the 100% progressive superhero later admirers are tempted to paint him as – he beat the Nazis and was persecuted as a gay man and therefore can do no wrong: in fact he was a man of his times with all that implies – as well as because I find it less than fully satisfying an answer.

In context I think the point he is seeking to make is that we could make a machine that liked “eating” strawberries and could be friends with its fellows (so long as they had the same skin colour, don’t lets get too radical!) but why would we bother… but it is not totally clear.

Similarly he, like Hofstadter, deals with the so-called Goedalisation argument less than satisfactorily: this states that we, humans, can state true statements about numbers that machines cannot determine (i.e. we know they are true but the machine cannot decide if they are true or false). Hence we could, in the imitation game, pose a Goedel Number type puzzle that the computer could never answer.

Actually, of course, the computer could guess, as humans often do! But the more general point – that humans can do something machines cannot and so we are not truly Turing Machines seems unanswered to me by both Turing and Hofstadter’s argument: that we can also find questions humans cannot determine if we make them complex enough.

Perhaps an expert would care to comment?

Update: Following some feedback from Srikanth I have edited the passages referring to his work slightly – haven’t changed the sense I think but just made it a bit clearer. I also updated the Psalm number – as I had misread Turing’s reference to line 5 of the Psalm for the Psalm itself

6 thoughts on “Turing, Hofstadter, Bach – with some Cherla thrown in

  1. Nice post, I’m actually working on a project involving AI music – it’s just testing out different number systems in genetic algorithm encoding, but the Fibonacci coding led me to music theory and I found a great TEDxTalk with this AI called GenJam. It freestyles off the back of human input, have you heard of it?

    As for the Turing/Hofstadter comments, I re-read an old McCarthy paper recently, “Epistemological problems of artificial intelligence” which I thought was so on point. The jist is big-picture statements can’t be made when the core philosophical structure hasn’t been laid down.

    I’ve just bought a book called “On Intelligence” which is arriving soon, can’t wait to sink my teeth into it!

  2. Although man can do myriad things which machines presently can’t, there’s one thing that a machine could do that man couldn’t, and it would have to be the most important thing ever ideated too, as deemed by both man and machine. Should mankind ever disappear from Earth then the machine could be the only thing left tasked with having to replenish this globe with homosapiens given that the machine could well be — especially so should the occasion arise decidely somewhat later than sooner — sufficiently intelligent to know that it’s still failing miserably, at that time, and likely forever therafter, to even equal or surpass man’s intelligence in its entirety. The machine, then, could only hope that it would succeed in bringing about man’s resurrection — per panspermia or what have you — if only for its needing mankind to then create a more intelligent machine, and so such process would hopefully endure indefinitely, if push came to sh_ove’rt…cete_ris’ing paribUS.

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