The emergence of differential case marking
This paper shows that grammatical argument marking need not be inherent to language but can result from language use. For this, a computer model is used that simulates the emergence of differential case marking in artificial protolanguages in which only lexical expressions and very general communicative principles are used. Agents check the expected success of their utterances and initially add lexical ad hoc markers to make the distributions of roles clear if deemed necessary. Such role markers need not be very specific, as they only have to distinguish between maximally two, often very different, predicate roles. Over time, as popular marking solutions become less costly to produce and irrelevant meaning dimensions are removed from their lexical representations, case markers may develop. It is also shown how this development can be impaired if alternative strategies, such as Agent First, are used.