Single Idea 13268

[catalogued under 9. Objects / C. Structure of Objects / 8. Parts of Objects / c. Wholes from parts]

Full Idea

Lewis says that if not every class has a fusion then there must be a restriction on composition. The only plausible restrictions would be vague ones, which is impossible, because then whether composition occurs would be vague. So every class has a fusion.

Gist of Idea

There are no restrictions on composition, because they would be vague, and composition can't be vague


report of David Lewis (On the Plurality of Worlds [1986], p.212-3) by Theodore Sider - Four Dimensionalism 9.1

Book Reference

Sider,Theodore: 'Four Dimensionalism' [OUP 2003], p.121

A Reaction

This is Lewis's key argument in favour of unrestricted composition, his Vagueness Argument. Why can't composition be vague? If you gradually reassemble a broken mirror, at what point does the mirror acquire its unity?