Ontology and Ideology
Let T be any theory. If you worry about T's overabundant ontology, there is a simple way to translate it into a theory T_i with a very sparse ontology: For every sentence S in T introduce a new primitive predicate P that applies to a world w iff S is true at w. Then replace S by 'the world is P'. A more elegant method would not introduce a new primitive predicate for every sentence, but rather use structured predicates, that are systematically built up in the way the sentence is built up. (See Quine, 'Variables explained away', and Prior, 'Egocentric Logic'). T_i is a theory that says the same as T with an ontology of just one individual - the world. The price to pay for this reduction in ontology is an overabundant ideology: Who wants all these weird predicates? Nobody.
Conversely, if you worry about T's overabundant ideology, there is a simple way to translate it into a theory T_o with a very sparse ideology: For every sentence S in T introduce a primitive constant c and declare that c exists at a world w iff S is true at w. Then replace S by 'c exists'. Again, it would be more elegant to use structured terms instead of primitive constants. We may have to introduce another bit of ideology, some functor to to bind the term's consituents together. T_o says the same as T with an ideology of just one quantifier -- existence -- and maybe also a primitive functor -- 'unmereological composition', say. This time the price to pay for the reduction in ideology is an overabundant ontology: Who wants all these weird things? Armstrong. He calls them states of affairs.