On 24/12/2010 2:54 PM, Christopher Menzel wrote:
> 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.
> So, if I understand you, Patrick, your point is that
>
> (D) There can be useful models that are either (a) not based
> on formal language or (b) contain modeling mistakes.
>
> 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.
>
It seems that you have just supported the original point by amplifying it.
> 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.
>
> 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.
> (01)
Given the extensive discussion in this forum about the meaning of some
very basic terms and expressions of very common concepts (even ignoring
the choice of English words associated with them which causes all kinds
of unintended meanings drawn into terms), it is unlikely that any
ontology will be devoid of fragments that some very smart people who
purport to be "Ontologists" find defective or simply wrongheaded.
The usefulness of an Ontology will be judged by the ROI that it provides
to the user community which in turn will be determined by how it
advances the solution of a real world problem.
Most ontologies will likely be in a constant state of revision as new
concepts and relationships become known and need to be added to the
ontology to remove some defect or increase its scope. Think of the
medical area or financial services where advances and new products are
daily occurrences.
That does not mean that an ontology is not useful. (02)
Ron (03)
>> 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.
> 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.
>
> Chris Menzel
>
>
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> (04)
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