Full Idea
Is it true that sets or universals cannot enter into causal interaction? Why can't we say that a set of things causes something, or something causes a set of effects? Or positive charge has characteristic effects? Or an event is a sort of set?
Gist of Idea
Abstracta can be causal: sets can be causes or effects; there can be universal effects; events may be sets
Source
David Lewis (On the Plurality of Worlds [1986], 1.7)
Book Reference
Lewis,David: 'On the Plurality of Worlds' [Blackwell 2001], p.83
A Reaction
This idea, and 8902, form a devastating critique of attempts to define abstraction in a purely negative way, as non-spatial and non-causal. Only a drastic revision of widely held views about sets, universals and events could save that account.
Related Idea
Idea 8902 If abstractions are non-spatial, then both sets and universals seem to have locations [Lewis]