Full Idea
There are countless predicates in English that have the appearance of sortal predicates but are purely generic (animal, machine, artefact), or are pure determinables for sortal determination (space-occupier, entity, substance).
Gist of Idea
Many predicates are purely generic, or pure determiners, rather than sortals
Source
David Wiggins (Sameness and Substance Renewed [2001], 2.6)
Book Reference
Wiggins,David: 'Sameness and Substance Renewed' [CUP 2001], p.69
A Reaction
This is preparing the ground for a specification of a sortal which defines something essential as being the hallmark of identity. It is never quite clear to me whether Wiggins's case rests on a nominal or a real essence.