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One approach to the upper ontology, or any ontology really,
is to accept that it is, like law, an artifice. It works as
well as it works when it works and that is as well as it will
work. Like your car, it gets a job done and when it doesn't,
you or someone else can fix it.
The question of the semantic web is the golem problem: how
much power and authority will you give the artifice over your
choices? Otherwise, don't mistake a tool for the truth of
the results of using the tool. A computer doesn't know how
to add 2 + 2. It can be used to simulate that operation and
give a repeatable result. If 2 + 2 = 4 for an acceptable
number of uses, it is a useful tool. If you hit the one
context in which that isn't true, it fails. So understand
in advance what you are committing to and what the bet is.
An interesting question might be, when is an ontology expressing
something non-trivial? Where there are doubts about the value
of the semantic web, they are related to that question. The
cost of an expert system proved to be very high for the
utility it provided over a deliberately limited domain.
The assumption seems to be that some of the scaling magic
of the WWW will be obtained for the Semantic Web, but again,
networks scale precisely because they are NOT meaningful.
So this bet may not be a good one.
Treat ontologies like law: to be useful, law must be
testable or enforceable. Thus the notion of commitment
to rule by law and to an ontology (see Thomas Gruber). In
one view one might say, an ontology is a computable means
for expressing a precedent. Expressing and applying a
precedent is a matter of judgement, not truth. It is
also useful to inquire of how often you will find a
system useful based on the frequency with which it halts
and asks you a clarifying question, and the value in
terms of work when it does that? Interupts are expensive.
From: Irene Polikoff [mailto:firstname.lastname@example.org]
Yes, this is exactly right. Semantic Web is all about working with simple
unitary ontologies and having software agents go at them.
I don't think you are missing anything. One of the motivations for common
"upper" ontologies is that you support the interoperability of your
ontologies by maiking them all consistent with the UO. So this could be a
solution, but I have difficulty believing in the feasibility of making this
happen, although there are people who swear by it. I know of some work on
reasoners that manage contexts, so that you don't have to import all of your
foreign ontology to do reasoning, but this still has the issue of how one
knows it is consistent when you do.