Alan Turing’s Earthshaking Philosophical Insight

Posted on October 12, 2012 · Posted in Off-topic

Being the curator of the Alan Turing Year exhibition at the Jerusalem Science Museum, I was invited to sit on a panel dedicated to Turing’s legacy at the ICON Science Fiction, Imagination and The Future festival in Tel Aviv. My talk there was well received, and touches on some interesting truths, so I decided to share its content here. I hope you enjoy it as much as I have!

Nathan Zeldes lecture about Alan Turing at ICON TLV 2012

Incidentally, Alan Turing’s life and work will be the basis of a new lecture I will be adding to my public speaking offerings. The subject is a fascinating one on so many levels – from pure technology to historical drama to driving innovation – that it can easily be optimized to benefit both hi-tech and general audiences.

And now, without further ado:

My talk about Alan Turing’s philosophical impact

The mathematician Andrew Hodges, author of the definitive 600-page biography of Alan Turing, also wrote a short book about this British mathematician which was published in the series “The great philosophers”. And I asked myself: what is Alan Turing doing in a series about philosophers, alongside Socrates, Spinoza, and Kant? If you ask anyone what Turing had done, they’ll tell you he cracked the Nazi Enigma cipher using computing machinery. Now, that is the work of a hacker, and indeed Turing was arguably the world’s first hacker; but a hacker is not a philosopher. Or they might tell you he designed the pioneering ACE computer, but that is what Engineers and Computer Scientists do; I’ve been an Intel engineer for many years, and nobody called me a philosopher!

But Turing was definitely a philosopher, and a great one indeed. This first hit me when a colleague who is collaborating with me to create the Turing exhibition in Jerusalem shared this insight with me: “I suddenly get it. This entire exhibition revolves around one concept: We look at the computer and we see ourselves”. So true! I realized that Alan Turing was the first person to attain this insight; he saw it before computers even existed, and continued to develop the idea throughout his tragically short life. The concept reminded me of Charles Darwin’s impact on our self-image: where Darwin put before us the ape and forced us to see a reflection of our physical nature, Turing put before us the computer and forced us to see in it our cognitive nature. The computer and the mind, he realized, are deeply related. This is a huge philosophical breakthrough, with far-reaching implications for Science, Religion, and the Philosophy of Mind. It is also what places Computer Science at the forefront of modern science. Without the relevance to the mind, CS would be out there with Auto-making and Electrical Engineering, useful but intellectually insignificant fields; Turing’s realization put it at the intellectual frontier with Quantum Mechanics and Evolutionary Biology.


Turing’s first approach to this matter comes in 1936, with his first famous paper: “On computable numbers, with an application to the Entscheidungsproblem”. It is a mathematical paper, and titled as one; but it has a surprisingly approachable narrative that begins “We may compare a man in the process of computing a real number to a machine which is only capable of a finite number of conditions…” Later in the paper the man is referred to as a “Computer”, which is what the word meant in those days. Turing is attempting an analysis of how a human computes, in order to capture the essence of this in a formal process that can be implemented in a machine – the so called Turing Machine, which he later proved was equivalent to any computer we will ever build.

The Turing Machine, as you may know, consists of a head scanning and modifying symbols on an infinite tape in accordance with a set of rules. What is less widely realized (until you read the entire article) is that this tape is simply a one-dimensional simplification of the square ruled paper that a human child would use to do sums at school; and the internal states of the machine are analogous to the state of mind of the human. I could hardly believe it: Turing, only 25 years old,  was inventing the computer by deconstructing the mind!

Compare this to Charles Babbage, the inventor of the cogwheel-based Analytical Engine a century earlier. Babbage was attempting to build a far more complex computing engine than Turing’s abstract model, but was doing it by designing explicit mechanisms to carry out each of the required mathematical and logical operations. He did ingenious work, yet his approach had nothing to do with the human brain. Score one for Alan Turing.

Turing’s paper contains the phrase “To each state of mind of the computer corresponds an ‘m-configuration’ of the machine” – where Machine means what we call a computer, and the State of Mind of the Computer means the human’s conscious thought; what, then, of the thoughts of the machine – as embodied in its ‘m-configuration’? I imagine Turing continued to think about all this during his war years at Bletchley Park, but we only see the outcome in 1950, when he publishes his second great paper, “Computing Machinery and Intelligence”. That this appeared in the journal Mind, an unlikely place for a mathematician’s output, is telling in itself.

“Computing Machinery and Intelligence” begins with “I propose to consider the question, ‘Can machines think?’”. This is a true bombshell. The Golem of Prague and similar myths apart, no one has considered it before except the Lady Ada, Countess of Lovelace, who was Babbage’s helper. Ada actually had a fairly deep insight of what the Analytical Engine would do – she foresaw an ability to compose music by computer, for instance – but when it came to thinking, she was firm: “The Analytical Engine has no pretensions to originate anything. It can do whatever we know how to order it to perform”. Another point to Alan Turing, then.

In this paper Turing gives us the Turing Test, which is really the philosophical statement that since I have no idea whether you are conscious, except by observing your conversational behavior, I should extend the same criterion to the machine. This touches the deepest of all philosophical issues, the Mind-Body problem, and clinches Turing’s place as a philosopher. It also opens a major debate, and the paper lists many of the expected objections; Turing’s responses are evidence of his eclectic thinking, covering as they do mathematics, history, biology, theology and more. It’s interesting to consider his response to the Theological objection, i.e. that God has given souls to humans but not to machines; Turing admits his doubts about arguments from religion in general, but nevertheless proceeds to demolish this one by pointing out that God is certainly capable of conferring a soul on a machine if He so chooses, and that once a machine passes the Turing test He would be more likely to find it worthy of a soul. We’re talking here about a man capable of considering the religious essence of electronic computers, in 1950; Can you imagine what he’d be discussing once he saw the Internet?

But he didn’t live to see the Internet. In 1956 the seminal conference at Dartmouth College founded the field of Artificial Intelligence; but Alan Turing was not there. The field he’d birthed was orphaned and relegated to the foster care of capable but lesser minds.

As for ourselves, I said Turing and Darwin put mirrors before us… but Darwin’s chimp stays put, and poses no threat to overtake us; whereas computers evolve at breakneck speed towards the hypothesized technological singularity beyond which they may well leave us behind. This will give growing relevance to provocative questions such as:

  • Will computers ever get smarter than us?
  • Will computers develop self-awareness? If so, will turning one off amount to murder?
  • Will we be able to download our mind to a Disk-on-Key one day?
  • Is our brain just a biochemical computer?
  • Is it possible to simulate the brain on a supercomputer?
  • Are computers that create art really creative?

and lastly,

  • If so – what then?”…

– what about us, of course, not about the computer. Because Turing saw to it that anything that is about the computer is really about us.

Which is why the exhibition I’m helping build in Jerusalem aims to make the visitors look into Turing’s mirror and ask themselves these questions. Our intent is to present Computer Science, as distinct from the Computer itself, and to connect it to Turing’s contribution. This will include exhibits in many areas – algorithms, the limits of computation, artificial intelligence, encryption, the history of computing – and I find that wherever we look at computer science, we see not only ourselves, but Alan Turing, looking right back at us.

What a sad loss.


If you want to order a lecture along the above lines, or a customized one to include more detail about aspects of Turing’s science, cryptography, or life story, drop me a line.


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