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Re: [ontolog-forum] The class of the planet Venus

To: "[ontolog-forum]" <ontolog-forum@xxxxxxxxxxxxxxxx>
From: Ed Barkmeyer <edbark@xxxxxxxx>
Date: Thu, 12 Jul 2012 16:45:44 -0400
Message-id: <4FFF3778.10307@xxxxxxxx>
Ah yes, this is the problem of what "model" means in what context.
I think I was misled by John's terminology "model of the world".    (01)

I fully agree that the semantic model for a logic language is a set of 
things in the "world of interest".
And if what John meant by a "model of the world" is a collection of 
things and states taken to be a domain of discourse, then I withdraw my 
complaint.  (I tend to use the word "world" with that meaning, precisely 
because ... )    (02)

The community I work in understands "model" to mean an engineering 
model, and "model of the world" to mean a representation of the state of 
the actual or intended world in terms of some specific 
conceptualization.  That is why I said that a model of a building is not 
a building.  An engineered artefact is the result of a 
conceptualization.  A data or knowledge base that is a "model of the 
world" is an organized repository of information about some "world" (or 
in logic terminology, some "model").  In a semantic model for a civil 
engineering ontology, the actual building is an element of the model, 
and a "building model" might also be.    (03)

So, I apologize to all for creating confusion by misuse of terms, and 
specifically to John, for miscasting his intent.    (04)

-Ed    (05)

Edward J. Barkmeyer                        Email: edbark@xxxxxxxx
National Institute of Standards & Technology
Manufacturing Systems Integration Division
100 Bureau Drive, Stop 8263                Tel: +1 301-975-3528
Gaithersburg, MD 20899-8263                Cel: +1 240-672-5800    (06)

Chris Menzel wrote:
> On Thu, Jul 12, 2012 at 11:03 AM, Ed Barkmeyer <edbark@xxxxxxxx 
> <mailto:edbark@xxxxxxxx>> wrote:
>     John F Sowa wrote:
>     >   4. The distinction between intensions and extensions can be used
>     >      for individuals as well as for sets, relations, functions, and
>     >      classes.  The basic point is that the extension is something
>     >      in the world (or a model of the world), and the intension is
>     >      a definition that is used to characterize and identify the
>      >     thing or things in the world (or some model of the world).
>     ...
>     I do wish John had avoided the insertion of the parenthetical
>     expressions in the above, because they weaken, perhaps to the point of
>     confusing, his thesis.
>     The reason I object to John's parenthetical references to "models
>     of the
>     world" is that most "models" in this sense are intrinsically
>     intensional. The artefacts in models are /constructed from/ the
>     intensions, and two such artefacts may indeed be different even
>     when the
>     thing they are models of is the same.  A model of a building is not a
>     building.  Two different models of the same building are different
>     things, each conforming to a particular characterization of the
>     building, whether the building itself exists or not, and in fact,
>     whether or not the building in being actually possesses those
>     characteristics.  (This is a critical idea in Herbert Simon's famous
>     work "The Sciences of the Artificial", and in some of Ted Goranson's
>     work.)  So it is in fact very difficult to argue that two
>     conceptualizations of model elements are 'coextensive'.  The model
>     element is a manifestation of the conceptualization, not the extension
>     of it.  I would go so far as to say that a model element is a Frege
>      Zeichen -- a sign/symbol for the intension (Sinn).
> I'm afraid that, for the first time I can recall, I have to disagree 
> with Ed here. For there is absolutely no reason why the elements of a 
> semantical model of a logical language (including most any KR 
> language) cannot be exactly the entities we "intend". Indeed, such 
> "intended" models are typically exactly what we wish to be talking 
> about when we use the language in question: The natural, intended 
> model of the language of arithmetic contains the natural numbers; the 
> natural model of an ontology for a manufacturing system might well 
> contain exactly the actual machines on the assembly line. Furthermore, 
> I must say that I am not sure what Ed means when he says that models 
> are "intrinsically intensional" or that they are "constructed from 
> intensions". In the theory of models for logical languages, this is 
> just not the case; the notion of an intrinsically intensional entity 
> is simply not a part of the theory. Moreover, I am not sure we've got 
> enough of a grip on the notion of an intensional entity beyond the 
> idea that that distinct intensions can have the same extensions. This 
> is represented in possible world semantics by defining extensions as 
> functions from worlds to extensional entities of one sort or another. 
> It is represented in the semantics of Common Logic simply by 
> distinguishing between semantic objects and their extensions, but 
> there is not much more to be said about the nature of intensions than 
> that — formally, at any rate.
> So, while I think the distinction between intension and extension is 
> certainly legitimate, I am skeptical of their introduction into the 
> modeling domain in any sense beyond the well-understood (and 
> ultimately extensional, from a purely formal perspective) 
> representations found in possible world semantics or Common Logic.
> -chris
>    (07)

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