This thesis is about the debate between Rawls and Hare on moral reasoning and methodology. Its purpose is, firstly, to elucidate the central issues of the debate and, secondly, to reveal what we should focus on when we need to choose which view of them is more adequate to our moral life and reasoning, by uncovering the place of their diverging from each other. In section 2 and 3, Hare's "universal prescritivism" is surveyed and then Rawls' idea of "reflective equilibrium" is surveyed in turn. And in section 4, the difference of uses of intuition between Rawls and Hare is discussed by employing Hare's challenges to Rawls. In section 5, I give Rawls' possible responses to Hare's critiques of him and extract their first fundamental difference between them, that is, their view of the social role of moral viewpoint. And in section 6, Hare's utilitarian consequence and Rawls' non-utilitarian consequence are compared and analyzed through examining Hare's challenges to Rawls. and then in section 7, I extract their second fundamental difference between them, that is, their view of what status person should posses in moral theory and the conception of person as the subject of constructing moral viewpoints and moral realm. In conclusion, I show the first fundamental difference between them is associated with the second one.