Full Idea
Essentialism is concerned with the nature of a group, whatever the category it falls under.
Gist of Idea
Essentialism concerns the nature of a group, not its category
Source
Michael Devitt (Resurrecting Biological Essentialism [2008], 6)
Book Reference
Devitt,Michael: 'Putting Metaphysics First' [OUP 2010], p.228
A Reaction
This seems to me such a simple and obvious point that I am amazed that anyone rejects it, yet lots of people seem to think that an essence is just some sort of category.