Full Idea
Lewis suggests that we take attitudes to have properties, rather than propositions, as contents. To stand in the belief relation to a property is to self-ascribe that property.
Gist of Idea
Attitudes involve properties (not propositions), and belief is self-ascribing the properties
Source
report of David Lewis (Attitudes De Dicto and De Se [1979]) by Robert C. Solomon - Erotic Love as a Moral Virtue 05.1
Book Reference
Cappelen,H/Dever,J: 'The Inessential Indexical' [OUP 2013], p.90
A Reaction
This is the sort of convoluted suggestion that Lewis has to come up with, in pursuit of his project of a wholly consistent metaphysics. Examine Lewis's account of properties before you judge this proposal! Self-ascribing is joining a set!