Uncorrected proofs -  John Benjamins Publishing Company JB[v.20020404] Prn:25/02/2005; 13:25 F: CI26508.tex / p.1 (46-107) Chapter 8 Principles and parameters in change* Elly van Gelderen Arizona State University . Introduction In this paper, I examine variation in use between pronouns and nouns, between differently case marked pronouns and nouns, and between the different per- sons. These differences do not constitute absolute tendencies, or splits, and they are only detectable when looking at large numbers of instances. I show how this variation has theoretical implications, in particular for Economy Principles, thus providing insights into I(nternalized)-language. I also consider historical data which show that fast change (e.g. the loss of morphological case) is sug- gestive of a parameter resetting, but that slow change (e.g. the noun pronoun split) is indicative not of a change in a principle but of a change in pronominal status. Using three corpora, I also raise some questions concerning the nature of linguistic data. . Background Some variationist work within generative grammar has revolved around invok- ing different parametric settings to account for different varieties (e.g. Henry 1995; Kayne 1989). I will look at nominal and pronominal variation in terms of a (Minimalist) Economy Principle that guides speakers to build the syntactic structure up to just a head rather than to a phrase. This predicts that personal pronouns are less often coordinated (since coordinates are phrasal) than nouns and this is borne out consistently in the corpora used. I call these differences ‘splits’, adapting a phrase from typology. Looking at these contrasts in a di- achronic corpus, there is very little change in 400 years, which is to be expected if we are dealing with an (invariable) principle. The changes that do occur are