L. S. Vygotsky's contributions to social research shifted paradigms by constructing now-foundational theories of teaching, learning, language, and their educational interactions. This article contextualizes a nearly forgotten, century-old research corpus, "The Fundamentals of Defectology." Drawing on "Defectology," two dialectic arguments are developed, which synthesize Vygotsky's corpus, then juxtaposed it against contemporary theories and evidence. The first describes three principles of Vygotsky's framework for deaf pedagogy: positive differentiation, creative adaptation, and dynamic development. The second posits five propositions about deaf development: the biosocial proposition, the sensory delimitation-and-consciousness proposition, the adapted tools proposition, the multimodal proposition, and the conflict proposition. By leveraging Vygotsky's optimism in response to the absorbing and difficult challenges of experimental, methodological, and theoretical research about deafness, including the psychology of disability and special methods of pedagogy, both arguments constitute a future-oriented call to action for researchers and pedagogues working in deaf education today.