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 non-referring terms when describing hypotheses, plans, or ideas. We present a framework in which a realist ontology is embedded in an description logics theory, which is indifferent regarding the existence of class members, and which may include representational units for representing various kinds of non-referring terms. Using a taxonomy of terminological units we are able to distinguish between different kinds of classes in the description logics theory and to identify classes as unsatisfiable, which are put as the extensions of non-referring terms. We also demonstrate how discourse using non-referring terms can be represented without departing from the principle of realist ontologies. An example OWL file can be downloaded from: http://purl.org/steschu/misc/ICBO2011.