Reasoning about assertions, obligations and causality on a categorical semantics for a logic for pragmatics

Abstract

The aim of the logic for pragmatics considered in this work is to provide a logical framework that formalises reasoning about the pragmatic forces with which a sentence may be uttered. The concept of pragmatic or illocutionary force comes from speech act theory and plays a crucial role also in certain branches of artificial intelligence, in particular in the development of communication protocols for software agents. Instead of considering the full-blown theory of speech acts, we focus on speech acts that either have the pragmatic force of an assertion or the pragmatic force of an obligation, and on how these speech acts may be related to each other. In particular, we are interested in a principle proposed by Bellin and Dalla Pozza that allows one to promote acts of obligations through causal chains of acts of assertions. The main achievement of this thesis is a sound and complete categorical semantics for a logic for pragmatics incorporating the aforementioned principle. One of the benefits of the proposed semantics is that it allows one to deal with conditional obligations as well, thus extending the framework in a very interesting way. Although the logical framework considered in this work incorporates only two types of speech acts, we hope to be able to show that we have a well-behaved core fragment that can serve as a fruitful basis for further investigations.