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C00002 00002	meta[e81,jmc]		Comments on Stallman's META paper
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meta[e81,jmc]		Comments on Stallman's META paper

1. Non-monotonicity doesn't prevent a system from being
recursively enumerable.  If the opportunities for default
reasoning at any point in the argument and the requirements
for taking back previous results are both effectively
computable, then the set ofstates of belief are
recursively enumerable just as is the set of theorems
of an ordinary theory.  The difference is that the set of
all sentences that might be derived is not so interesting
as in conventional logic.  Since some are incompatible with
others, the important thing is the set of states of belief.
I think mathematician will be interested in non-monotonic
systems once they get used to the idea.

2. I still think one should say "non-monotonic reasoning" instead
of "non-monotonic logic".

3. I agree that one should consider possible states belief rather
than individual conclusions.  It is interesting, however, to ask
if the states of belief can't be regarded as single sentences by
taking conjunctions and whether this leads to interesting results.

4.