Parameters, patterns, and the reality of UG C. Guardiano^, G. Longobardi°, A. Ceolin°, G. Silvestri°*, L. Bortolussi°, A. Sgarro° ^Università di Modena e Reggio Emilia, °Università di Trieste, *Università di Pisa Keywords: Principles&Parameters; Parametric Comparison; Syntactic Patterns. Goals: arguing that parameters of UG 1) really exist; 2) are possibly ‘more’ real than sets of ‘syntactic patterns’, as used by surface-oriented and non-formal approaches to linguistic variation and grammatical descriptions (e.g. Dixon’s 1997 Basic Linguistic Theory). Background: in many respects, Principles&Parameters models of UG are a conceptually plausible answer to the problem of explanatory adequacy (Chomsky 1964), i.e. ultimately to the failures of inductive and empiricist models of language acquisition pointed out by the biolinguistic program (most explicitly since Chomsky 1959 or Lenneberg 1964); however, empirically, parametric theories are not yet sufficiently corroborated, since nobody has so far indisputably assessed the effectiveness of such nativist approaches to the acquisition of grammatical diversity by implementing a parameter setting system over a large and realistic collection of parameters (Fodor 2001, Yang 2003; cf. Chomsky 1995, 7: “The P&P model is in part a bold speculation rather than a specific hypothesis. Nevertheless, its basic assumptions seem reasonable…. and they do suggest a natural way to resolve the tension between descriptive and explanatory adequacy”). It is therefore debatable that a P&P model has actually attained substantial explanatory adequacy, though progressing beyond language- specific descriptive adequacy. Indeed, many statements in the parametric literature are of an existential form and attain crosslinguistic descriptive adequacy, though just ‘locally’ (e.g. ...there is a parameter so-and-so neatly distinguishing some sets of properties in such-and- such languages). To address the need for more solid arguments in favor of P&P, Longobardi (2003) suggested the opportunity 1) of adopting a Modularized Global Parametrization strategy, aiming at studying together relatively many (and closely interacting) parameters in relatively many languages within the circumscribed domain of some small modules of grammar; 2) of beginning to aim at further testing grounds and levels of success, beyond classical explanatory adequacy: in particular to aim at satisfactory accounts of the actual distribution of grammatical diversity in time and space (termed ‘historical adequacy’). Methods: elaborating on previous work (e.g. Longobardi and Guardiano 2009), a sample of more than 50 carefully identified binary parameters in three submodules of DP syntax, set in over thirty languages, is focused on; this sample is complemented with a set of hypotheses about UG constraints, defining two levels of deductive structure: one determines the traditional covariation of properties following from the same parameter, the other encodes an extraordinarily rich implicational hierarchy among parameters themselves (much more pervasive and detailed than originally hinted in Baker 2001). Phylogenetic programs of biostatistical derivation have been applied to this database to formally measure syntactic diversity and generate hypotheses of phylogenetic trees and networks. Specific mathematical procedures (a non-trivial sampling algorithm capable of dealing correctly with the universal constraints imposed on parameter setting) have now been elaborated on purpose, to compute the width of potential diversity allowed by this fragment of UG and to compare it to the one observed in the actual language set. First results: through so designed formal methods, it can be shown that the distribution of actual syntactic distances provided by the parametric system is statistically highly significant (non-accidental and requiring historical explanation). The results (distances, trees, and 1