Perpetual Peace: A Philosophical Sketch

by Immanuel Kant

Whether this satirical inscription on a Dutch innkeeper's sign ("Pax Perpetua" or "Perpetual Peace") upon which a burial ground was painted had for its object mankind in general, or the rulers of states in particular -- who are insatiable of war -- or merely the philosophers who dream this sweet dream, it is not for us to decide. But one condition the author of this essay wishes to lay down. The practical politician assumes the attitude of looking down with great self-satisfaction on the political theorist as a pedant whose empty ideas in no way threaten the security of the state, inasmuch as the state must proceed on empirical principles; so the theorist is allowed to play his game without interference from the worldly-wise statesman. Such being his attitude, the practical politician - and this is the condition I make - should at least act consistently in the case of a conflict and not suspect some danger to the state in the political theorist's opinions which are ventured and publicly expressed without any ulterior purpose. By this clausula salvatoria the author desires formally and emphatically to deprecate herewith any malevolent interpretation which might be placed on his words.


1. "No Treaty of Peace Shall Be Held Valid in Which There Is Tacitly Reserved Matter for a Future War" …

2. "No Independent States, Large or Small, Shall Come under the Dominion of Another State by Inheritance, Exchange, Purchase, or Donation" …

3. "Standing Armies (miles perpetuus) Shall in Time Be Totally Abolished"…

4. "National Debts Shall Not Be Contracted with a View to the External Friction [i.e. warmaking] of States"…

5. "No State Shall by Force Interfere with the Constitution or Government of Another State"

For what is there to authorize it to do so? The offense, perhaps, which a state gives to the subjects of another state? Rather the example of the evil into which a state has fallen because of its lawlessness should serve as a warning. Moreover, the bad example which one free person affords another as a scandalum acceptum is not an infringement of his rights. But it would be quite different if a state, by internal rebellion, should fall into two parts, each of which pretended to be a separate state making claim to the whole. To lend assistance to one of these cannot be considered an interference in the constitution of the other state (for it is then in a state of anarchy) . But so long as the internal dissension has not come to this critical point, such interference by foreign powers would infringe on the rights of an independent people struggling with its internal disease; hence it would itself be an offense and would render the autonomy of all states insecure.

6. "No State Shall, during War, Permit Such Acts of Hostility Which Would Make Mutual Confidence in the Subsequent Peace Impossible: Such Are the Employment of Assassins (percussores), Poisoners (venefici), Breach of Capitulation, and Incitement to Treason (perduellio) in the Opposing State";

These are dishonorable stratagems. For some confidence in the character of the enemy must remain even in the midst of war, as otherwise no peace could be concluded and the hostilities would degenerate into a war of extermination (bellum internecinum). War, however, is only the sad recourse in the state of nature (where there is no tribunal which could judge with the force of law) by which each state asserts its right by violence and in which neither party can be adjudged unjust (for that would presuppose a juridical decision); in lieu of such a decision, the issue of the conflict (as if given by a so-called "judgment of God") decides on which side justice lies. But between states no punitive war (bellum punitivum) is conceivable, because there is no relation between them of master and servant.

It follows that a war of extermination, in which the destruction of both parties and of all justice can result, would permit perpetual peace only in the vast burial ground of the human race. Therefore, such a war and the use of all means leading to it must be absolutely forbidden. But that the means cited do inevitably lead to it is clear from the fact that these infernal arts, vile in themselves, when once used would not long be confined to the sphere of war. Take, for instance, the use of spies (uti exploratoribus). In this, one employs the infamy of others (which can never be entirely eradicated) only to encourage its persistence even into the state of peace, to the undoing of the very spirit of peace.

Although the laws stated are objectively, i.e., in so far as they express the intention of rulers, mere prohibitions (leges prohibitivae), some of them are of that strict kind which hold regardless of circumstances (leges strictae) and which demand prompt execution. Such are Nos. 1, 5, and 6. Others, like Nos. 2, 3, and 4, while not exceptions from the rule of law, nevertheless are subjectively broader (leges latae) in respect to their observation, containing permission to delay their execution without, however, losing sight of the end. This permission does not authorize, under No. 2, for example, delaying until doomsday (or, as Augustus used to say, ad calendas Graecas) the re-establishment of the freedom of states which have been deprived of it - i.e., it does not permit us to fail to do it, but it allows a delay to prevent precipitation which might injure the goal striven for. For the prohibition concerns only the manner of acquisition which is no longer permitted, but not the possession, which, though not bearing a requisite title of right, has nevertheless been held lawful in all states by the public opinion of the time (the time of the putative acquisition).


