Single Idea 15732

[catalogued under 8. Modes of Existence / B. Properties / 11. Properties as Sets]

Full Idea

The usual objection to taking properties as sets is that different properties may happen to be coextensive. Creatures with hearts are creatures with kidneys. Talking donkeys are flying pigs (since there are none). Yet the properties differ.

Gist of Idea

Properties don't seem to be sets, because different properties can have the same set


David Lewis (On the Plurality of Worlds [1986], 1.5)

Book Reference

Lewis,David: 'On the Plurality of Worlds' [Blackwell 2001], p.51

A Reaction

This is the difficulty which Lewis proposes to solve by defining properties across possible situations as well as actual ones, so that the properties can come apart. Nice move.