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Re: [ontolog-forum] Ontology and methodology: roles

To: "[ontolog-forum]" <ontolog-forum@xxxxxxxxxxxxxxxx>
From: "John F. Sowa" <sowa@xxxxxxxxxxx>
Date: Wed, 21 Mar 2007 11:40:58 -0500
Message-id: <4601601A.3070706@xxxxxxxxxxx>
John,    (01)

That would be an excellent starting point:    (02)

JFS>> But I also believe that the confusion is based on ambiguities
 >> in the terms "individual" and "identity criteria".  Those
 >> words are an open invitation to creating new "individuals"
 >> and "identities" in very loosely defined circumstances.    (03)

JB> I agree. The goal must be to remove the "loosely defined
 > circumstances"...
 > and why limit to FOL, we should probably include as part
 > of the subject line metainformation concerning which logic
 > we are using in the post.    (04)

Several reasons for limiting it to FOL + metalanguage:    (05)

  1. First, that includes all the common logic-based implementation
     languages:  All the SemWeb languages, SQL and other database
     languages, all the logic programming languages, etc.    (06)

  2. There are many systems that use the phrase "higher-order logic",
     but every one I have seen is actually an implementation of
     either metalanguage or quantification over a fixed set of
     relations, as in Common Logic (which is the version of FOL
     I had in mind).    (07)

  3. The extension to metalanguage includes the IKL extensions to
     CL, which many people, including Doug Lenat, have subscribed
     to for supporting their systems.    (08)

  4. The prohibition of modal logic eliminates an enormous amount
     of confusing terminology about what is "necessary", "possible",
     or "essential".  This is not a restriction, because every such
     term can be defined at the metalevel by stating exactly which
     statement (i.e., law, principle, requirement, policy, etc.)
     causes the modal effect.  For more about how to do represent
     modality at the metalevel, see    (09)

     Laws, Facts, and Contexts:  Foundations for Multimodal Reasoning    (010)

     Worlds, Models, and Descriptions    (011)

I realize that the description logic people claim that DLs have a
modal effect, but that effect is *not* the result of the notation,
but of the way it's used:  the DLs in the T-box are assumed to have
greater "entrenchment" than the assertions in the A-box.  That has
the effect of making anything implied by the T-box to be "necessary"
relative to the A-box.  That can be stated at the metalevel.    (012)

JB> Seems to suggest that no problems are left as soon as one has
 > something in FOL plus some metalanguage.... does not seem to be
 > borne out much.    (013)

We'll never solve all the problems, but at least we can see what
is causing the hang-ups.    (014)

John    (015)

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