We take propositions to be nonlinguistic abstract objects that have
absolute truth values. From the perspective of situation theory,
this means that a proposition requires not only a type--that which
corresponds or doesn't correspond to the way things are--but also a
situation for the type to correspond to. Two basic
kinds of propositions are recognized in situation theory. An Austinian
proposition is determined by a situation and a type and is true if the
situation is of the type. A Russellian proposition is determined
by a type alone, and is true if some situation or other is of that
type. If we adopted the fourth thesis, that there is a total
situation, Russellian propositions could be taken as Austinian
propositions determined by this total situation.
Propositions are not infons. Infons characterize situations;
propositions are truth bearers. We shall assume that for each type of
situation and each situation there is an Austinian proposition that is
true just in case that situation is of that type. With respect
to Russellian propositions, we shall assume that for each type, there
is a proposition that is true just in case some situation is of that
type. This last is a strong assumption, that can lead to paradox. We
shall not concern ourselves with such issues in the present essay;
instead we urge all interested parties to consult the treatment in
Barwise and Etchemendy's The Liar.
Infons may have individuals and locations as constituents. When an infon with an individual or location as a constituent is the conditioning infon of a type, then we also say that the type has that individual or location as a constituent, as does the proposition determined by that type. A proposition whose type contains no such constituents, because each argument role has been quantified over, is general, in Kaplan's terminology; others are singular. We shall say that a singular proposition is about its constituents.