Full Idea
Wiggins bases sortal essentialism on the notion that a thing's principle of individuation is essential to it.
Gist of Idea
Wiggins's sortal essentialism rests on a thing's principle of individuation
Source
report of David Wiggins (Sameness and Substance Renewed [2001]) by Penelope Mackie - How Things Might Have Been 7.1
Book Reference
Mackie,Penelope: 'How Things Might Have Been' [OUP 2006], p.119
A Reaction
My problem with this is that individuation is a human activity, not an intrinsic feature of the entities in the external world. Entities presumably have a 'unity', but I'm not sure about a 'principle' that does that job, though Aristotle is sympathetic.
Related Idea
Idea 15834 Brody bases sortal essentialism on properties required throughout something's existence [Brody, by Mackie,P]