use itself as a mere means or dissolve itself as a moral personality, and should refrain from hostilities during war that would make mutual trust impossible (VIII, 346, 23–5). If there is a duty to sustain oneself as a moral personality, then this implies the duty not to destroy oneself as a physical entity, since the moral, noumenal entity is in need of, and actualized by, a physical one (VI, 422, 31–423, 6). Both the second and the third principle refer to others; Kant admits that there is no difference between the two in terms of content (XXVII, 1, 144, 14–15). They can be distinguished if we assume that the second refers to the state of nature, whereas the third postulates to leave it. Neminem laedere asks moral persons not to injure others, or violate their natural rights (VI, 236, 31–2). In terms of international right, it prohibits war and intervention for reasons of principle.40 The third principle asks individuals or states to leave the state of nature and enter a civil condition (Rechtszustand; VI, 237, 1–8; XXVII, 2, 1, 528, 12–15). In the state of nature, provisional property rights do exist, and this state must be left to secure them, and turn them into peremptory rights (VI, 256).41 The state of nature is, above all, characterized by a certain mode of resolving disputes, namely by private force. One’s own perceived rights and personal judgement is defended with one’s own sword.42 This mode is changed in a juridical condition: modus ius suum persequendi in republica est per actiones non per vim privatum (XIX, refl. 7693).
Kant distinguishes between an active injury (laesio), or violation of a right (VI, 249, 1–3) in a juridical condition and an injury per statum (XIX, refl. 7647). In the state of nature, individuals (or countries) injure each other by this very state in which they coexist, by its ‘very lawlessness’ (Gesetzlosigkeit; VIII, 349, 19), characterized by permanent threats to each other. Anyone is entitled to see neighbours as enemies. Consequently, the state of nature is a state of war, even if there might be a period of tranquillity. As space on earth is limited and often densely populated, humans cannot avoid getting into contact with and influencing each other.43 As a consequence, a state of public right should be instituted. The three definitive articles are based on the postulate that ‘all humans who can at all influence one another must adhere to some kind of civil constitution’ (VIII, 349, 23–4).
The definitive articles institute this juridical condition on three levels: domestic, international and cosmopolitan. These layers are termed civil right, international right (right of nations), and cosmopolitan right. Kant’s classification is indeed logically ‘necessary’ (VIII, 349, 34) and follows from his system of rights. Kant’s reasoning includes only one non-juridical, empirical element. He refers to the earth’s shape and human interaction. ‘Since the earth is a globe’, the third definitive article runs, people ‘cannot disperse over an infinite area’ (VIII, 358, 10–11). This minimalist assumption is plausible, not controversial and does not carry the weight of the argument.44
Some interpreters have spotted a tension between the preliminary and the definitive articles. A reading of the first ‘leads to a realist or statist interpretation that gives primacy to states and governments over individuals’, whereas the definitive articles, above all the third, emphasize the priority of human rights.45 Like similar tensions in Kant’s writings, we can solve this fundamental one by arguing that Kant’s sketch is evolutionary. The preliminary articles are norms for a semi-juridical condition, a condition after the state of nature has been left, but a juridical condition has not yet been fully achieved. Kant is a realist in the sense that he offers a step-by-step-model of how to go beyond the state of nature. He is an idealist because he is not satisfied with the first step(s).
Does Kant expect people to overcome wars and, if he does, what would the future state of affairs be like? Would there be complete harmony, no conflict of interest? Realists will argue that this cannot be achieved, and social Darwinists might add that this goal is not desirable. Humankind would rot to pieces. Kant distinguishes between antagonism and contest on the one hand and war on the other. Contest is the conflict of two or more parties who share a common final end or goal (Endzweck). In case of war, the final ends are opposed to each other (VII, 35, 29–32). Kant envisions a global community where conflicts do not simply disappear, but people have reached a consensus that these conflicts should not be resolved by war. They would share a common final end, namely the rule of law.
The aim of this last section is to demonstrate that a paradigm shift takes place in three areas of Kant’s doctrine of international right. First, it moves from the traditional focus on the right of war (ius belli) to the right directed towards peace (ius pacis). Second, Kant borrows the concept of state sovereignty from international law but reinterprets it as popular sovereignty. Finally, Kant undermines the idea of classical law of nations as almost exclusively centred on states with cosmopolitan right.
Beyond the just-war theory
In the eighteenth century, international law was seen as a system of interactions among sovereign states which did not see each other as criminals but as justi hostes, as potential enemies who (theoretically) shared equal rights.46 Balthazar de Ayala (1548–84) had used iustum in the sense of ‘lawful’ or ‘legal’, pointing out that only the sovereign had the right to wage war.47 By the eighteenth century, war was seen as a duel, as guerre en forme or ‘regular war’,48 which had to fulfil certain formal criteria such as a declaration of war. The question of whether this war was in itself just or not was less important, or even had to be left out:
Thus the rights founded upon the state of war, the legal nature of its effects, the validity of the acquisitions made in it, do not depend, externally and in the sight of men, upon the justice of the cause, but upon the legality of the means as such, that is to say, upon the presence of the elements constituting a regular war.49
This eighteenth-century understanding is fundamentally different from our present perception. Since the First World War, international law has undergone a profound change.50 Modern international law has gradually banned war and the use of force in international relations – at least in theory. The first important document was the Kellogg–Briand Pact of 1928, followed by the Charter of the United Nations of 1945 (article 2, 4). International law has absorbed Kant’s categorical imperative to avoid war and promote peace. This imperative is expressed most clearly in an impressive passage in the Metaphysics of Morals:
[M]oral-practical reason within us pronounces the following irresistible veto: There shall be no war, either between individual human beings in the state of nature, or between separate states … For war is not the way in which anyone should pursue one’s rights. (VI, 354)
This veto is ‘irresistible’, or unwiderstehlich, which means that it does not allow for exceptions. The last sentence in the quotation points out Kant’s philosophical argument: war is the opposite of justice and a just, legal procedure or trial, and thus incapable of obtaining one’s rights. Kant replaces the paradigm of (a formally conducted) war by the paradigm of peace: ‘What is at stake for Kant, is not the elimination of a natural disposition in man to quarrel, but the elimination of possible juridical grounds for it.’51 This is a paradigm shift and can be explained with the help of Hobbes’s formula exeundum e statu naturali. Kant starts with a factual description: states exist ‘in their external relationships with one another … in a condition devoid of right’ (nicht- rechtlichen Zustande; VI, 344, 6–10; VIII, 354–5; VI, 312) and full of (possible) war.52 This seems to be a truism and a banality. In fact, however, it points at the difference between Kant and most of his contemporaries. They tended to question Hobbes’s description of the law of nations as ius inutile and his denial of any binding norms as too extreme or pessimistic. Vattel, for instance, refers to Hobbes’s ‘detestable principles’.53 Kant is completely Hobbesian in his analysis of the status quo. In contrast to Hobbes, however, Kant postulates a juridical duty to leave this state of nature in the sphere of international relations as well (VI, 344, 13–14; VI, 350, 6–8; VIII, 354, 3–8).
Kant’s
