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Philosophy and artificial intelligence. These fields overlap in the following way: In order to make a computer program behave intelligently, its designer must build into it a view of the world in general, apart from what they include about particular sciences. (The skeptic who doubts whether there is anything to say about the world apart from the particular sciences should try to write a computer program that can figure out how to get to Timbuktoo, taking into account not only the facts about travel in general but also facts about what people and documents have what information, and what information will be required at different stages of the trip and when and how it is to be obtained. He will rapidly discover that he is lacking a science of common sense, i.e. he will be unable to formally express and build into his program ``what everybody knows''. Maybe philosophy could be defined as an attempted science of common sense, or else the science of common sense should be a definite part of philosophy.)

Artificial intelligence has another component which philosophers have not studied, namely heuristics. Heuristics is concerned with: given the facts and a goal, how should it investigate the possibilities and decide what to do. On the other hand, artificial intelligence is not much concerned with aesthetics and ethics.

Not all approaches to philosophy lead to results relevant to the artificial intelligence problem. On the face of it, a philosophy that entailed the view that artificial intelligence was impossible would be unhelpful, but besides that, taking artificial intelligence seriously suggests some philosophical points of view. I am not sure that all I shall list are required for pursuing the AI goal--some of them may be just my prejudices--but here they are:

  1. The relation between a world view and the world should be studied by methods akin to metamathematics in which systems are studied from the outside. In metamathematics we study the relation between a mathematical system and its models. Philosophy (or perhaps metaphilosophy) should study the relation between world structures and systems within them that seek knowledge. Just as the metamathematician can use any mathematical methods in this study and distinguishes the methods he uses form those being studied, so the philosopher should use all his scientific knowledge in studying philosophical systems from the outside.

    Thus the question ``How do I know?'' is best answered by studying ``How does it know'', getting the best answer that the current state of science and philosophy permits, and then seeing how this answer stands up to doubts about one's own sources of knowledge.

  2. We regard metaphysics as the study of the general structure of the world and epistemology as studying what knowledge of the world can be had by an intelligence with given opportunities to observe and experiment. We need to distinguish what can be determined about the structure of humans and machines by scientific research over a period of time and experimenting with many individuals from what can be learned in a particular situation with particular opportunities to observe. From the AI point of view, the latter is as important as the former, and we suppose that philosophers would also consider it part of epistemology. The possibilities of reductionism are also different for theoretical and everyday epistemology. We could imagine that the rules of everyday epistemology could be deduced from a knowledge of physics and the structure of the being and the world, but we can't see how one could avoid using mental concepts in expressing knowledge actually obtained by the senses.
  3. It is now accepted that the basic concepts of physical theories are far removed from observation. The human sense organs are many levels of organization removed from quantum mechanical states, and we have learned to accept the complication this causes in verifying physical theories. Experience in trying to make intelligent computer programs suggests that the basic concepts of the common sense world are also complex and not always directly accessible to observation. In particular, the common sense world is not a construct from sense data, but sense data play an important role. When a man or a computer program sees a dog, we will need both the relation between the observer and the dog and the relation between the observer and the brown patch in order to construct a good theory of the event.
  4. In spirit this paper is materialist, but it is logically compatible with some other philosophies. Thus cellular automaton models of the physical world may be supplemented by supposing that certain complex configurations interact with additional automata called souls that also interact with each other. Such interactionist dualism won't meet emotional or spiritual objections to materialism, but it does provide a logical niche for any empirically argued belief in telepathy, communication with the dead, and such other psychic phenomena as don't require tampering with causality. (As does precognition, for example). A person who believed the alleged evidence for such phenomena and still wanted scientific explanations could model his beliefs with auxiliary automata.

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John McCarthy
Fri Dec 21 12:19:53 PST 2001