A theory of conceptual development must provide an account of the innate representational repertoire, must characterize how these initial representations differ from the adult state, and must provide an account of the processes that transform the initial into mature representations. In Carey, 2009 (The Origin of Concepts), I defend three theses: 1) the initial state includes rich conceptual representations, 2) nonetheless, there are radical discontinuities between early and later developing conceptual systems, 3) Quinean bootstrapping is one learning mechanism that underlies the creation of new representational resources, enabling such discontinuity. I also claim that the theory of conceptual development developed in The Origin of Concepts addresses two of Fodor's challenges to cognitive science; namely, to show how learning could possibly lead to an increase in expressive power and to defeat Mad Dog Nativism, the thesis that all concepts lexicalized as mono-morphemic words are innate. A recent article by Georges Rey (Mind & Language, 29.2, 2014) argues that my responses to Fodor's challenges fail, because, he says, I fail to distinguish concept possession from manifestation and I do not confront Goodman's new riddle of induction. My response is to show that, and how, new primitives in a language of thought can be learned, that there are easy routes and hard ones to doing so, and that characterizing the learning mechanisms involved is the key to understanding both concept possession and constraints on induction.Thanks to Georges Rey for many discussions of the points that articulate our debates, to Ned Block and Jake Beck for comments on earlier drafts of this reply to Rey, and to Samuel Guttenplan and a blind reviewer for helpful criticisms and suggestions. characterize the learning mechanisms that achieve the transformation of the initial into the final state. The Origin of Concepts (henceforth TOOC) defends three theses. With respect to the initial state, contrary to historically important thinkers such as the British empiricists, Quine, and Piaget, as well as many contemporary scientists, the innate stock of primitives is not limited to sensory, perceptual or sensorymotor representations; rather, there are also rich innate conceptual representations with contents such as object, agent, goal, cause, and approximate cardinal value of a set of individuals (part of what makes the human conceptual repertoire possible). With respect to developmental change, contrary to 'continuity theorists' such as Fodor, Pinker, Rey and others, conceptual development involves qualitative change, resulting in systems of representation that are more powerful than, and sometimes incommensurable with, those from which they are built (part of what makes attaining the human conceptual repertoire sometimes hard). With respect to a learning mechanism that achieves conceptual discontinuity, I offer Quinean bootstrapping (part of what makes attaining the human conceptual repertoire possible.)While the goal of TOOC was to explicate and def...