- John Searle's refutation of the Berkeley answer that the system understands Chinese proposes that a person (call him Mr. Hyde) carry out in his head a process (call it Dr. Jekyll) for carrying out a written conversation in Chinese. Everyone will agree with Searle that Mr. Hyde does not understand Chinese, but I would contend, and I suppose his Berkeley interlocutors would also, that provided certain other conditions for understanding are met, Dr. Jekyll understands Chinese. In Robert Louis Stevenson's story, it seems assumed that Dr. Jekyll and Mr. Hyde time-share the body, while in Searle's case, one interprets a program specifying the other.
- Searle's dismissal of the idea that thermostats may be ascribed belief is based on a misunderstanding. It is not a pantheistic notion that all machinery including telephones, light switches, and calculators believe. Belief may usefully be ascribed only to systems about which someone's knowledge can best be expressed by ascribing beliefs that satisfy axioms such as those in McCarthy (1979). Thermostats are sometimes such systems. Telling a child, "If you hold the candle under the thermostat, you will fool it into thinking the room is too hot, and it will turn off the furnace" makes proper use of the child's repertoire of intentional concepts.
- Formalizing belief requires treating simple cases as well as more interesting ones. Ascribing beliefs to thermostats is analogous to including 0 and 1 in the number system even though we would not need a number system to treat the null set or sets with just one element; indeed we wouldn't even need the concept of set.
- However, a program that understands should not be regarded as a theory of understanding any more than a man who understands is a theory. A program can only be an illustration of a theory, and a useful theory will contain much more than an assertion that "the following program understands about restaurants." I can't decide whether this last complaint applies to Searle or just to some of the AI researchers he criticizes.
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