There were some thoughts in this book that didn't appear in my earlier biography Alan Turing: the enigma. The main stimulus was the influence of Roger Penrose's books The emperor's new mind and Shadows of the mind. This passage on the influence of the war, for instance, showed the way my thinking had developed since 1983.
Turing in the Land of NZAlan Turing's life and work touches on many difficult and controversial subjects so I expect criticism. I was rather surprised, however, by the arguments of two philosophers from New Zealand, Copeland and Proudfoot, who reviewed my work in the Times Literary Supplement.
In April 1999 the philosophers published their extraordinary views on Turing's so-called 'Forgotten ideas' in an article in Scientific American.
Comment on Copeland and Proudfoot's OracleAn unexpected result was I found I had more to say about the philosophy of mind and machines than I had realised before.
Here is a lecture, first given at Hamburg in 2000, with the title:Stanford Encyclopedia of Philosophy, to submit an entry on Turing's life and thought.
And in June 2002 I gave a talk which ended the proceedings of the Turing Day at the Federal Institute of Technology, Lausanne, Switzerland.
See my illustrated talk on: What would Alan Turing have done after 1954?
Logical and PhysicalIn Alan Turing: the enigma I had chosen a formal structure of 'logical' and 'physical' life, with a 'bridge passage' set in 1942-43, and I think this was a good point of departure. When Mike Yates edited the last volume of the Turing Collected Works, he asked me to write a piece on The nature of Turing and the physical world which is also on this site, and I now have a number of other publications which reflect on this theme.
Browse my Publications page.The ideas can probably be taken yet further. My own attitude is that there is something to learn from every discussion, and I am used to a culture in mathematical physics where people are always having to reshape and adapt their ideas in the light of new insights. Alan Turing himself was basically an applied mathematician, and that's the spirit in which I approach his ideas. Although I don't agree with Copeland and Proudfoot's conclusions, they have stimulated worthwhile new questions — mainly about how Turing's work relates in fine detail to what is usually called the physical Church-Turing thesis. Also, Copeland noticed one sentence in Turing's 1951 radio talk where he mentioned a problem about quantum mechanics. This is in fact just the objection to Artificial Intelligence theory that Roger Penrose developed into a big new theory in his books. This is all to the good, and I don't mind at all saying that I wish I had noticed this earlier myself!
I am not so keen on philosophers' way of taking up a 'position' and attacking everyone else's, as if it were shameful ever to develop one's views. People argue a great deal about 'Church's thesis' as if it were frozen in time as a dogma. Yes, the historical questions are very interesting, but it might be more interesting to see whether there is a 'Church's synthesis', where logic and physics develop together to give something quite new. This means knowing something about mathematics and physics, not just chopping texts into words.
My detailed review of Copeland's work appears in a special issue of the Notices of the American Mathematical Society. It is available on-line in .pdf form.
Philosophy of Life: Innocence and Experience
In my work I have always wanted to keep in mind Alan Turing as a lively human being, and arid philosophical argument tends to turn him into an textual 'Turing' that I tried to avoid. In addition, his dramatic life and personality continue to raise questions related to moral and political philosophy.
Two publications have more about the moral themes of Alan Turing's extraordinary life as a gay man at the heart of the Anglo-American military machine: Turing — a Cambridge scientific mind and The military use of Alan Turing.
In August 2003 I gave a talk on Alan Turing at Imperial War Museum North. This also formed part of the programme of the lesbian and gay Europride. An article based on my talk, which was designed to link themes of war, sexuality, and science, appears here:
Another Road to Reality: mathematics
Continue to: Turing: a natural philosopher (1997)