Full Idea
Essentialism is a reasoning heuristic that allows us to make fairly good predictions much of the time, but it should not be confused with the structure of reality.
Gist of Idea
Essentialism is useful for predictions, but it is not the actual structure of reality
Source
Susan A. Gelman (The Essential Child [2003], 11 'Discussion')
Book Reference
Gelman,Susan A.: 'The Essential Child' [OUP 2005], p.324
A Reaction
She particularly cites biology as the area where it might be inaccurate. I'm beginning to think that the operations of induction are the place to look for an good understanding of essentialism.