 Second, various topics in metaphysics have evolved historically around linguistic facts, generally used as manifestations of shared intuitions or of reality itself  (§1.2).  By making full use of empirical and theoretical research in linguistics, natural language ontology can shed a significant light on those topics. For example, linguistic facts have played an important role in the debate surrounding universals since the middle ages, where questions were pursued such as whether wisdom is a term that picks out an abstract universal or just its various instances. Natural language examples play a significant role also in contemporary discussions of abstract objects (Zalta 1983; Boolos 1998), properties (Chierchia &amp; Turner 1988; Bealer 1993), and types (Wetzel 2009). Those discussions generally presuppose the view that natural language allows reference to a wide range of abstract objects, though that view has been challenged on the basis of other linguistic generalizations and analyses  (§4.1).  