Ontologies and Knowledge Bases – Towards a Terminological Clarification


Guarino, N., & Giaretta, P. (1995). Ontologies and Knowledge Bases – Towards a Terminological Clarification. In Towards Very Large Knowledge Bases (pp. 25-32). IOS Press, Amsterdam, The Netherlands.

Goals of Research:

  • A terminological clarification about the term ontology based on the careful analysis of Gruber’s definition of ontology.


The paper is an attempt to clarify the term ontology and to analyze the widely accepted definition of ontology provided by Tom Gruber (ontology as an explicit specification of a conceptualization). It has been emphasized that there is a confusion between ontology as a conceptual framework at knowledge-level and a concrete artifact at symbol-level (p.1). The authors provide seven definitions of ontology used by different communities:

  1. Ontology as a philosophical discipline
  2. Ontology as a an informal conceptual system
  3. Ontology as a formal semantic account
  4. Ontology as a specification of a “conceptualization”
  5. Ontology as a representation of a conceptual system via a logical theory: A.characterized by specific formal properties; B.characterized only by its specific purposes
  6. Ontology as the vocabulary used by a logical theory
  7. Ontology as a (meta-level) specification of a logical theory

There are two interpretations of the ontologies as semantic entities (Def. 2-3), and syntactic objects (Def. 4-7) (P. 3). Formal ontology is defined as “the systematic, formal, axiomatic development of the logic of all forms and modes of being” (cited from Cocchiarlla, P.2), in this sense ontology would be a theory of distinction among two seperate sets of entities: among entities of the world; and among meta-level categories used to model the world (P.3). The term ontology is used as an artifact rather than a discipline in the knowledge engineering community. Authors proposes to use “conceptualization to denote a semantic structure [Def. 3], … and ontological theory to denote a logical theory intended to express ontological knowledge [Def. 5]”. They emphasize that the an “explicit” object in Gruber’s definition is a concrete symbol-level object. In addition, they distinguish among an intensional and extension notion of conceptualization (P. 3). Accordingly, a difference has been recognized between systems which are used to represent a state of affairs and a conceptualization which works more like a meta-language (P. 4). It is indicated that a particular theory is different from a specification of a conceptualization. The paper has been concluded with a proposal to confine the use of the term “ontology” to two senses: (1) a logical theory which gives an explicit, partial account of a conceptualization; (2) synonym of conceptualization as a semantic structure of intensional relationships (P. 5-7).

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