Vagueness and Decision
If linguistic vagueness is more fundamental than propositional vagueness, it is natural to think that vague propositions won’t play a substantive role in decision theory. On a linguistic picture, what it is rational for an agent to do is completely determined by their attitudes towards precise propositions. This is vacuously true if all propositions are precise, but it also seems like a natural idea if, like the expressivist discussed in Chapter 8, a distinction is drawn between metaphysically ‘first-rate’ precise propositions and metaphysically ‘second-rate’ vague propositions. This chapter considers how to formulate decision theory in a setting where there are vague propositions, and discusses ways in which vague beliefs, desires, and actions can have concrete impacts on practical deliberation and action.