Abstract

I show that the act-type theories of Soames and Hanks entail that every sentence with alternative analyses (including every atomic sentence with a polyadic predicate) is ambiguous, many of them massively so. I assume that act types directed toward distinct objects are themselves distinct, plus some standard semantic axioms, and infer that act-type theorists are committed to saying that ‘Mary loves John’ expresses both the act type of predicating [loving John] of Mary and that of predicating [being loved by Mary] of John. Since the two properties are distinct, so are the act types. Hence, the sentence expresses two propositions. I also discuss a non-standard “pluralist” act-type theory, as well as some retreat positions, which all come with considerable problems. Finally, I extrapolate to a general constraint on theories of structured propositions, and find that Jeffrey King’s theory has the same unacceptable consequence as the act-type theory.