This work demonstrates that one can accept Heidegger's radically new conception of human subjectivity without being committed to the negative social ontology that is often deemed to be its direct consequence. Heidegger rejects traditional theories of intersubjectivity because they characterize the self as a type of isolated, independent substance that is required to 'bridge the gap' to reach or recognize others like itself. In contrast, Heidegger argues that the self is defined by a fundamental sociality expressed by its immersion in shared public roles and norms. In doing so, however, he opens himself up to a long-standing critique: namely, by simply stipulating subjectivity's sociality, Heidegger grants it the status of an a priori category which cannot accommodate immediate experiences of others in their concrete particularity; others are simply interchangeable tokens whose uniqueness is subsumed under the generality of the established category. By engaging in an analysis of the nature of the a priori in Heidegger's work, I demonstrate that this 'social category' is in fact a responsiveness to the other in her unique temporal particularity. On this basis, I am able to provide a Heidegger-inspired account of respect and the origins of normativity. My dissertation thus provides a significantly different approach to Heidegger interpretation, and compensates for shortcomings in contemporary theories of intersubjectivity.