Discussion Reaffirming the poverty of the stimulus argument: a reply to the replies Jeffrey Lidz a, * , Sandra Waxman b a Department of Linguistics, Northwestern University, 2016 Sheridan Rd., Evanston, IL 60208, USA b Department of Psychology, Northwestern University, 2029 Sheridan Rd., Evanston, IL 60208, USA Received 6 February 2004; accepted 19 February 2004 Abstract Lidz, Waxman, and Freedman [Lidz, J., Waxman, S., & Freedman, J. (2003). What infants know about syntax but couldn’t have learned: Evidence for syntactic structure at 18-months. Cognition, 89, B65 – B73.] argue that acquisition of the syntactic and semantic properties of anaphoric one in English relies on innate knowledge within the learner. Several commentaries have now been published questioning this finding. We defend the original finding by identifying both empirical and logical flaws in the critiques. q 2004 Elsevier B.V. All rights reserved. Keywords: Universal grammar; Poverty of the stimulus; Language acquisition 1. Introduction Fluent use of human language calls for a seamless integration of knowledge from a vast range of sources, both linguistic (e.g. phonology, morphology, syntax, semantics and pragmatics) and nonlinguistic (e.g. conceptual and perceptual representations of objects, events, and ideas; an appreciation of others’ minds and intentions). Surely, in acquiring language, learners must coordinate information from these diverse sources. But just as surely, different aspects of human language depend on these sources to different degrees. For example, sensitivity to the intentions of others likely plays a larger role in determining the meaning of a novel word than in determining the characteristic stress pattern of an exposure language. By the same token, sensitivity to amplitude in the speech signal likely 0022-2860/$ - see front matter q 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.cognition.2004.02.001 Cognition 93 (2004) 157–165 www.elsevier.com/locate/COGNIT * Corresponding author. E-mail address: jlidz@northwestern.edu (J. Lidz).