Cognitive linguists argue that certain sets of knowledge of language are innate. However, critics have argued that the theoretical concept of "innateness" should be eliminated since it is ambiguous and insubstantial. In response, I aim to strengthen theories of language acquisition and identify ways to make them more substantial. I review the Poverty of Stimulus argument and separate it into four nonequivalent arguments: Deficiency of Stimulus, Corruption of Stimulus, Variety of Stimulus, and Poverty of Negative Evidence. Each argument uses a disparate set of empirical observations to support different conclusions about the traits that are claimed to be innate. Separating the Poverty of Stimulus arguments will aid in making each one more effective. I offer three sets of considerations that scholars can use to strengthen linguistic theories. The Empirical Consideration urges scholars to address specific sets of empirical observations, thus ensuring that innateness theories are not used to explain dissimilar traits. The Developmental Consideration urges scholars to consider complex developmental processes of acquisition. The Interaction Consideration urges scholars to examine interactions between organisms and their environment during language acquisition. I support recent contributions to the approach of "biologicizing the mind" which encourages interdisciplinary collaboration between psychology and biology. I develop an account of language acquisition in terms of canalization, and use this account to explain empirical observations used in Variety of Stimulus arguments. Finally, I argue that the conception of "innateness" can be understood in terms of canalization when it applies to traits that are canalized. Although the canalization conception of "innateness" is not generalizable, it can explain a certain set of empirical observations about language acquisition. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com/en-US/products/dissertations/individuals.shtml.]