Dear John, (01)
> MW>>> ... and they are only consistent if they use the same upper
> >>> ontology (ontological commitments, core relations an categories).
> JFS>> That is false. Two low-level theories that have nothing in
> >> common are *guaranteed* to be consistent.
> MW> That is true but not useful. If there is no point of contact
> > between two ontologies, there is nothing to integrate.
> Actually, it can be very useful. A lower-level ontology that does
> not depend on some upper-level commitments could be compatible with
> many different upper levels. One example is an ontology for units
> of measure, which can be neutral about Newtonian mechanics, quantum
> mechanics, relativity, 3D, 4D, etc. (02)
[MW] When I have looked at that I have been forced to a different
conclusion, at least as far as 3D and 4D is concerned. The problem is that
most of these things are classes of individual, but in 3D and 4D the
individuals are different things, so the memberships are different, so the
meaning must be different. Now if the lattice can accommodate varying
meanings, then you may be ok. There are clearly at least analogous objects.
> Another example might be a body of laws and legal principles that
> has very little to say about physics. It too could be compatible
> with many different upper levels. (03)
[MW] See above. The problem is that any lower ontology must have an implicit
upper ontology, and it at least can't be both 3D and 4D or neutral to them. (04)
> When a legal case arises, it
> might be necessary to combine multiple lower level modules with
> a suitable upper level. Some of the previously disjoint modules
> would become linked when combined with an upper level. (05)
[MW] If they are not joined at a lower level (i.e. include some same
concepts) they would not become joined by an upper ontology, except in the
sense of being different parts.
> JFS>> The key point is that you should *never* try to merge two
> >> total ontologies.
> MW> That is false. It depends what you are trying to do. For example,
> > if you are replacing several small systems with a single large
> > system it would be very sensible to integrate the ontologies from
> > the small systems in developing the new system.
> I agree, but we were using different meanings for "total". I meant
> that you would never attempt to integrate a very large ontology like
> Cyc with another large ontology that also had a large upper level. (06)
[MW] I'm not sure about that either.
> But the lattice allows those large lumps to be modularized over time.
> Many of the lower level modules (microtheories) could be compatible
> with multiple upper-level commitments.
> JFS>> Instead, you only need to extract the parts that are necessary
> >> for the task(s) on which interoperability is required.
> MW> I would rather say that is the minimum you should do. In practice
> > I have found this can be significantly sub-optimal when that are
> > multiple such projects to be executed (as there usually are).
> I agree, but there are also other important cases. For example,
> Amazon.com forces the suppliers of books, electronics, and other
> products to use their low-level ontology for buying, selling, and
> shipping. That ontology has become a de facto standard for many
> suppliers and sellers. But it has very little commitment to the
> upper levels or to the details of the products that are being sold. (07)
[MW] None the less there will be an implicit upper ontology. It cannot be
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