A Game-Theoretic Analysis on the Use of Indirect Speech Acts

In this paper we will discuss why in some circumstances people express their intentions indirectly: the use of Indirect Speech Acts (ISA). Based in Parikh’s game of part information and Franke’s IBR model, we develop a game-theoretic model of ISA, which is divided into two categories, namely non-conventional ISA and conventional ISA. We assume that non-conventional ISA involves two types of communication situations: communication under certain cooperation and that under uncertain cooperation. We will analyze the cases of ironical request and implicit bribery as typical instances of non-conventional ISA of each situation type, respectively. We then apply our model to analyze the use of conventional ISA from an evolutionary perspective, which is inspired by Lewisian convention theory. Our model yields following predictions: the use of non-conventional ISA under certain cooperation relies on the sympathy between interlocutors, which blocks its evolution towards conventional ISA; in uncertain cooperation situations, people are more likely to use ISA, which helps its conventionalization.