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)

According to Grice's `Cooperative Principle', human communicators are involved in a cooperative endeavor. The speaker attempts to make herself understood and the listener, in turn, assumes that the speaker is trying to maximize the ease and effectiveness of communication. While pragmatists recognize that people do not always behave in such a way, the Cooperative Principle is generally assumed to hold. However, it is often the case that the interests of speakers and listeners diverge, at least to some degree. Communication can (...) arise in such situations when the cost of signaling is high enough that it aligns the interests of speaker and listener, but what happens when the cost of signaling is not sufficient to align the interests of those communicating? In these cases the theoretical prediction is that they will reach a partially informative system of communication. Using methods from experimental economics, we test whether theoretical predictions are borne out. We find that subjects do learn to communicate without the cooperative principle. (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. (shrink)