Dear Matthew, (01)
The kinds of applications I have in mind involve connecting a database
or knowledge base to de facto standards, such as the Amazon.com schema
for selling, shipping, etc. (02)
When they're selling a book or camera to some individual named
'Matthew West', they never dream of getting involved with issues
about 3D vs 4D ontologies. They just assume an underspecified
entity type Person, which is associated with identifiers for other
underspecified entity types: Address, Profile, CreditCard, etc. (03)
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. (04)
If systems based on your ontology cannot interact with the Amazon.com
databases, then you have a very serious problem. (05)
That is why I have said that upper level ontologies, when axiomatized
with too much detail can be *barriers* to interoperability. I am
all in favor of well designed upper-level ontologies. But they
have very few axioms. The axioms for detailed reasoning belong
where the reasoning is done: in the low-level microtheories. (06)
If you listen to the philosophers, they will tell you that identity
conditions are essential to ontology. But for interoperability, you
have to *ignore* the identity conditions. When you're linking your
DB or KB to the Amazon.com schema, you *never* want to worry about
whether a human being is a 3D or 4D entity or whether a vase is
identical to the lump of clay from which it is made. (07)
MW> 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. (08)
No. Many, if not most, ontologies that are important for
interoperability are neutral: The ontologies for units of measure,
for example, are completely neutral to 3d or 4d issues. The
typical databases of most businesses, including the Amazon.com
schema, don't require detailed reasoning about identity conditions. (09)
I would agree that identity conditions can be very important for
certain kinds of reasoning. For example, banks and other financial
institutions lose billions of dollars to cases of identity theft
and fraud. Those systems will have to extract a great deal of
data from typical business databases, but they will have extremely
detailed and complex identity conditions that go far beyond what
typical business databases use. (010)
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. (011)
They will certainly have many of the same concepts, but the
detailed definitions of Person, Place, Animal, Vegetable, etc.,
at the upper levels will be extremely underspecified. The
detailed reasoning, including the detailed axioms and definitions
will be done in the microtheories. (012)
Just think of all the DBs and KBs that have been implemented over
the past 40 years and are still in daily operation. They have
been interoperating with each other very well -- the entire
world economy depends on their interoperability. (013)
Those systems interoperate successfully *because* they don't
have detailed axioms and definitions. If you insist on putting
those details in the upper levels, you will destroy the world
financial system (or whatever is left of it). (014)
MW> None the less there will be an implicit upper ontology. It cannot
> be otherwise. (015)
I agree, and we have that already. I would suggest that you look
at a few legacy systems, such as the Amazon.com schema and other
widely used business databases. Their upper levels are almost
free of detailed axioms and identity conditions. (016)
And that is no accident. An underspecified upper level is a
*prerequisite* for interoperability with a wide range of
systems. (017)
John (018)
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