This paper argues that we use emotions to acquire our intuitive modal knowledge. In particular, it explores the role of surprise in knowledge of epistemic and circumstantial modal statements. It begins with a discussion of standard modal semantics which elucidates the sorts of epistemic problems that creatures like us face in their attempt to know modal statements. It then distinguishes various sorts of surprise and elucidates their fittingness conditions. After that, it formulates some surprise tests and exemplifies their scope and limits in modal knowledge acquisition. To initiate a surprise test, one supposes or imagines some proposition. Roughly, if that proposition gives rise to a surprise response, one judges it impossible; otherwise, one judges it possible.
Samuel Boardman (Mon,) studied this question.