The state of peace among men living side by side is not the natural state (status naturalis); the natural state is one of war. This does not always mean open hostilities, but at least an unceasing threat of war. A state of peace, therefore, must be established, for in order to be secured against hostility it is not sufficient that hostilities simply be not committed; and, unless this security is pledged to each by his neighbor (a thing that can occur only in a civil state), each may treat his neighbor, from whom he demands this security, as an enemy.


"The Civil Constitution of Every State Should Be Republican";

The only constitution which derives from the idea of the original compact, and on which all juridical legislation of a people must be based, is the republican. This constitution is established, firstly, by principles of the freedom of the members of a society (as men); secondly, by principles of dependence of all upon a single common legislation (as subjects); and, thirdly, by the law of their equality (as citizens). The republican constitution, therefore, is, with respect to law, the one which is the original basis of every form of civil constitution. The only question now is: Is it also the one which can lead to perpetual peace?

The republican constitution, besides the purity of its origin (having sprung from the pure source of the concept of law), also gives a favorable prospect for the desired consequence, i.e., perpetual peace. The reason is this: if the consent of the citizens is required in order to decide that war should be declared (and in this constitution it cannot but be the case), nothing is more natural than that they would be very cautious in commencing such a poor game, decreeing for themselves all the calamities of war. Among the latter would be: having to fight, having to pay the costs of war from their own resources, having painfully to repair the devastation war leaves behind, and, to fill up the measure of evils, load themselves with a heavy national debt that would embitter peace itself and that can never be liquidated on account of constant wars in the future. But, on the other hand, in a constitution which is not republican, and under which the subjects are not citizens, a declaration of war is the easiest thing in the world to decide upon, because war does not require of the ruler, who is the proprietor and not a member of the state, the least sacrifice of the pleasures of his table, the chase, his country houses, his court functions, and the like. He may, therefore, resolve on war as on a pleasure party for the most trivial reasons, and with perfect indifference leave the justification which decency requires to the diplomatic corps who are ever ready to provide it.

In order not to confuse the republican constitution with the democratic (as is commonly done), the following should be noted. The forms of a state (civitas) can be divided either according to the persons who possess the sovereign power or according to the mode of administration exercised over the people by the chief, whoever he may be. The first is properly called the form of sovereignty (forma imperii), and there are only three possible forms of it: autocracy, in which one, aristocracy, in which some associated together, or democracy, in which all those who constitute society, possess sovereign power. They may be characterized, respectively, as the power of a monarch, of the nobility, or of the people. The second division is that by the form of government (forma regiminis) and is based on the way in which the state makes use of its power; this way is based on the constitution, which is the act of the general will through which the many persons become one nation. In this respect government is either republican or despotic. Republicanism is the political principle of the separation of the executive power (the administration) from the legislative; despotism is that of the autonomous execution by the state of laws which it has itself decreed. Thus in a despotism the public will is administered by the ruler as his own will. Of the three forms of the state, that of democracy is, properly speaking, necessarily a despotism, because it establishes an executive power in which "all" decide for or even against one who does not agree; that is, "all," who are not quite all, decide, and this is a contradiction of the general will with itself and with freedom.

...And even though the other two constitutions are always defective to the extent that they do leave room for this mode of administration, it is at least possible for them to assume a mode of government conforming to the spirit of a representative system (as when Frederick II at least said he was merely the first servant of the state). On the other hand, the democratic mode of government makes this impossible, since everyone wishes to be master. Therefore, we can say: the smaller the personnel of the government (the smaller the number of rulers), the greater is their representation and the more nearly the constitution approaches to the possibility of republicanism; thus the constitution may be expected by gradual reform finally to raise itself to republicanism. For these reasons it is more difficult for an aristocracy than for a monarchy to achieve the one completely juridical constitution, and it is impossible for a democracy to do so except by violent revolution.

