The importance of interlinguistic similarity and stable bilingualism when two languages compete

One approach for analyzing the dynamics of two languages in competition is to fit historical data for the number of speakers of each with a mathematical model in which the parameters are interpreted as the similarity between those languages and their relative status. Within this approach, on the basis of a detailed analysis and extensive calculations, we show the outcomes that can emerge for given values of these parameters. In contrast to previous results, it is possible that in the long term both languages may coexist and survive. This happens only where there is a stable bilingual group, and this is possible only if the competing languages are sufficiently similar, in which case its occurrence is favoured by both similarity and status symmetry.