On May 1, 2008, at 14:21 , Pat Hayes wrote:
At 1:41 AM -0400 5/1/08, Bill Andersen wrote:
Here we go again...
On Apr 30, 2008, at 18:08 , Pat Hayes wrote:
> At 8:21 PM +0200 4/30/08, Cati Martínez wrote:
>> I'm new in the Ontology world, and maybe it has been already
>> discussed, I'm asking me the question if everything implemented in
>> OWL language can be considered an Ontology. I guess that it's not so,
>> but it is difficult for me to say when we can say that it is or not.
> The term 'ontology' has no definition precise
> enough to answer that question. Myself, I'd be
> inclined to say yes, anything in OWL is an
> ontology. Certainly one would not expect any OWL
> tool or engine to start distinguishing between
> 'real ontology OWL' and 'mere OWL'.
I admit the problems with coming up with anything close to a
definition of the term "ontology" and of course no machine is going to
be able to tell the difference. But your position above equates (the
referents of) "ontology" with "theory expressed in a formal
Yes, exactly. Can you suggest any principled reason why we should not do this?
Or at least it makes them coextensional if we want to put
that fine a point on it.
This is at least a very permissive version of Quine's position in "On
what there is".
What has Quine got to do with it? We aren't using 'ontology' in Quine's sense. In any case, the only practical position to take on existence and quantifiers is completely at odds with Quine: to be (ie to be real, in the actual world) is NOT to be the value of a bound variable. We have to be able to quantify over possibilia, in actual ontological practice. One of the lessons of the IKRIS project is that treating quantification into "opaque" contexts by introducing rigid names for possibilia, rendering the contexts transparent, is a much better approach than the more philosopher-sanctioned technique of giving names in opaque contexts a de dicto reading. So, maybe Quine was right for philosophy, but he most certainly wasn't right for ontology engineering.
I don't think Quine would have bestowed the honor of
existence on a lot of the referents of terms introduced in most of
what are called "ontologies", written in OWL or not -- he reserved
that for objects revealed by best practice in science. Thus his
epistemic motivation ought to appeal to you. But certainly the
following would not count for Quine and hopefully not for you:
<a rdfs:subclassOf b>
That's a legal OWL theory
No, its not. The subject and object have to be legal URIreferences. This is:
extp:a rdfs:subclassOf extp:b .
C'mon. That is irrelevant trivia and immaterial to the point I was making. Maybe someone at W3C cares, but I don't.
And yes, that is an ontology. Its not a very interesting ontology, but I see nothing whatever to be gained by trying to give criteria to distinguish 'mere assertions' from 'real ontologies'.
I did not advocate that position. Others did; I stayed on the fence.
This kind of distinction is impossible to make precise, cannot be based on anything other than intuition or prejudice, and in any case is not the slightest use. So, to hell with it. To ignore it is good engineering, good methodology and (I submit) good philosophy. I propose to ignore it, and urge others to do the same.
The problem I have with the use of the term "ontology" in the way you suggest is that it is thereby just a synonym for perfectly useful and well-understood technical terminology that we already have. Namely "logical theory".
The only reason I can see for the use of the term "ontology" in this connection is to increase the chances of winning funding from people who still attach mystic significance to the term "ontology" that they would not to "logical theory"
Surely you can't be in favor of introducing a new term that does no more and no less work than established terms of art in logic and automated theorem proving, can you?
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