Single Idea 9667

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

Full Idea

I claim that mereological composition is unrestricted: any old class of things has a mereological sum. Whenever there are some things, even out of different possible worlds, there is something composed of just those things.

Gist of Idea

Mereological composition is unrestricted: any class of things has a mereological sum


David Lewis (On the Plurality of Worlds [1986], 4.3)

Book Reference

Lewis,David: 'On the Plurality of Worlds' [Blackwell 2001], p.211

A Reaction

To say the least, a rather unusual usage for the English word 'thing'. I presume that Lewis is in the grip of a slippery slope problem - that there is no way to define the borderline between things and non-things. Presumably 'class' is unrestricted too.