John, (01)
I think I could construct a logically consistent theory that is
nonsensical. Indeed it might be useful in some far possible world, but
one nowhere near close to our own. In fact, one might even consider it
the mission of science to find among a potentially infinite number of
(and dare I say consistent) theories about the world, the best or right
ones (where "best" means something like fully descriptive of the
domain, predictive, even explanatory, most concise, and bridging well
to other known theories; I know this gets us into philosophy of
science)? (02)
And of course, one can vary the logic too, so I guess one has to always
say "consistent in the logic used", and define consistency. And there
are formalizations of so-called impossible worlds. (03)
Although mathematical theories are abstract, are they not a part of the
world? By part of the world, I don't necessarily mean empirically
determinable (though even this can beg the question). (04)
So I am not convinced that (ontology = logical theory) only. (05)
Thanks,
Leo (06)
_____________________________________________
Dr. Leo Obrst The MITRE Corporation, Information Semantics
lobrst@xxxxxxxxx Center for Innovative Computing & Informatics
Voice: 703-983-6770 7515 Colshire Drive, M/S H305
Fax: 703-983-1379 McLean, VA 22102-7508, USA (07)
-----Original Message-----
From: ontology-summit-bounces@xxxxxxxxxxxxxxxx
[mailto:ontology-summit-bounces@xxxxxxxxxxxxxxxx] On Behalf Of John F.
Sowa
Sent: Thursday, January 25, 2007 11:04 AM
To: Ontology Summit 2007 Forum
Subject: Re: [ontology-summit] Defining "ontology" (08)
Leo, (09)
I think that we agree about the basic issues, but it is
very hard to set any limits on the domain: (010)
> Indeed, I would say an ontology is a logical theory AND
> purports to be about the real world. I can develop a
> nonsensical logical theory, for example. (011)
For example, all mathematical theories are purely abstract,
and they could be applied to the real world or anything else
imaginable. And any plans for something that does not yet
exist (e.g., the next new airplane by Boeing or Airbus) are
about an imaginary entity that does not yet exist, but it might
or might not exist at some indefinite time in the future. (012)
And once you allow ontologies for hypothetical devices, virtual
worlds, arbitrary mathematical structures, and hypothetical
scientific theories, it is hard to exclude anything else. (013)
Therefore, I would propose the following definition: (014)
A formal ontology is a consistent theory expressed in some version
of logic that defines the types, relations, and functions that
characterize the entities of some domain, which may be concrete
or abstract, real or virtual. (015)
The requirement of a consistent theory rules out nonsense whose
existence is impossible even in a virtual world, but it does
allow worlds whose laws may be very different from what we
currently consider "physics". (016)
For example, Alice's Wonderland has laws that are different
from anything we experience in the real world, and I doubt
that those laws are globally consistent. But it may be possible
to simulate a virtual world described by a global theory that
is defined as a disjunction of locally consistent theories
for the various episodes in Alice's adventures. (017)
John (018)
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