Research into comparative syntax over the last four decades has revealed that, despite some quite considerable superficial differences, syntactic variation among different languages and varieties is not random, but is ultimately constrained by a small and finite set of principles and parameters, the number and nature of which can be successfully teased apart especially through the careful study of closely related languages and varieties where, all other things being equal, a particular parametric choice can be readily isolated. It is for this reason that investigations of parametric variation in the area of syntax have so often drawn on Romance data since empirical investigations of Romance morphosyntax, especially of non-standard varieties and dialects in more recent times, have uncovered a wealth of small-scale microvariation. Drawing on such examples as the variation found in subject clitic systems, auxiliary selection (variously driven by transitivity, mood, tense, and grammatical person), active participle agreement, the extent and distribution of verb movement, sentential negation, and C(omplementizer)-systems (e.g., dual/triple complementizer systems; V2; availability of V-to-C movement and focus fronting), this chapter provides a critical overview of the some of the principal dimensions of morphosyntactic parametric variation with the aim of identifying the nature of the choices involved and, in particular, the differences between macro-, meso-, micro-, and nanoparameters and how these are formally organized within the grammar, the interaction between these parameters both in diachrony and synchrony, and what the formal limits of such parametric variation are.

In this chapter the editors introduce the book and its aim of showing how the study of comparative and historical data from the Romance languages can illuminate general linguistics. After a brief presentation of the volume and its structure, the editors reflect on how their personal experiences of working with data from the Romance languages have led them to reflect on wider issues in general ling uistics. Recurrent themes in their work have been, respectively, morphosyntactic change (Ledgeway) and sound change and its morphological consequences (Maiden). Among the topics whose theoretical implications are explored are: parametric variation, universals, typological variation, pro-drop, word order, linguistic theory and philology, complementizer systems, the interaction of phonological and morphological factors in morphologization, the problem of defining a language family, and the perils of ‘standard language bias’ in the practice of historical linguistics. While these may appear a quite heterogeneous set of issues, they are treated in a way that prompts some major shared fundamental conclusions, in particular that Romance linguistics can make its most powerful contributions to general linguistics when Romance linguists exploit to the maximum the extraordinary wealth of historical and comparative data which the Romance languages and dialects offer them.