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Re: [ontolog-forum] Levels

To: "[ontolog-forum]" <ontolog-forum@xxxxxxxxxxxxxxxx>
From: Christopher Menzel <cmenzel@xxxxxxxx>
Date: Thu, 15 Feb 2007 11:54:58 -0600
Message-id: <AA003C51-9952-4119-B388-7C306B7C1EB1@xxxxxxxx>
Pat, I think it will save you some work (and perhaps some  
frustration :-) if you read this whole msg before starting to respond:    (01)

On Feb 14, 2007, at 1:11 PM, Pat Hayes wrote:
>>>> then it seems to me that this confuses a
>>>> mechanism for saying what (some of) the axioms of an
>>>> ontology are with the ontology.
>>>  Why do you call this "confuses"? The assertion of
>>>  what some of the axioms are can be part of the
>>>  theory.  You seem to be insisting on a 'levels'
>>>  distinction here which I fail to see the reason
>>>  for (and plenty of reasons to reject.)...
>> Here's why I said the two are being confused.  Intuitively,
>> an ontology is about a certain domain, say, faculty and
>> admin at TAMU.  The relevant objects, properties and relations
>> in that domain are indicated by the names in one's ontology
>> language.  If one of the names is now a URL pointing to your
>> ontology at IHMC, then, on this intuitive understanding of
>> what an ontology is, your ontology at IHMC becomes
>> part of the *subject matter* of my faculty and admin ontology.
> If by 'subject matter' you mean that it is in the universe of  
> discourse, yes. But all sorts of things are in the universe of  
> discourse of any reasonably complicated assertion: your TAMU  
> example may well refer to numbers, dates, time-intervals,  
> publications, etc.    (02)

Of course -- those things might well all end up being among the  
things we find in the faculty/admin structure at Texas A&M when we  
write our ontology.  But surely YOUR ONTOLOGY (containing, we've  
supposed, useful information about higher-level administrative  
structures) is not.  That would be no different than asserting that  
the entire faculty/admin ontology is itself part of its own subject  
matter.  It is the CONTENT of your ontology, not the ontology itself,  
that becomes part of the overall ontology's subject matter.  Your  
ontology just happens to be where we find that content, but, unlike  
the other entities you mention, it is *not* among the objects,  
properties, and relations that are constitutive of the faculty/admin  
structure at Texas A&M.    (03)

>>  That seems wrong;
> I have no idea what you mean by "wrong". It seems to me to simply  
> be a fact, and follows from the model theory in the specs. And I  
> have absolutely no intuitive problem with it (I suspect because I  
> don't take the notion of "subject matter" as being as salient as  
> you apparently do.)    (04)

I think perhaps that is the nub of our disagreement -- though I'm not  
sure we've distinguished carefully between that intuitive idea and  
the semantic quibble about what "formal ontology" should mean; see  
last paragraph below.    (05)

>> So, while I am most certainly not "insisting" on it,
>> I am indeed suggesting that there is an important conceptual
>> distinction to be made here between "object-level" statements
>> concerning the entities, types,  and relations of interest in
>> the ontology and "meta"-statements about the ontology itself,
>> notably statements about where certain object-level statement
>> can be found on the web.
> And I want to strongly deny this conceptual distinction. I think it  
> reflects a pre-Web way of thinking about knowledge. And PLEASE  
> don't say that imports is meta-level, even in scare quotes.    (06)

As wise as you are in the ways of the web, I cannot follow you here.   
While, logically, you are quite right -- "imports" statements are  
object language statements with a clean semantics -- there is still a  
distinction to be made between ontologies, qua things in their own  
right, and their content, just as there is between names and their  
referents.  Ontological engineering has taken hold in part because  
people have exceedingly strong intuitions about *what there is*, what  
they talk about, in their various domains.  If I ask a seasoned  
administrator about the things they talk about vis-a-vis faculty and  
admin structure at Texas A&M, your ontology itself will not be among  
those things; once again, the content of your ontology will be.  I  
think that is an intuition worth preserving, and I don't find it in  
the least bit "pre-Web".  What would be pre-Web is to fail to realize  
that one can exploit open networks to incorporate remote content like  
your ontology into one's own ontology, with all the attendant  
practical and semantic benefits.  But I frankly think that it will  
likely lead to confusion on the part of ordinary users to say that,  
anytime a remote ontology is imported the ontology itself, rather  
than its content, suddenly (and entirely accidentally) becomes  
elevated to a fully-fledged element of my domain.    (07)

>> But really, we're simply involved in a quibble here.  The  
>> important (?) thing is to have a consistent understanding of what  
>> an formal ontology is.
> But I think it is a very important quibble. The fact that imports  
> statements are genuine assertions, not some kind of 'markup  
> metalevel' that can be handily ignored to protect the innocent  
> intuitions, is not merely a quibble: it is central to the SWeb  
> vision. So, I insist, imports statements *are* part of a formal  
> ontology.    (08)

I am of course as enthusiastic about that vision as anybody.  And you  
are transmogrifying my argument into a strawman if you characterize  
me as saying that imports statements are not genuine assertions and  
can be "handily ignored".  I am only saying that there is a  
distinction that merits preservation between an ontology and its  
content, just as there is a distinction between names and things  
named -- I'd be *perfectly happy* with a definition of "formal  
ontology" that includes the imports statements; and in fact, upon  
reflection, I find myself rather persuaded that we should so define  
them, given the OWL precedent.  I would simply argue that there  
should also be recognized something like "the logical theory of O"  
for a given ontology O, which comprises the DOMAIN axioms found  
directly in O together (recursively) with all those domain and upper- 
level axioms that are pulled into O by imports statements.  If I'm  
entirely alone here, fine, but I really do think this is important.    (09)

-chris    (010)

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