Higgs bosons, mars missions, and unicorn delusions: How to deal with terms of dubious reference in scientific ontologies

Realist ontologies claim to represent what exists. Scientific discourse, however, often contains terms of dubious reference when describing current or past hypotheses, plans, or ideas. We present a framework in which a realist ontology is embedded in a description logics theory, the latter being indifferent regarding the existence of class members. It therefore may include units for various kinds of such terms. Using a taxonomy of terminological units we are able to distinguish between different kinds of classes in description logics theories based on whether the classes are believed to have instances or not. We also demonstrate how discourse using terms of dubious reference can be represented without departing from the principle of realist ontologies. An example OWL file can be downloaded from: http://purl.org/steschu/misc/ICB02011.