Elements of a Plan - Based Theory of Speech Acts * PHILIP

This paper explores the truism that people think about what they say. It proposes hat, to satisfy their own goals, people often plan their speech acts to affect their listenerr’ beliefs, goals, and emotional states. Such language use mn be modelled by viewing speech acts as operators in a planning system, thus allowing both physical and speech acts to be integrated into plans. Methodological issues of h o w speech acts should be defined in a planb a d theory are illustrated by defining operators for requesting and informing. Plans containing those operators are presented and comparisons are drawn with Searle’s formulation. T h e operators are shown to be inadequate since jhey cannot be composed to form questions (requests to inform) and multiparty requests (requests to request). By redining the operator definitions and by identifying some of the side efFects of requesting, compositional adequacy is achieved. The solution leads to a metatheoretical principle for modelling speech acts as planning operators.