The image of the state of nature has played an important role in political philosophy, international relations, and practical politics for the last several centuries. As the basis of social contract theories, it contributed to the development of the doctrine of government by consent; as a metaphor for the anarchical context in which nation-states relate to each other, it has continuing relevance for theories of international relations and the practice of foreign policy. But how useful is it as a construct for understanding the nature of human beings, the purpose of the states they create, and their political and international relationships? This dissertation answers this question by exploring the state of nature within Immanuel Kant's political philosophy. Uniquely among social contract theorists, Kant rejects both the putatively historical state of nature and the consensual contract. Nonetheless, this dissertation argues not only for his place within the contractarian tradition, but for the philosophical superiority of his treatment of the state of nature in comparison with Thomas Hobbes, John Locke, and Jean-Jacques Rousseau. Kant's metaphysical approach to the state of nature allows him to identify and articulate the moral foundations of such problems as property rights, freedom, coercion, and law, thus insisting on the necessity of the state while still defending republican consent as the ideal political standard. He achieves this on the basis of the essential moral self-awareness of the human person; the perspective the historical state of nature and social contract try to achieve, with less success. Finally, this dissertation examines Kant's logic of the state of nature with regard to states in the international sphere. Here, it is argued that a consistently Kantian approach to international relations results neither in resignation to the international state of nature as a permanent status quo, nor in the imperative to instantiate a world state. Rather, by appealing to the metaphysical approach Kant used at the individual and state level, this dissertation concludes by arguing that states can accept the reality of the international state of nature without viewing such a state as normal or necessary.