Full Idea
Frege's notion of an object plays two roles in his semantics. Objects are the referents of proper names, and they are equally what predicates are true and false of.
Gist of Idea
Frege's 'objects' are both the referents of proper names, and what predicates are true or false of
Source
report of Gottlob Frege (On Concept and Object [1892]) by Michael Dummett - Frege Philosophy of Language (2nd ed) Ch.4
Book Reference
Dummett,Michael: 'Frege Philosophy of Language' [Duckworth 1981], p.474
A Reaction
Frege is the source of a desperate desire to turn everything into an object (see Idea 8858!), and he has the irritating authority of the man who invented quantificational logic. Nothing but trouble, that man.
Related Idea
Idea 8858 Philosophers keep finding unexpected objects, like models, worlds, functions, numbers, events, sets, properties [Yablo]