thatness
Thatness, often discussed in philosophy under the closer term haecceity, refers to the individuating aspect of a thing that makes it this particular object rather than any other. It is the “thisness” or “thatness” that differentiates one entity from another when their qualitative properties might otherwise appear indistinguishable. In this sense, whatness or quiddity describes the general nature or essence of a kind, while thatness designates the particular instance of a thing.
Etymology and origin: the term haecceity derives from Latin haecceitas, from haec meaning “this.” It was developed
Philosophical role and debates: thatness is often treated as an individuating primitive or non-qualitative property—one that
Relation to other concepts: related terms include thisness, this-ness, and quiddity (whatness). While quiddity concerns the