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 underlying representations in the lexicon) and the usual phonological mapping from underlying 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 (Mascarό 1976), Kiparsky’s (1993) theory of underspecification, Sequential Faithfulness (Burzio 2000), Colored 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 Chomsky and Halle 1968) over architectures that eliminate language-specific morpheme structure constraints (i.e., the principle of Richness of the Base in Optimality Theory).