Now That You Mention It - Awareness Dynamics in Discourse and Decisions

We model unawareness of possibilities in decision-making and (linguistic) pragmatic reasoning. A background model is filtered through a state of limited awareness to provide the epistemic state of an agent who is not attending to all possibilities. We extend the standard notion of awareness with assumptions (implicit beliefs about propositions the agent is unaware of) and define a dynamic update for ‘becoming aware.’ We give a propositional model and a decision-theoretic model, and suggest that decision problems should in general be seen as filtered models in this sense, describing only those features of the situation which the modeller considers relevant and the agent is aware of. We show how pragmatic relevance reasoning can be described in this framework, extending a standard definition to the case of awareness updates. An utterance can be relevant even if semantically uninformative, if it brings relevant alternatives to awareness. This gives an explanation for the use of possibility modals and questions as hedged suggestions, bringing possibilities to awareness but only implicating their degree of desirability or probability. ∗The authors are listed in alphabetical order.