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Legalization of International Politics: On the (Im)Possibility of a Constitutionalization of International Law from a Kantian Point of View

Phillip-Alexander Hirsch



In the debate on the constitutionalization of international law, Kant's work Toward Perpetual Peace is the most important point of reference when talking about the intellectual origin and philosophical background of the idea of constitutionalizing international law. But while it is undeniable that Kant called for a juridification of international relations, it is far less clear which form of juridification Kant aims at. In this essay, I want to show that Kant's ultimate ideal of international law is neither a State of States nor the peace federation (which seems to be commonly accepted), but the cosmopolitan republic, that is, a single homogenous world State. Only such a cosmopolitan republic, backed up by enforceable laws, can be called a constitution in the Kantian sense. Kant's proposal of a peace federation is nothing but a first step towards this ultimate end.

Though it is not a constitution, this peace federation still constitutes a rightful condition insofar as it firstly provides the legal framework for international politics to take place in and at the same time secondly assumes the moral and professional ability of lawyers and politicians in charge to conduct their decisions according to the ultimate ideal of a constitutional world order. International law in the Kantian sense is - as I will demonstrate - thus nothing but a constitutional conduct of government.

Therefore, scholars who call for a constitutionalization of international law in the form of a multi-level legal system or conceive of present regimes, such as the UN, as a constitution are not following Kant in this respect. Under the presumption of sovereign nation States, the only thing we can hope for according to Kant is a legalization of international politics.


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