The WAT-project will investigate the distribution and function of theme vowels (henceforth TVs)
in three Indo-European families (Romance, Germanic, and Slavic). TVs are
pieces of verbal morphology, typically consisting of a single vowel, that appear between the root
and the agreement endings. The overall aim of the WAT-project is to understand the nature of TVs, which raise both typological and functional questions. The typological questions concern the identification, classification, and distribution of TVs. There is no clear set of criteria defining TVs in the literature, suggesting that a unified definition may not be possible. Even the clearest instances of TVs turn out to have complex distributions on closer inspection. The WAT project will ask the following typological question: what are the dimensions along which the properties of TVs may vary, and what properties (if any) do all TVs have in common?
The functional question concerns the morphosyntactic function of TVs. In those cases where TVs correlate with semantic distinctions, they could be run-of-the-mill morphemes, i.e. minimal units of sound and meaning, which do not pose any special kind of analytical problem. But many TVs, like the ones in the Romance family, do not carry meaning, at least not in an obvious sense. Further, even where TVs do correlate with semantic distinctions they may not themselves be the actual carriers of these meanings. The question to be addressed here is the following: what is the function of TVs, given that in some cases they appear to be meaningless?
While TVs might seem like small and unimportant elements of language, their analysis is relevant to a number of broader questions. In particular, an analysis of TVs can provide insight into the question whether morphology is a separate module subject to its own laws, or whether it belongs to the same module as syntax. One of the main theoretical contributions of this project will therefore be to provide insight into the architecture of the grammar. In doing so, it will address Plato’s Problem: how do children acquire a fully productive faculty of language, which allows them to acquire TVs with complex properties, from finite input?