Full Idea
Surveyed ontological systems show overlaps: properties and relations turn up in every system; individuals form part of five systems; abstracta, collections/sets and events are in four; facts are in two.
Gist of Idea
All systems have properties and relations, and most have individuals, abstracta, sets and events
Source
Jan Westerhoff (Ontological Categories [2005], §02)
Book Reference
Westerhoff,Jan: 'Ontological Categories' [OUP 2005], p.18
A Reaction
Westerhoff is a hero for doing such a useful survey. Of course, Quine challenges properties, and relations are commonly given a reductive analysis. Individuals can be challenged, and abstracta reduced. Sets are fictions. Events or facts? Etc.