Scholars of Kant have long been critical of International Relations’ appropriation of his Toward Perpetual Peace, in particular as it informed democratic peace theory. Now, with democratic backsliding occurring even at the core of the ‘separate peace’ the theory claims developed between democracies, that critique gains newfound salience. This essay demonstrates how the theory is unable to understand democratic backsliding, especially as it is occurring in the United States, but would have been able to if not for misinterpretations of certain substantive elements of Kant’s schema, and, more crucially, a fundamental misunderstanding of the purpose and proper use of it. Grounding a reading of Toward Perpetual Peace more thoroughly in Kant’s philosophical system, I develop the idea of conceiving of and utilizing the essay’s schema in terms of what I call a critical cosmology of peace – a holistic and evolving vision of interrelated practices, conditions, and mechanisms encompassing all of humanity through time and space, and meant mainly to act as a tool of perpetual critique of whatever existing form and degree of democratic peace is currently in existence.