Full Idea
Lewis proposes that a property is the set of its actual and possible instances.
Gist of Idea
A property is the set of its actual and possible instances
Source
report of David Lewis (On the Plurality of Worlds [1986], 1.5) by Alex Oliver - The Metaphysics of Properties 10
Book Reference
-: 'Mind' [-], p.22
A Reaction
I just can't make sense of any proposal that a property is a set. Things fall into natural sets because they have properties. Only a philosopher would believe such a weird proposal as this one. Triangular and trilateral?