Learnability shapes typology: The case of the midpoint pathology

The midpoint pathology (in the sense of Kager 2012) characterizes a type of unattested stress system in which the stressable window contracts to a single word-internal syllable in some words, but not others. Kager (2012) shows that the pathology is a prediction of analyses employing contextual lapse constraints (e.g. *ExtLapseR; no 000 strings at the right edge) and argues that the only way to avoid it is to eliminate these constraints from Con. This article explores an alternative: that systems exhibiting the midpoint pathology are unattested not because the constraints that would generate them are absent from Con, but because they are difficult to learn. This study belongs to a growing body of work exploring the idea that phonological typology is shaped by considerations of learnability.