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Re: [ontolog-forum] Reality and semantics. [Was: Thing and Class]

To: "[ontolog-forum] " <ontolog-forum@xxxxxxxxxxxxxxxx>
From: Pat Hayes <phayes@xxxxxxx>
Date: Wed, 17 Sep 2008 21:17:49 -0500
Message-id: <6F99883C-3211-4620-82F5-DBDB4FAA13DE@xxxxxxx>

On Sep 17, 2008, at 12:30 PM, Len Yabloko wrote:


As you concluded this very intellectually challenging debate with John, and two of you finally agreed to disagree, - let me see what it means for software developer like myself.

Sure.  But might I ask, what kind of software you develop? How does it - the software - relate to ontologies? 

On Sep 16, 2008, at 7:30 PM, John F. Sowa wrote:

Pat and Chris,

JFS>>> A Tarski-style model is a set of entities and a set of
relations among those entities.  Those entities and relations are
*approximate* representations of aspects of the world according to
some ontology.

CM>> Sure.  Every model leaves out information that is found in the
piece of the world that the model represents.

PH> Represents? Ouch. If there is a 'represents' relationship between
models and reality, then all our axiomatic ontologies must be given
a two-stage semantics, in which model theory describes the first
stage of interpretation, yielding a new kind of 'representation'
which then needs another, presumably different, semantic theory to
relate it to actuality.

Welcome to reality.  As George Box said and I quoted in my previous
note, "All models are wrong, but some are useful."

Its not reality. In fact, we all manage extremely well with a single-
layered semantics called model theory.

Most of software developers would probably say: "we all manage extremely well without it", and many of us might add "without any semantics at all".

I very much doubt that. I don't think it is possible write any nontrivial software without having some command of semantics, often a fairly precise one. Of course it may not be expressed mathematically or in terms of model theory by those who use it, but nevertheless it has to be there. And when one looks at the amount of effort devoted to getting software well-structured in one sense or another, the importance of a precise semantics seems to loom increasingly large, at least it seems so from what I have read. Certainly many of the common mistakes made by beginning developers of RDF and OWL systems stem directly from a failure to grasp the semantics of these formalisms. 

Few of us may note that we only need operational semantics. But none of us will say what you said. So I don't know who do you refer to as "we all", and what do you call to "manage extremely well".

I was meaning to refer to people who seek to give semantic theories for assertional formal languages used in ontologies, actually, rather than software developers. 

This two-level idea is a  
chimera, and an intellectual dead end.  You have argued for the idea,  
but do you have even an outline or a sketch of what the second, model-
to-reality, semantic theory looks like? In order to give it, you need  
to somehow describe reality mathematically. In full generality. OK,  
I'm all ears.

I would say that most people manage extremely well without "describing reality mathematically".

In a broad sense of 'mathematical', I would say that virtually all software describes reality mathematically. But in this context, we were referring to (hopefully reasonably precise) semantic theories, which are pretty much required to be mathematical, in the sense that they are couched in sufficiently formal language as to enable one to prove theorems in them. 

In fact most believe that it is impossible to do so.

PH> Not only has this project never been undertaken to completion,
I don't think its needed.

That is why 20th century analytic philosophy has trivialized the
subject to the point where the total number of bookshelves devoted
to philosophy in a large Barnes & Noble store is equal to the
number devoted to Sudoku puzzles.

This comment is completely off the wall.

I think it is literally "off the wall" of any profitable book store. Or else it would quickly go out of business. Because the semantics you are finding so useful are actually totally useless for real world that they..., should I say represent ?

This is such rubbish that I won't even try to sketch a response. Which  
*semantic* problems are being ignored?

I'd like to ask what *semantic* problems are NOT ignored by software community. Certainly Semantic Web community ignores most of them beginning with most basic identity problems.

Well, do tell us what these semantic problems are. Give an illustrative example. 


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