This research analyses different interpretations of the philosophy of Immanuel Kant in critical theories of international relations. It argues that, in contrast to conceptions of international theory that restrict its domain to recurrence and to extreme events, Kantianism has laid the groundwork for a broad spectrum of moral and epistemological perspectives on the conditions of possibility for the international and its transformation. Thus, the purpose is a close reading of the dissenting contributions of Andrew Linklater and R. B. J. Walker, whose work has been fundamental in questioning the dominance of realism and liberalism. Apart from the Introduction and the Conclusion, the research is structured in two chapters. Chapter 2 explores Linklater s theory and the transformative role of critique based on Kantian ethics, assessing both the antinomies of Kantianism and Universal Reason and the efforts to modify them through Dialogic Ethics. Chapter 3 reflects on the increasing complexity of the margins and the constitutive outside of modern politics. In contrast to Linklater, Walker interprets Kant as a framer of questions rather than answers, concerning the limits of the international and the concepts of autonomy and sovereignty. Therefore, this research aims to elucidate how Walker and Linklater, in dialogue with Kant, developed their own critical thoughts on the international. Finally, it seeks to contribute to a body of literature that mobilizes Kantianism as an expression of the antinomies of modernity and the entanglement of international relations with moral and social issues.