If a semantic theory is restricted to sentence types rather than propositions, it lacks the resources to correctly capture the meaning of propositional attitude reports.

A natural analysis of such sentences is that they express a relation between Seneca or Columbus and the propositions that man is a rational animal or that the world is round, where such propositions are objective abstract entities that are the ultimate vehicles of truth and meaning. But there has been—and no doubt always will be—skepticism about the existence of such entities and this has motivated the view that sentences such as (1) and (2) express relations between agents and sentence types or