Phonological exceptionality is localized to phonological elements: the argument from learnability and Yidiny word-final deletion

Anderson (2008) emphasizes that the space of possible grammars must be constrained by limits not only on what is cognitively representable, but on what is learnable. Focusing on word final deletion in Yidiny (Dixon 1977), I show that the learning of exceptional phonological patterns is improved if we assume that Prince & Tesar's (2004) Biased Constraint Demotion (BCD) with Constraint Cloning (Pater 2009) is subject to a Morphological Coherence Principle (MCP), which operationalizes morphological analytic bias (Moreton 2008) during phonological learning. The existence of the MCP allows the initial state of CON to be simplified, and thus shifts explanatory weight away from the representation of the grammar per se, and towards the learning device. I then argue that the theory of exceptionality must be phonological and diacritic. Specifically, I show that co-indexation between lexical forms and lexically indexed constraints must be via indices not on morphs but on individual phonological elements. Relative to indices on phonological elements, indices on morphs add computational cost for no benefit during constraint evaluation and learning; and a theory without indices on phonological elements is empirically insufficient. On the other hand, approaches which represent exceptionality by purely phonological means (e.g. Zoll 1996) are ill-suited to efficient learning. Concerns that a phonologically-indexed analysis would overgenerate (Gouskova 2012) are unfounded under realistic assumptions about the learner