Reference Ontologies - Application Ontologies: Either/Or or Both/And?

The distinction between reference ontologies and application ontologies crept rather unobtrusively into the recent literature on knowledge engineering. A lot of the discourse surrounding this distinction – notably, the one framing the workshop generating this collection of papers – suggests the two types of ontologies are in some sort of opposition to one another. Thus, Borge et al. [3] characterize reference ontologies (more recently, foundational ontologies) as rich, axiomatic theories whose focus is to clarify the intended meanings of terms used in specific domains. Application ontologies, by contrast, provide a minimal terminological structure to fit the needs of a specific community. Reflecting their minimal nature, Masolo et al. [7] refer to such ontologies as “lightweight” ontologies. An application ontology can be lightweight in a second respect as well, namely, that it may not necessarily take the form of fully-fledged axiomatic theory. Rather, it might only be a taxonomy of the relevant domain, a division of the domain into a salient collection of classes, perhaps ordered by the subclass relation. Importantly, though, for an application ontology to “fit the needs of a specific community” needn’t require representational accuracy. In the “worst” case (from a reference ontology perspective), to fit the needs of a community is just to represent uncritically what people in that community think about the ontology’s domain. The preceding paragraph is perhaps a good first cut, but it strikes me that the distinction between reference ontologies and application ontologies has not been clearly made. To clarify the distinction and its significance is my goal in this short paper. I conclude that, in fact, the distinction is not really an opposition; rather, reference ontologies and application ontologies reflect different aspects of a single methodology for ontology development.