Common possession of the earth was a prominent idea in seventeenth-century modern philosophy. In this paper I will argue that Kant not only provides a secularized version of common possession of the earth but also radically departs from the conception of his natural law theory predecessors. I argue that Kant’s account of cosmopolitan right seeks to address the same problem as Grotius’ right of necessity, namely the implausibility of assuming inflexible acquired rights when this would go against the rationale for introducing these rights. However, while Grotius intended to excuse violations of private property in cases of necessity, Kant restricts his discussion to the right of host peoples to reject entrants in their territory. I show that in Kant’s account, to deny life-saving occupation of space to another being who is in principle just as entitled as anyone else to any place of the earth is to contradict the very justification for the territorial rights of states. This is because the permission to control territory and the right of the involuntary visitor to be admitted are based on the same legal foundation or Rechtsgrund, namely, the original community of the earth.