ABSTRACT
In this chapter, we will introduce one of the most central subfields of metaphysics in the past century: ontology. Ontology is the study of what there is. In metaphysics, just as in science, one of the main things we want to find out is what kinds of things there are in the world.1 Although in the various sciences, discussion is usually confined to a particular domain of reality – biology may be concerned with what kinds of living things there are, physics with the subatomic constituents of matter – in metaphysics, we want to know what kinds of things there are in a sense that is even more general.
