>hi,
>in this thread and in the "Ontology and methodology" thread the category
>ROLE was mentioned several times.
>I am wondering what a role is ontologically? What are the
>super-categories of ROLE? In one of the extensions of DOLCE, a role is
>considered a non-physical social object. (01)
I think that is a rather special interpretation of 'role'. It had
better be, as the idea of 'social object' makes no sense at all in
many domains of application. (02)
One of the problems of DOLCE is that its authors (as they candidly
admit) were trying to make an ontological framework for 'common
sense' knowledge, apparently under the impression that everyday
knowledge of this kind is fundamental, or at any rate reveals
fundamental ontological distinctions. This idea is however very
debatable, and I think likely to be false. Everyday common sense is
simply one more area of expert specialization, like protein folding
or cell biology: we don't think of it that way only because all
competent adults are experts, like chess grandmasters in this
particular domain. But it is just as peculiar and idiosyncratic as
any other, and ontologies designed for it don't automatically
transfer to other domains. (03)
The difficulties that folk have with these ideas, and knowing when to
make the distinctions that seem so obvious to others (but which still
others put in slightly different ontological places), illustrate
perfectly what I view as a badly motivated ontological distinction.
Someone has found this distinction useful for some purposes. Others
have cleaned it up and elevated it to a central or fundamental
distinction. All good work, and I don't mean to disparage any of it:
but it does not follow that this distinction is universally useful or
even universally appropriate. It might be more trouble than it is
worth for many ontological purposes. Very strict or absolute
high-level distinctions often are more trouble than they are worth.
If you have to keep asking yourself how to apply the distinction
appropriately, and you always seem to be in a grey area, then the
game is likely not worth the candle. (04)
>Roles seem helpful in terms of achieving taxonomically "clean"
>ontologies in the sense of OntoClean (Welty, Guarino).
>Yet employing the category ROLE in ontology engineering seems to be
>problematic since many (most) categories used in domain ontologies would
>suddenly have ROLE as super-category. What do I get wrong here?
>Take for example an object that is identified as being a chair. I guess
>in many ontologies, CHAIR would be classified as sub-category of
>PHYSICAL OBJECT. This is, any entity that is identified to be a chair is
>also a physical object.
>However, in the context of the previous mails, one could claim that a
>chair is identified being a chair by affording sitting on it; by the
>role it plays. If a certain entity which was previously identified as
>chair, is never used again for sitting but only for, say, a step for
>changing light bulbs, it stops playing the role of being a chair and is
>hence only playing the role of a step for changing light bulbs (?). (05)
It would still be a chair, however (or at least one could reasonably
claim this.) We would refer to it that way, and it would be listed
that way in a product catalog. I have a screwdriver that I bought to
be a paint-can-opener and have always used it for the purpose;
nevertheless, it IS a screwdriver. (06)
This is a very, very old debate in philosophical ontology, by the way. (07)
>Compare this to an employee being fired. The person does not loose its
>ability of playing the role of an employee, (08)
Not the ABILITY, which is a modal notion, but he or she does cease at
that firing moment to BE an employee. They take on a new role for
government purposes, of being employable but unemployed. (09)
> yet the certain entity is
>not classified as employee anymore.
>Why should a physical object, that is never used for sitting be
>considered a chair? (010)
Becasue being a chair isn't a SOCIAL role, maybe? (011)
Pat (012)
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