What learning Latin verbal morphology tells us about morphological theory

The Classical Latin verb has featured prominently in theoretical morphology. In particular, the notoriously unpredictable forms of the past participles that nevertheless show reliable syncretism with a semantically diverse set of deverbals challenge our notions about the relationship between form and meaning. The various treatments of this system disagree not only in their theoretical building blocks but also in their basic assumptions about what ought to be explained, which makes it difficult to properly evaluate them against one another. This paper aims to empirically motivate the prior assumptions about productivity and arbitrariness that drive these accounts. In applying insights developed for child language acquisition to a large Latin corpus, the theoretical frameworks are compared on equal footing. It becomes clear that the productive past participle forms do not line up well with the frequency-based assumptions of prior accounts and instead mirror the diachronic developments that the system underwent on its path to Romance. A new treatment is proposed to incorporate the acquisition results and to conform with diachronic outcomes. The methods developed here reveal explanatory gaps in the theories that had not previously been appreciated and emphasize the importance of quantitative evidence from a range of sources in future morphological analysis.