Ontology is not a new concept. It is a century old concept, with roots from philosophy. However, the Semantic Web has popularised this concept (so many are forgiven to assume that this is new). But more to the point of this post, what is ontology?
In computer science, the classic definition is provided by Gruber. He defines ontology as a “specification of a conceptualization”. This definition although widely accepted some critics say it is too simplistic and incomplete. At the heart of this criticism is that Gruber’s definition reduces ontology to a model in people’s minds instead of a model that is representative of the universe that constitutes the domain.
I will try to explain what I think the critics say: in a nutshell, the argument being made is that ontology is much more than the concepts as understood by people in their own heads. Ontology needs to reflect completely the world of the domain being represented. To perhaps clarify this point of view, I imagined trying to see life through the eyes of an extremist (political or otherwise). To me, an extremist cannot possibly represent true reality of ‘what is’. Therefore, an attempt to reason about the world from that point of view would be doing the world injustice; since the vision of an extremist at best of times is not “true-to-the-world”.
My explanation may of course be a bit philosophical but as said before, ontology gets its roots from philosophy. Now, going back to Gruber. He does explicitly suggest that ontology pertains to modelling of knowledge of some domain be it is real or imagined. Further, he does insist that the modelling is as formal as specifying a program.
In conclusion, while the critics suggest that Gruber’s definition reduces an ontology to be seen as a mere “ad-hoc model built for some specific purpose”. I think I believe in Gruber’s definition for it is short and sweet (like me ) but also very open to interpretation. One possible intepretation is:
Ontology is a formal specification of conceptualization.