Giuseppe Spolaore & Matteo Plebani


Existence-entailing subject matters


We ordinarily use the notion of subject matter in a variety of circumstances: books belong to the same section of the library when they are about the same topic, emails have a subject line, we criticize those who change the subject. However, one might wonder just what subject matter are. As David Lewis pointed out, sometimes it is natural to identify a subject matter with a part of a world: the XVII century, for Lewis, is part of our world and two worlds are identical with respect to the XVII century iff the XVII century of one world is a perfect duplicate of the XVII century of the other (Lewis 1988b). However, some subject matters cannot be easily identified with parts of the world: as Lewis notices, two worlds might be identical with respect to the SM *the number of stars* even though no part of one world is an exact duplicate of any part of the other. Rather than thinking of *the number of stars* as a part of the world, we can think of it as a partition of the set of possible worlds, where two worlds are in the same cell if there as many stars in one as in the other. In this talk, we start from the distinction between part-based and non-part based subject matters (Humberstone 2000) and introduce a further distinction between existence-entailing and non-existence-entailing subject matters. We argue that all existence-entailing subject matters are part based, but the converse fails.

Date / Time / Place

June 23rd / 9:35 / Aula 0A