Abstract

In this paper we are focused on the relation between an Ontology (with the capital "O") qua philosophical discipline and an ontology (with the lowercase "o") qua branch of Computer Science. In our view "Ontology" refers to all philosophical groups or schools which take some position on the reality. The meaning of 'ontology' in the second case is not that easy to grasp because of the variety of artefacts which are called 'ontologies' and many activities - aiming at creating the ontologies - called ontological engineering . In general we could state that an ontology is something what is called "ontology" beyond Philosophy, mostly in the Knowledge Management, Artificial Intelligence, Conceptual Modelling or Ontological Engineering and what refers to an engineering artefact describing certain aspect of reality. So understood ontology is always tied to certain language (preferably a logical one) or more precisely to the set of the sentences of this language. It is said that these sentences constitute an ontology and specify the intended meaning of the terms used in these sentences. The ontologists usually focus on describing their conceptualization of the relevant for them aspects of reality. In their ontologies only these properties of reality are taken into account, which are considered as important for the sake of the application. In this sense ontological engineering may ignore Ontologically essential properties, i.e. the ones important from the purely philosophical perspective. The simplest ontologies are catalogues - the list of terms or numbers denoting certain object, glossaries - containing additionally the definitions of the terms, thesauri - the glossaries in which the hierarchy of the terms appear and taxonomies - in which the primitives are hierarchically structured in order to enabling the properties' inheritance. The most sophisticated ontologies are called formal ontologies and they are logical theories fully axiomatized. Ontologies are also divided on the top-level ontologies concerning very general and mostly abstract entities (e.g. property, agent, time) and the domain ontologies dealing with some small domains (e.g. car's parts). For a better understanding of the wide variety of ontologies we give an example of three ontologies: WordNet (thesaurus-like ontology), Cyc (top-level, formal ontology) and Enterprise Ontology (domain ontology). The Ontology plays an important role in ontological engineering. We notice that the ontological engineers more and more often rely on the philosophical literature looking for the solutions of the ontological problems. It is especially visible in the top-ontologies where many Ontological distinctions have been directly adopted. On the other hand we must sadly stress that philosophers seem to be not interested in the ontological engineering at all. We'd like to introduce ontology to t