The evolution of c-structure: prepositions and PPs from Indo-European to Romance

Within X-bar theory prepositions are standardly taken to constitute one of the core lexical categories along with verbs, nouns, and adjectives definable by the features [±V, ±N]. Synchronically, however they share properties with both lexical and functional categories, while diachronically they are usually the outcome of processes of grammaticalization affecting true lexical categories such as verbs, nouns, and adjectives. The present paper analyzes in detail the stages whereby prepositions in Latin and Romance evolve from earlier adverbial particles and concludes that this diachronic trajectory is best modeled within a framework that separates the relational structure of a PP from its configurational representation. It is argued that lexical-functional grammar, with its systematic distinction between f-structure and c-structure, provides a better account of these changes than conventional X-bar theory. In conclusion a possible role for optimality theory within a formal account of syntactic change is briefly sketched.