The normative aspect of signalling and the distinction between performative and constative

The paper outlines an approach to the formal representation of signalling conventions, emphasising the prominent role played therein by a particular type of normative modality. It is then argued that, in terms of inferencing related to this modality, a solution can be given to the task J.L. Austin set but failed to resolve: finding a criterion for distinguishing between what Austin called constatives and performatives. The remainder of the paper indicates the importance of the normative modality in understanding a closely related issue: reasoning about trust in communication scenarios; this, in turn, facilitates a clear formal articulation of the role of a Trusted Third Party in trade communication.