Immanuel Kant

Kant's second definitive article (*Toward Perpetual Peace*, 1795) holds that the law of nations should rest on a *federation* of free republics, not a single super-state, because a world government would either collapse into despotism or dissolve. Peace is a standing institution voluntarily maintained by states that retain sovereignty but bind themselves to a pacific union (Sweet 2018, DOI:10.1093/oso/9780198825340.003.0002). **Test it imposes:** does a proposed space-governance regime seek durable order through a *federated* arrangement of sovereign actors who keep their autonomy while accepting common constraints, or does it assume either a hegemonic enforcer (a de facto world state) or no institution at all? Kant rejects both poles; he demands the middle structure.

Kant's first definitive article requires that the civil constitution of each state be *republican*: founded on freedom, a single common legislation, and the consent of those who bear the costs of war. The mechanism is incentive-alignment, not virtue: where those who must pay and fight must also consent, war becomes hard to launch. Modern democratic-peace theory descends from this article but has substituted commerce for Kant's third prescription, producing a theory in tension with its source (Simpson 2018, DOI:10.1177/0047117818811463). **Test:** does the candidate's regime align the decision rights with the cost-bearers, so that the actors empowered to escalate are the ones who absorb the consequences? A regime that lets some actors externalize the costs of their behavior onto all users has violated the republican principle.

In Appendix II of *Perpetual Peace*, Kant gives a procedural test of justice: "All actions relating to the right of other men are unjust if their maxim is not consistent with publicity." A policy that *cannot survive being made public* - that depends on concealment to succeed - is for that reason wrong and unstable. In the contemporary idiom this is the moral root of transparency-and-confidence-building measures (TCBMs) in space security (Robinson 2016, DOI:10.1016/j.spacepol.2016.11.003; UN GGE 2014, DOI:10.18356/62b1be29-en). **Test:** would the candidate's plan, behavior, or architecture survive full disclosure to all affected parties? If its workability depends on opacity (undeclared maneuvers, ambiguous dual-use intent, hidden keep-out claims), Kant judges it unjust and predicts it will breed counter-measures rather than stability.

Kant's third definitive article limits cosmopolitan right to *universal hospitality*: because the Earth's surface is finite and originally held in common, no one has a superior right to a place on it, and strangers have a right not to be treated with hostility on arrival - but this is a right of *resort and conditional access*, not a right of conquest or settlement. The finitude of the shared surface is doing the work. **Test:** does the candidate treat a finite, commonly held space resource (orbital volume, spectrum, a Peak of Eternal Light, a cislunar corridor) as subject to a right of *conditioned common access*, or does it license de facto appropriation that forecloses others? Kant's principle forbids turning first arrival into exclusive title.

Before the definitive articles, Kant lists prohibitions - no peace treaty with a secret reservation of future war, standing armies should in time be abolished, no state shall forcibly interfere in another's constitution, and no acts of war shall be permitted that would make mutual confidence impossible in the eventual peace. These are *confidence-preserving constraints*: they ban the moves that destroy the trust a federation needs to function. **Test:** does the architecture avoid the trust-destroying moves - the hidden reservation, the destabilizing capability buildup, the irreversible act that poisons future cooperation (e.g., debris-generating ASAT tests)? A regime that tolerates confidence-destroying acts cannot sustain the federation that its peace requires.