JMC@SAIL.STANFORD.EDU (John McCarthy) (02/02/88)
1. The logic approach (which I follow). Understand the common sense world well enough to express in a suitable logical language the facts known to a person. Also express the reasoning methods as some kind of generalized logical inference. More details are in my Daedalus paper. 2. Using nano-technology to make an instrumented person. (This approach was suggested by Drexler's book and by Eve Lewis's commentary in AILIST. It may even be what she is suggesting). Sequence the human genome. Which one? Mostly they're the same, but let the researcher sequence his own. Understand embryology well enough to let the sequenced genome develop in a computer to birth. Provide an environment adequate for human development. It doesn't have to be very good, since people who are deaf, dumb and blind still manage to develop intelligence. Now the researcher can have multiple copies of this artificial human - himself more or less. Because it is a program running in a superduper computer, he can put in science programs that find what structures correspond to facts about the world and to particular behaviors. It is as though we could observe every synaptic event. Experiments could be made that involve modifying the structure, blocking signals at various points and injecting new signals. Even with the instrumented person, there would be a huge scientific task in understanding the behavior. Perhaps it could be solved. My exposition of the "instrumented man" approach is rather schematic. Doing it as described above would take a long time, especially the part about understanding embryology. Clever people, serious about making it work, would discover shortcuts. Even so, I'll continue to bet on the logic approach. 3. Other approaches. I don't even want to imply that the above two are the main approaches. I only needed to list two to make my main point. How shall we compare these approaches? The Dreyfus's use the metaphor "AI at the crossroads again". This is wrong. AI isn't a person that can only go one way. The headline should be "A new entrant in the AI race" - to the extent that they regard connectionism as new, or "An old horse re-enters the AI race" to the extent that they regard it as a continuation of earlier work. There is no a priori reason why both approaches won't win, given enough time. Still others are viable. However, experience since the 1950s shows that AI is a difficult problem, and it is very likely that fully understanding intelligence may take of the order of a hundred years. Therefore, the winning approach is likely to be tens of years ahead of the also-rans. The Dreyfus's don't actually work in AI. Therefore, they take this "Let's you and him fight" approach by babbling about a crossroads. They don't worry about dissipating researchers' energy in writing articles about why other researchers' are on the wrong track and shouldn't be supported. Naturally there will still be rivalry for funds, and even more important, to attract the next generation of researchers. (The connectionists have reached a new level in this latter rivalry with their summer schools on connectionism). However, let this rivalry mainly take the form of advancing one's own approach rather than denouncing others. (I said "mainly" not "exclusively". Critical writing is also important, especially if it takes the form of "Here's a problem that I think gives your approach difficulty for the following reasons. How do you propose to solve it?" I hope my forthcoming BBS commentary on Smolensky's "The Proper Treatment of Connectionism" will be taken in this spirit.) The trouble is "AI at the Crossroads" suggests that partisans of each approach should try to grab all the money by zapping all rivals. Just remember that in the Communist Manifesto, Marx and Engels mentioned another possible outcome to a class struggle than the one they advocated - "the common ruin of the contending classes".