Phasal diagnostics: A critical review

Phase theory posits that syntactic structures are not generated in a single step, but rather through multiple cyclic derivations. Relevant literature regards CP, vP, DP, PredP, and PP as phases. Conceptually, this theory assumes that language is divided into smaller processing units due to the limited capacity of working memory. Empirically, phases are regarded as interface segments that display independent distributions across the perceptual-motor and conceptual-intentional systems. The main criteria used to identify phases include agreement, uninterpretable features, case assignment, extraction, ellipsis, and wh-movement. Our study examined the applicability of these criteria to Turkish, finding that most are incompatible with its structural properties. Consequently, we suggest that the notion of phase should be approached more critically, and that more crosslinguistic data are needed to better evaluate the validity of the phase theory.

Keywords: Phase theory, Multiple spell-out, Agreement, Phasal diagnostics