An
ontological commitment refers to a relation between a language and certain objects postulated to be extant by that language. The 'existence' referred to need not be 'real', but exist only in a
universe of discourse. As an example, legal systems use vocabulary referring to 'legal persons' that are collective entities that have rights. One says the legal doctrine has an
ontological commitment to non-singular individuals. In
information systems and
artificial intelligence, where an
ontology refers to a specific vocabulary and a set of explicit assumptions about the meaning and usage of these words, then an ontological commitment is an agreement to use the shared vocabulary in a coherent and consistent manner within a specific context. In philosophy a "theory is
ontologically committed to an object only if that object occurs in
all the ontologies of that theory"