Planning Perlocutionary Acts

We suggest a model of perlocutionary acts in order to explain how an actor plans speech acts to ob tain a response from a partner. We introduce two knowledge structures, namely games and contracts, which are used together with themes by the mental processes underlying perlocutionary acts. We present our model through the discussion of a paradigmatic example; in particular we focus on the problem of shifting from the wants of the actor to the wants of the partner. Our analysis is developed at different levels of detail through the identification of CAUSE-TO-WANT, CONVINCE and REQUEST actions. Eventually , we discuss some theoretica] implications of our approach to perlocution. I THEORETICAL FRAMEWORK Recent AI research in the field of communication shows interest for speech act theory and its basic concepts of illocution and perlocution, as developed by Searle (1969). Cohen and Perrault (1979) and Per_ rault and Allen (1980) propose a forma] model of il locutionary acts, both direct and indirect. Such a model has been introduced for the implementation of an artificial system which participates in a natural language conversation. Given such a target, the treatment of perlocutionary acts is simplified. On the contrary, a deeper analysis of perlocutionary acts is a fundamental component for a theory of human communication which accounts for the response of interacting subjects. Starting from the results achieved by Allen, Coh en and Perrault, we suggest a model of perlocutiona ry acts in order to explain how an actor plans speech acts to obtain a specific response from a partner. To explain the usual felicitous outcome of communication, we assume that the actor is able to handle a model of the partner. This assumption is consistent with the general hypothesis that the actor and the partner share the same pragmatic competence. II CAUSING TO WANT Let us assume that an actor A has a goal and forms a plan to achieve it. If the plan is interper_ sonal, i.e. it involves the cooperation of a partner P, A has to induce P to perform his role. In particular , we are interested in the most standard way of achieving such a result, namely communication. Following Cohen and Perrault (1979), we assume that:-A performs an illocutionary act, the effect of which is P's recognition of A's want that P performs a specific action TT;-a process called CAUSE-TO-WANT is triggered by the illocutionary effect and generates …