 One of them concerns natural language ontology itself, when its subject matter is an ontology that may diverge from the ontology of what is considered real. How is natural language ontology compatible with what is widely regarded as a fundamental requirement on semantic theory, namely that of giving truth conditions? For a sentence S about an entity d to be true or false, what makes S true or false, it seems, needs to be a part of reality that includes d itself, and thus d needs to be a real entity, rather than part of an ontology of “appearances”. There are various options to pursue, each of which may be adopted for just some part of the ontology reflected in natural language. One option is that natural language displays ontological notions or items that simply fail to be real, and thus speakers making use of them in their utterances are in error. Second, entities in the ontology of natural language may have the status of fictional entities, which means that a sentence about such entities may not be able to be “really” be true (unless it predicates a property of the fictional entity as a fictional entity, with predicates such as is a fictional character) (see entry on  nonexistent objects, section nuclear and extranuclear properties).  Third, entities in the ontology of natural language, even if not considered fundamental, may be considered derivative, yet real, which would allow sentences involving reference to them to be true. As was mentioned in  Section 1.1,  some proponents of natural language ontology remain agnostic regarding the metaphysical status of the items that natural language ontology posits, as long as they are motivated by empirical generalizations and theoretical linguistic considerations.