Universally, human language changes over time. In that it is like a biological organism which keeps mutating and adapting itself to its environment, with some features rising in frequency and some declining. In the case of language, the origin of a change can be seen as a shift in the frequency of a given variant of linguistic expression (for instance, a given word order) in the speech of an individual. Why do such adaptations ever become necessary, that is, why do some features decline and other rise? And why do the adaptations take so long (often centuries), given that humans are extremely efficient learners? The goal of the CAUSALITY project is to investigate factors which push language change forward and those militating against it.
This investigation involves the retrieval of actual historical patterns of change from annotated databases, or treebanks, of Dutch, English, and Low German, as well as modeling, using Game Theory, the pragmatic reasoning the speakers engage in when evaluating their communicative choices. Modeling such reasoning is, by hypothesis, the key to uncovering causal relations between various grammatical changes. It is the communicative pressure that ensures that a decline of one feature (such as the informativeness of verbal endings) is "compensated" by an increase of an alternative feature (such as the frequency of pronominal subjects). By comparing the results of the game-theoretic simulations with the data retrieved from historical treebanks we can validate the communicative assumptions the models are based on. Finally, game-theoretic models will be incorporated into simulations involving multiple “generations” of artificial agents communicating with each other, to simulate a timeline and to pitch communicative efficiency against factors of group conservatism.
An important sub-project of CAUSALITY is creating a large treebank of historical Dutch. This will enable deeper insights into the evolution of Dutch and the way it gave rise to the modern dialectal landscape.
