The role of bilinguals in language competition

International audienceWe study the role played by bilinguals in competition between two languages and in bilingual community formation. To this aim we introduce a simple three-state model that combines the Minett-Wang model, in which bilinguals do not directly affect the probability of an individual's transition from monolingualism to bilingualism, and the Baggs-Freedman model, where perhaps only bilinguals can trigger this transition. The model used predicts the possibility of the existence of a stable bilingual community without any particular conditions being assumed for the two competing languages: the asymptotic stability of the bilinguals' community is due only to the type of dynamics regulating the transitions between different linguistic groups. The proposed model and the obtained results give some suggestions for the conditions necessary for the formation of a stable bilingual community. First, it is important that the bilinguals are valid representatives of the two languages, in the sense that they are regarded by monolinguals also as speakers of the other language. Moreover, the transition from bilinguals to monolinguals must be smaller than the reverse transition. Unless both these conditions are met, the stable equilibrium solution to the language competition is a monolingual society