Immanuel Kant and the Myth of Perpetual Peace

Immanuel Kant and the Myth of Perpetual Peace

Can the procedures of democratic decisionmaking offer a constitutional solution to the problem of war?

Perhaps more than any other philosopher, Immanuel Kant has suffered the praise of having been labeled an historical optimist. Kant’s writings on international affairs have been misconstrued as a defense of the both the desirability and inevitability of a world federation of democracies bound by law. This rendering of Kant has been aided by a selective attention to a few key works and a cultivated ignorance of his more pessimistic remarks on the human condition elsewhere. The truth is that Kant’s theory of international affairs is complicated, eluding clean classification as “realist” or “liberal,” but altogether gloomier than is commonly thought. Although the optimist may dream of perpetual peace, no such harmony can be hewn from “the crooked timber of humanity.” Kant’s view of history is in fact quite pessimistic, and his prescriptions for politics are in many ways consistent with the realist paradigm. Mankind faces a Sisyphean task: an unending struggle between the universal and particular, harmony and multiplicity, sympathy and antagonism.

The case for Kant-as-liberal-optimist is straightforward: in Perpetual Peace and the Doctrine of Right , he speaks of the condition of injustice in which states find themselves, arranged in an international anarchy with no higher authority. Like the state of nature among individuals, states are subjected to the unilateral whims of their potential adversaries, a condition formally incompatible with the duty to respect each as an end-in-itself. Just as men must overcome this anarchic condition of injustice by establishing a civil state, states must institute an international legal order in the form of a federation of states submitting to a common adjudicative authority.  Only then can coercion become regulated in the international sphere and represent the omnilateral will of the human race, just as the state represents the will of its people.

If only states were to submit to this regime, war might be done away with. This, however, is possible only in a federation of republics, since they alone will be constituted in a way to abolish the motive for war. Here is the origin of the “democratic peace” doctrine Kant purportedly advanced: for any state with a democratic constitution, “the consent of the citizens . . . is required to determine . . . ‘Whether there shall be war or not?’ Hence, nothing is more natural than that they should be very loth to enter upon so undesirable an undertaking, for . . . they would necessarily be resolving to bring upon themselves all the horrors of War.” Only a democratic world order, in which each state’s population internalizes the costs of its own behavior, can organize itself into a liberal world order in which states are regulated by law.

And yet Kant is elsewhere less sanguine about the prospects for peace. He claims in the Doctrine of Right that “perpetual peace, the ultimate goal of the whole right of nations, is indeed an unachievable idea”—“idea,” as we will soon see, being the operative word. He even characterizes the history of the human race as afflicted by an unavoidable antagonism which cannot—and indeed should not—be cured. Is Kant simply an incoherent thinker, at times a hopeful liberal, elsewhere a pessimist?

We must first understand Kant’s conception of humanity as participating in two worlds, the sensuous and intelligible. Man is at once rational and free, therefore subject to laws of reason and accountable for his actions, and also prone to sensual inclinations, therefore liable to disobey his rational duties when given over to temptation. To say that man ought to act in some way is not to say that he will, but only that, from the practical point of view of free choice, he can and should. A purely rational being, a Holy Will, devoid of sensuous content, could only ever affirm the laws of reason. Animals, on the other hand, obey their instincts and are incapable of freedom and, for this reason, morality also. Man alone is capable of both recognizing the moral law and choosing to disobey it, and it is for this reason that Kant claims that people are by nature evil.


Whether by weakness of will, impurity of motive, or the radical evil of freely choosing immorality, man lives in a fallen condition, inflicting himself on humanity with a cruelty unseen even in beasts. As evidence, Kant offers “international affairs where civilized nations stand vis-à-vis one another in a relationship of a raw state of nature (a continuing state of war), and are firmly resolved never to depart from that . . . This is so much the case that the philosophical chiliasm, who hoped for a state of perpetual peace based on a federation of nations as a world republic, was ridiculed as mentally raptured.” Concupiscence, the inclination toward sin that rests at the base of man’s soul, is incurable, playing itself out time and again in the bloody annals of history. Kant’s judgment is fatalistic, for “as long as a state has another adjacent state which it might hope to subdue, it strives to enlarge itself through the subjugation of this other, and therefore also to make itself a universal monarchy . . . But this monster . . . after having swallowed all neighboring states, finally dissolves of itself and separates through uproar and discord into many smaller states which, instead of striving toward a union of states (a republic of free, allied peoples), simply and of itself starts the process all over again in order never to cease the war.”