Thanks John. I guess that was the problem I was seeing with the
definition of a "stretch" of a river in the Protege example but I had
not thought to extend it to river itself. I was not aware of the
pedigree of this problem, so that was very helpful. (01)
This means that when setting out to define anything formally, one has to
be aware of when one is modelling some discrete thing such as a pump or
an elephant, and when one is modelling human perceptions of things. The
latter will always need to be referred to in business ontologies at some
point, though I imagine in most cases there would be a legal definition
for things that are of relevance to any business (legal being IMHO one
of the primary sources of meaning to a business). So for example the
Thames migh be defined legally as that which comes under the
jurisdiction of the UK's Environment Agency and is defined by them as
the Thames (since they are responsible for a number of watercourses).
OK, bad example as that's the non-tidal Thames, but the tidal Thames is
in many ways a legal black hole. (02)
In practical terms, if you are building an ontology for some genuine
business purpose then I imagine the appropriate legally-grounded
definitions will suggest themselves. So licences for boats will refer to
the jurisdictions responsible for licensing on those watercourses, while
a booking system for pleasure cruises will refer to local, arbitrarily
defined "stretches" identified with reference to fixed landmarks like
locks and jetties (rather than a legal definition). To me, this is one
of the challenges of trying to mandate some "global" ontology without
reference to the people who already own the specific business problems. (03)
As you mention later, the trouble with the legal grounding of semantics
is that there are many boundary cases that are only resolved in a court
of law. So the legal grounding of meaning, while appropriate for
business semantics, is itself an imprecise mechanism in which a given
concept is identified, but that concept may iself be subject to future
refinement. Well, the computer system can't be expected to know more
than the business itself, so as long as the system has an ontology which
is in line with what the business "knows" then it won't add any mistakes
of its own. Presently, the computer programmer can bring in their own,
wholly ungrounded assumptions about the world they are dealing with. (04)
A lot of food for thought there, for whoever is setting out the
ontological commitment of a given ontology. Perhaps a good ontology
development method should formally recognise and deal with the
distinction between human perceptual constructs and the more tractable
kinds of thing. I would certainly want to see the issues you have come
up with (and much other philosophical knowledge) reflected in a formal
ontology development method so it doesn't rely on engineers like me
having read all the philosophy. (05)
John F. Sowa wrote:
> Mike and Mitch,
> I would like to comment on the following point:
> MB>> According to that definition the Okavango is not a river.
> MH> The Okavango surely is a strange kind of river.
> > Do you really expect to hold natural language to the same
> > strictness standards as formal ones?
> This question has nothing to do with the differences between
> natural languages and formal languages. It is the result
> of trying to map a continuously variable world to a discrete
> set of labels (i.e., words, terms, symbols, concepts, signs).
> As a continuous fluid (at least to a degree far below human
> perception), there is a continuous range of ways that water
> can flow across a surface. For various purposes, people label
> those ways of flowing that happen to be significant for their
> interests. The way they group them and label the groupings
> depends on what they consider important in their environment.
> The kind of language, natural or artificial, is irrelevant.
> This is a commonly discussed issue in philosophy:
> Immanuel Kant:
> "Since the synthesis of empirical concepts is not arbitrary
> but based on experience, and as such can never be complete
> (for in experience ever new characteristics of the concept
> can be discovered), empirical concepts cannot be defined.
> "Thus only arbitrarily made concepts can be defined synthetically.
> Such definitions... could also be called declarations, since in
> them one declares one's thoughts or renders account of what one
> understands by a word. This is the case with mathematicians."
> Wittgenstein's *family resemblances* :
> Empirical concepts cannot be defined by a fixed set of necessary
> and sufficient conditions. Instead, they can only be taught by
> giving a series of examples and saying "These things and everything
> that resembles them are instances of the concept."
> Waismann's *open texture* :
> For any proposed definition of empirical concepts, new instances
> will arise that "obviously" belong to the category but are
> excluded by the definition.
> As Kant observed, precision depends on the kind of concept, not
> on the kind the language used to define the concept.
> As Waismann observed, if you state a precise definition for an
> empirical concept (such as 'river'), you will simply exclude
> many reasonable examples, such as the Okavango River.
> John Sowa
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