A view of the morphome debate

This paper surveys the current debate on the morphome, drawing attention to underexplored theoretical possibilities and underexploited empirical tools. We distinguish three related but separate claims made by proponents of the morphome: that there exist morphological patterns mapping arbitrary sets of exponenda onto arbitrary sets of exponents; that such patterns do not suffer from a learnability disadvantage; and that all patterns of exponence are mediated by purely morphological categories belonging to an autonomous level of linguistic representation. We review the problems caused by the lack of positive criteria for morphomicity and by disagreements over the application of negative criteria. We present arguments for a learning bias in favour of realization patterns involving natural classes, and we call for greater use of wug-tests and artificial grammar learning experiments in research on this question. Competing morphological theories turn out to be exhibit a surprising amount of empirical overlap, and their implications for the learnability of morphomic patterns are less straightforward than usually assumed.