Having recently been trying to be less a fossil concerning knowledge of evolution, I’ve watched all sorts of truly excellent documentaries available online. In several of them, it was said that Darwin’s idea of evolution through natural selection is the best idea anyone’s ever had. Because it’s been so powerfully explanatory and has all the marks of great ideas in its simplicity and audacious, unexpected and absolutely revolutionary character.
Uh huh. Ya it’s definitely a good one, that’s for sure. But I’ll tell you an idea that I think is right up there but is nowhere near as widely understood, perhaps permanently so. It’s Turing’s idea of the universal machine. Turing invented the modern computer. This was not at all an engineering feat. It was a mathematical and conceptual feat, because Turing’s machine is abstract, it’s a mathematization of a computer, it’s a theoretical construction.
What puts it in the Darwin range of supreme brilliance are several factors. First and foremost, it shows us what is almost certainly a sufficient (though not a necessary) model of mind. There is no proof, and probably never will be, that there exist thought processes of which humans are capable and computers are not. This is a source of extreme consternation for many people–very like Darwin’s ideas were and, in some quarters, still are.
The reason why such proof will likely never be forthcoming is because it would involve demonstrating that the brain or the mind is capable of things that a Turing machine is not–and a Turing machine is a universal machine in the sense that a Turing machine can perform any computation that can be thought of algorithmically, involving finitely many steps.
Turing has given us a theoretical model not only of all possible computing machines, which launched the age of computing, but a device capable of thought at, as it were, the atomic level of thought. I don’t really see that there is any reasonable alternative to the idea that our brains must function as information processing machines. The universality of Turing’s machine is what allows it to encompass even our own brains.
Additionally, another reason to rank Turing’s idea very high is that, mathematically, it is extrordinarily beautiful, drawing, as it does, on Godel’s marvelous ideas and also those of Georg Cantor. Turing’s ideas are apparently the culmination of some of the most beautiful mathematics ever devised.
Darwin’s ideas place us in the context of “deep history”, that is, within the long history of the planet. And they put us in familial relation with every living thing on the planet in a shared tree of life. And they show how the diversity of life on our planet can theoretically emerge via evolution and natural selection.
Darwin’s ideas outline a process that operates in history to generate the tree of life. Turing’s ideas outline a process that can generate all the levels of cognition in all the critters thought of and unthought. Darwin gives us the contemporary tree of life; Turing gives us the contemporary tree of knowledge.
Here are links to the blog posts, so far, in Computer Art and the Theory of Computation: