According to the Maxim of Quality, rational agents tend to speak honestly. Due to the influence of Grice, a connection between linguistic rationality and honesty is often taken for granted. However, the connection is not obvious: structural rationality in language use does not require honesty, any more than it requires dishonesty. In particular, Quality does not follow from the Cooperative Principle and structural rationality. But then what is honest rational speech? I propose to move the discussion in the context of (...) Stalnaker's theory of assertion. From this perspective, although there is no most rational way to behave, Quality follows from the structure of Stalnakerian conversations if interlocutors are sensitive to credibility. In this case, honesty is built on the expectation of reciprocity, and cooperativity is an outcome and not a precondition of rational communication. A benefit of my discussion is that the account of linguistic rationality falls under the more general view of interactive rationality familiar from theoretical economics. (shrink)

Communication involves a great deal of uncertainty. Prima facie, it is therefore surprising that biological communication systems—from cellular to human—exhibit a high degree of ambiguity and often leave its resolution to contextual cues. This puzzle deepens once we consider that contextual information may diverge between individuals. In the following we lay out a model of ambiguous communication in iterated interactions between subjectively rational agents lacking a common contextual prior. We argue ambiguity’s justification to lie in endowing interlocutors with means to (...) flexibly adapt language use to each other and the context of their interaction to serve their communicative preferences. Linguistic alignment is shown to play an important role in this process; it foments convergence of contextual expectations and thereby leads to agreeing use and interpretation of ambiguous messages. We conclude that ambiguity is ecologically rational when interlocutors’ contextual expectations are generally in line or they interact multiple times in an informative context, enabling for the alignment of their expectations. In light of these results meaning multiplicity can be understood as an opportunistic outcome enabled and shaped by linguistic adaptation and contextual information. 1Meaning Multiplicity in Communication 2Ambiguous Signalling through Pragmatic Inference 2.1Preliminaries 2.2Signalling behaviour 2.3Communicative success 2.4Iterated interactions 3Predictions for Single and Iterated Interactions 3.1Simulations 3.2Exploration and past experience 3.3Preemptive adaptation 4Discussion 5Conclusion Appendix. (shrink)

This paper analyzes communication with a language that is vague in the sense that identical messages do not always result in identical interpretations. It is shown that strategic agents frequently add to this vagueness by being intentionally vague, i.e. they deliberately choose less precise messages than they have to among the ones available to them in equilibrium. Having to communicate with a vague language can be welfare enhancing because it mitigates conflict. In equilibria that satisfy a dynamic stability condition intentional (...) vagueness increases with the degree of conflict between sender and receiver. (shrink)