On the origin of the Germanic strong verb system

This paper proposes a solution for two characteristic peculiarities of Germanic, the unique systematisation and functionalisation of verbal ablaut on the one hand, and the drastic reduction of verbal categories compared to what is commonly assumed for the parent language on the other. Both phenomena are well known and described in the relevant textbooks, in which they have mostly been ascribed to some kind of internal development left largely unspecified. Despite the fact that this null hypothesis seems to have a privileged position in historical linguistics, it cannot be considered an explanation. By contrast, it is suggested in this paper that these two phenomena, namely the systematisation and functionalisation of two qualitative ablaut grades in the Germanic strong verb and the reduction of the inherited Proto-Indo-European tense system, are interrelated and that these innovative developments can be attributed to language contact: Speakers of a superstratum language with a highly systematised verbal ablaut recognised a similar feature in Pre-Germanic when they had to learn the language of the people they dominated. In this process of language shift the learners over-generalised ablaut as the subjectively most salient morphological feature and subsequently transferred the native semantic content onto the familiar structure. Due to the linguistic compatibility and the high social prestige of the former superstratum speaker's sociolect this structural change survived and eventually became a property of Proto-Germanic. This hypothesis is supported by research on language contact, bilingualism and language acquisition.