Morpheme Structure Constraints Solve Three Puzzles for Theories of Blocking in Nonderived Environments

In Nonderived Environment Blocking (NDEB), a phonological process applies across morpheme boundaries or morpheme-internally when fed by another phonological process but is otherwise blocked. I present a theory of NDEB that attributes blocking to an interaction between morpheme structure constraints (which constrain possible URs in the lexicon) and the usual phonological mapping from URs to surface forms. The theory has some unusual aspects that make it conceptually suspicious, but I will argue that it receives empirical support. Using several case studies, I discuss three puzzles for theories of NDEB previously proposed in the literature, including the Strict Cycle Condition (Mascaró, 1976), Kiparsky’s (1993) theory of underspecification, Sequential Faithfulness (Burzio, 2000), Coloured Containment (van Oostendorp, 2007), and Optimal Interleaving with Candidate Chains (Wolf, 2008). I show that none of those theories can deal with all three puzzles and that the proposed theory with morpheme structure constraints succeeds. This result supports a dual-component architecture of phonology (as in SPE) over architectures that eliminate language-specific morpheme structure constraints (i.e., the principle of Richness of the Base in Optimality Theory).