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Re: [ontolog-forum] Fwd: [New post] The Newest from SOA: The SOA Ontolog

To: "[ontolog-forum] " <ontolog-forum@xxxxxxxxxxxxxxxx>
From: Christopher Menzel <cmenzel@xxxxxxxx>
Date: Fri, 24 Dec 2010 13:54:10 -0600
Message-id: <70AD759A-E8C0-4476-8EC5-953364E2D606@xxxxxxxx>
On Dec 24, 2010, at 9:58 AM, Patrick Durusau wrote:
> ...My point is that useful ontologies are not limited to those constructed 
>based on formal logic and avoidance of modeling mistakes.     (01)

So, if I understand you, Patrick, your point is that     (02)

  (D) There can be useful models that are either (a) not based
      on formal language or (b) contain modeling mistakes.    (03)

Before addressing that, let's first be sure that we mean the same thing by 
"based on formal logic."  By that I certainly don't mean an ontology that is 
written in an explicitly formal language like CLIF.  There are, in particular, 
some very nice, user-friendly graphical languages that are entirely rigorous.  
To say that a language for constructing ontologies is based on formal logic is 
only to say that the language has a sound logical foundation -- specifically, 
the syntax of the language must be clearly defined (so that well-formed 
constructs can be clearly distinguished from ill-formed) and the basic 
constructs of the language must have a rigorous semantics so that assertions in 
the language can be meaningfully interpreted. (Both are necessary, in 
particular, if the ontology is going to be subject to any sort of useful 
automated reasoning.)  A well-designed tool like Protege will simply 
incorporate those logical foundations into the tool itself and a user will 
adhere to them simply in virtue of using the tool.  So to say ontologies must 
be "based on formal logic" is only to say that the representation language of 
the ontology meets strike me as entirely minimal standards of rigor and 
coherence.      (04)

Given this, part (a) of your thesis (D) is that there are, or at least can be, 
useful ontologies such that either it is not clear what is a well-formed 
construct of the language and what isn't, or it is not clear what the meanings 
of its basic constructs are.  I wouldn't want to go so far as to say such an 
ontology could not be useful in some very limited way; perhaps in a small 
organization in which people can clarify what the ontology is supposed to mean 
with verbal explanations and where there is no need for the ontology to be 
shared by others outside of that small setting.  So let me revise my claim to 
be that ontologies "not based on formal logic" are useful at best in some very 
limited setting.    (05)

As for part (b) of (D), I have to say I am nonplussed.  What do you have in 
mind?  Obviously, it is unlikely that any large ontology with be completely 
free of modeling errors, but surely the usefulness of an ontology is inversely 
proportional to the extent of its errors.    (06)

> I happen to agree that construction of logic based ontologies requires
> more than "...a clear head, a bit of common sense, and a copy of
> Protégé." Having said that, I would not exclude ontologies developed
> without a formal logic basis from being ontologies.    (07)

Oh, that's a different claim.  I myself would have no problem saying there are 
ontologies that are not based on formal logic in the sense above. I would 
simply say, once again, that they are, at best, marginally useful or, at worst, 
incoherent.    (08)

Chris Menzel    (09)

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