Who is the subject of habitual activity, and who, if anyone, is morally responsible for such actions? Following Saint Paul, Saint Augustine taught that it is ‘not I’ who am responsible for my habitual acts, but ‘sin, which inhabits me,’ sin derived from Adam's ‘original’ sin. Centuries later, Martin Heidegger argues that the ‘who’ of our everyday habitual existence is not the ‘authentic self,’ but the ‘they-self,’ the inauthentic self entangled in and guided by the anonymous forces of social normativity. This dissertation analyzes the early Christian account of ‘original sin’ and its hitherto unappreciated iteration in Heidegger's existential account of ‘fallenness.’ Heiner argues that this vestige of the anthropology of Christian theology undermines the post-metaphysical intentions of Being and Time, as well as its purported normative neutrality, leading it to a manifestly disembodied, though latently gendered, account of authentic selfhood. Being and Time, it is argued, remains caught in the ambit of masculinist and militaristic notions of moral responsibility that privilege ideals of mastery over solidarity, autonomy over relationality, and that rely for their coherence on a feminized construction of habitual and social bodily being against which the virile authentic individual wages a daily war. After examining the descriptive and normative deficiencies of this genealogy in Chapters One and Two, the dissertation turns to feminist and phenomenological philosophy on the intentionality and sociality of habitual bodies to offer an account of moral responsibility based in specifically bodily dimensions of social solidarity. Building upon Maurice Merleau-Ponty's notion of the corporeal self as ‘an intersubjective field’ that is ‘centered outside itself’ as well as on Judith Butler's figuration of gender identity as ‘a stylized repetition of acts through time,’ Chapter Three argues that responsibility is not grounded in the autonomous upheaval of a disembodied ‘resolution’ (Heidegger), but in the prelinguistic and prereflective dynamics of bodily beings in a shared social-practical world.