When Philosophers Encounter AI

Daedalus, Proceedings of the American Academy of Arts and Sciences, 117, 283-295, Winter 1988. Reprinted in S. Graubard, ed., The Artificial Intelligence Debate: False Starts, Real Foundations, MIT Press, 1988. Spanish translation, Gedisa, 1993; Polish translation forthcoming in Znak, Cracow.

When Philosophers Encounter Artificial Intelligence

Daniel C. Dennett
Center for Cognitive Studies
Tufts University
Medford, Mass 02155

How is it possible for a physical thing--a person, an animal, a robot--to extract knowledge of the world from perception and then exploit that knowledge in the guidance of successful action? That is a question with which philosophers have grappled for generations, but it could also be taken to be one of the defining questions of Artificial Intelligence. AI is, in large measure, philosophy. It is often directly concerned with instantly recognizable philosophical questions: What is mind? What is meaning? What is reasoning, and rationality? What are the necessary conditions for the recognition of objects in perception? How are decisions made and justified?

Some philosophers have appreciated this, and a few have even cheerfully switched fields, pursuing their philosophical quarries through thickets of Lisp. In general, however, philosophers have not welcomed this new style of philosophy with much enthusiasm. One might suppose that was because they had seen through it. Some philosophers have indeed concluded, after cursory inspection of the field, that in spite of the breathtaking pretension of some of its publicists, artificial intelligence has nothing new to offer philosophers beyond the spectacle of ancient, well-drubbed errors replayed in a glitzy new medium. And other philosophers are so sure this must be so that they haven't bothered conducting the cursory inspection. They are sure the field is dismissable on "general principles."

Philosophers have been dreaming about AI for centuries. Hobbes and Leibniz, in very different ways, tried to explore the implications of the idea of breaking down the mind into small, ultimately mechanical, operations. Descartes even anticipated the Turing Test (Alan Turing's much-discussed proposal of an audition of sorts for computers, in which the computer's task is to convince the judges that they are conversing with a human being) , and did not hesitate to issue a confident prediction of its inevitable result:

It is indeed conceivable that a machine could be made so that it would utter words, and even words appropriate to the presence of physical acts or objects which cause some change in its organs; as, for example, if it was touched in some spot that it would ask what you wanted to say to it; if in another, that it would cry that it was hurt, and so on for similar things. But it could never modify its phrases to reply to the sense of whatever was said in its presence, as even the most stupid men can do. Endnote 1

Descartes' appreciation of the powers of mechanism was colored by his acquaintance with the marvelous clockwork automata of his day. He could see very clearly and distinctly, no doubt, the limitations of that technology. Even a thousand tiny gears-- even ten thousand!--would never permit an automaton to respond gracefully and rationally! Perhaps Hobbes or Leibniz would have been less confident of this point, but surely none of them would have bothered wondering about the a priori limits on a million tiny gears spinning millions of times a second. That was simply not a thinkable thought for them. It was unthinkable then, not in the familiar philosophical sense of appearing self- contradictory ("repugnant to reason"), or entirely outside their conceptual scheme (like the concept of a neutrino), but in the more workaday but equally limiting sense of being an idea they would have had no way to take seriously. When philosophers set out to scout large conceptual domains, they are as inhibited in the paths they take by their sense of silliness as by their insights into logical necessity. And there is something about AI that many philosophers find off-putting--if not repugnant to reason, then repugnant to their aesthetic sense.

The whole paper is now available in Daniel Dennett, Brainchildren, Essays on Designing Minds, MIT Press and Penguin, 1998.


1. Rene' Descartes, Discourse on Method (1637), translated by Lawrence LaFleur (New York: Bobbs Merrill, 1960).