Peter W. Culicover is Chair of the Department of Linguistics and former Director of the Center for Cognitive Science at the Ohio State University. His books include Formal Principles of Language Acquisition (1980, with Kenneth Wexler), Principles and Parameters (1997), Syntactic Nuts (1999), and Dynamical Grammar (2003, with Andrzej Nowak). Ray Jackendoff is Professor of Philosophy and Co-director of the Center for Cognitive Studies at Tufts University. He was previously Professor of Linguistics at Brandeis University. His books include Semantics and Cognition (1983), Consciousness and