This article discusses three concerns regarding Becker and Gouskova’s (2016) analysis of Russian yers that relies on cluster-based yer vocalization and two sublexicons (morphemes with and without yers), to which lexically specific constraints refer. First, it misses the basic generalization about Slavic yers expressed by the established analysis (Lower): yer vocalization is triggered by five different mechanisms, instead of one mechanism under Lower. It is further shown that the major objection against Lower disappears when the existence of final empty nuclei is recognized. Second, Becker and Gouskova confound generalizations about the lexical distribution of yers in morphemes and the computational mechanism that decides which yers appear on the surface. They argue that Lower was established before relevant cluster-based generalizations were discovered, hence misses out on relevant empirical material that invalidates its central idea, that clusters are irrelevant for yer vocalization. However, the phenomena their argument is based on do not concern yer vocalization (computation): they are lexical in kind and therefore confirm the irrelevance of clusters for yer vocalization, supporting Lower. Third, although generalizations about yer-deletion-created clusters are central for Becker and Gouskova’s analysis, they are irrelevant for learners (children or adults). The authors’ experimental evidence precisely shows that speakers are happy to lexicalize and compute sequences (such as yerCC) that are absent from the lexicon. The gaps at hand are thus accidental, rather than systematic.

This article argues that there can only be one chunk-defining device in grammar: a theory cannot afford to have the same work done twice, once by phases, a second time by prosodic constituency. As it stands, however, phase theory is unable to describe all phonologically relevant chunks; these are too small and too diverse to be delineated. To qualify as the only chunk-defining device in grammar, phase theory therefore needs to be made more flexible—that is, to be adapted to the demands of phonology. To allow phase theory to describe all phonologically relevant chunks, we propose the separation of the Spell-Out operation from the Phase Impenetrability Condition (PIC). When Spell-Out occurs, every access point may or may not be associated with a PIC at PF, and the same optional endowment with a PIC holds for syntax. This is what we call Modular PIC. Empirically, on the basis of Abruzzese raddoppiamento fonosintattico and data from Bantu, we show that PIC effects in syntax and phonology are entirely independent: a given Spell-Out operation may leave traces in both modules, in either one, or in neither.