Meta-ontology concerns itself with the nature and methodology of ontology, with the interpretation and significance of ontological questions such as those exhibited above. The problem of ontological commitment is a problem in meta-ontology rather than ontology  proper.[1]  The meta-ontologist asks (among other things): What entities or kinds of entity exist according to a given theory or discourse, and thus are among its ontological commitments? Having a criterion of ontological commitment for theories is needed, arguably, if one is to systematically and rigorously attack the problem of ontology: typically, we accept entities into our ontology via accepting theories that are ontologically committed to those entities. A criterion of ontological commitment, then, is a pre-requisite for ontological inquiry.