Unveiling phonological universals: A linguist who asks "why" is (inter alia) an experimental psychologist.

Evans and Levinson are right to hold theories of language accountable for language diversity, but typological data alone cannot determine the structure of mental phonological grammars. Grammatical universals are nonetheless testable by formal and experimental methods, and the growing research in experimental phonology demonstrates the viability of a comparative experimental evaluation of the UG hypothesis.