 There are various ways in which philosophers have used natural language to clarify metaphysical intuitions. One of the most common ways in which philosophers draw on language concerns the denotations of particular types of referential noun phrases (NPs). It is a standard assumption in both philosophy and linguistics that referential NPs stand for entities and predicates express properties of entities. The types of predicates acceptable with a particular type of referential NP are thus indicative of the ontological category of the entities that that type of NP denotes. The types of NPs philosophers make use of include bare adjective nominalizations like wisdom when arguing for qualities or properties, deverbal nominalizations like laughter when arguing for events, modified adjective nominalizations like Socrates’ wisdom when arguing for tropes or particularized properties (see entry on  tropes),  NPs with a relational use of number such as the number of planets when arguing for numbers as objects, and fact-referring terms like the fact that it is raining or the facts when discussing the nature and role of facts (Austin 1950; Strawson 1950). Other ways in which natural language appears to reflect ontology and which have played a role in philosophy will be discussed later  (§2.2).