The mode of governments, however, is incomparably more important to the people than the form of sovereignty, although much depends on the greater or lesser suitability of the latter to the end of [good] government. To conform to the concept of law, however, government must have a representative form, and in this system only a republican mode of government is possible; without it, government is despotic and arbitrary, whatever the constitution may be. None of the ancient so-called "republics" knew this system, and they all finally and inevitably degenerated into despotism under the sovereignty of one, which is the most bearable of all forms of despotism.


"The Law of Nations Shall be Founded on a Federation of Free States";

Peoples, as states, like individuals, may be judged to injure one another merely by their coexistence in the state of nature (i.e., while independent of external laws). Each of then, may and should for the sake of its own security demand that the others enter with it into a constitution similar to the civil constitution, for under such a constitution each can be secure in his right. This would be a league of nations, but it would not have to be a state consisting of nations. That would be contradictory, since a state implies the relation of a superior (legislating) to an inferior (obeying), i.e., the people, and many nations in one state would then constitute only one nation. This contradicts the presupposition, for here we have to weigh the rights of nations against each other so far as they are distinct states and not amalgamated into one.

When we see the attachment of savages to their lawless freedom, preferring ceaseless combat to subjection to a lawful constraint which they might establish, and thus preferring senseless freedom to rational freedom, we regard it with deep contempt as barbarity, rudeness, and a brutish degradation of humanity. Accordingly, one would think that civilized people (each united in a state) would hasten all the more to escape, the sooner the better, from such a depraved condition. But, instead, each state places its majesty (for it is absurd to speak of the majesty of the people) in being subject to no external juridical restraint, and the splendor of its sovereign consists in the fact that many thousands stand at his command to sacrifice themselves for something that does not concern them and without his needing to place himself in the least danger. The chief difference between European and American savages lies in the fact that many tribes of the latter have been eaten by their enemies, while the former know how to make better use of their conquered enemies than to dine off them; they know better how to use them to increase the number of their subjects and thus the quantity of instruments for even more extensive wars.

When we consider the perverseness of human nature which is nakedly revealed in the uncontrolled relations between nations (this perverseness being veiled in the state of civil law by the constraint exercised by government), we may well be astonished that the word "law" has not yet been banished from war politics as pedantic, and that no state has yet been bold enough to advocate this point of view. Up to the present, Hugo Grotius, Pufendorf, Vattel, and many other irritating comforters have been cited in justification of war, though their code, philosophically or diplomatically formulated, has not and cannot have the least legal force, because states as such do not stand under a common external power. There is no instance on record that a state has ever been moved to desist from its purpose because of arguments backed up by the testimony of such great men. But the homage which each state pays (at least in words) to the concept of law proves that there is slumbering in man an even greater moral disposition to become master of the evil principle in himself (which he cannot disclaim) and to hope for the same from others. Otherwise the word "law" would never be pronounced by states which wish to war upon one another; it would be used only ironically, as a Gallic prince interpreted it when he said, "It is the prerogative which nature has given the stronger that the weaker should obey him."

States do not plead their cause before a tribunal; war alone is their way of bringing suit. But by war and its favorable issue, in victory, right is not decided, and though by a treaty of peace this particular war is brought to an end, the state of war, of always finding a new pretext to hostilities, is not terminated. Nor can this be declared wrong, considering the fact that in this state each is the judge of his own case. Notwithstanding, the obligation which men in a lawless condition have under the natural law, and which requires them to abandon the state of nature, does not quite apply to states under the law of nations, for as states they already have an internal juridical constitution and have thus outgrown compulsion from others to submit to a more extended lawful constitution according to their ideas of right. This is true in spite of the fact that reason, from its throne of supreme moral legislating authority, absolutely condemns war as a legal recourse and makes a state of peace a direct duty, even though peace cannot be established or secured except by a compact among nations.
For these reasons there must be a league of a particular kind, which can be called a league of peace (foedus pacificum), and which would be distinguished from a treaty of peace (pactum pacis) by the fact that the latter terminates only one war, while the former seeks to make an end of all wars forever. This league does not tend to any dominion over the power of the state but only to the maintenance and security of the freedom of the state itself and of other states in league with it, without there being any need for them to submit to civil laws and their compulsion, as men in a state of nature must submit.

The practicability (objective reality) of this idea of federation, which should gradually spread to all states and thus lead to perpetual peace, can be proved. For if fortune directs that a powerful and enlightened people can make itself a republic, which by its nature must be inclined to perpetual peace, this gives a fulcrum to the federation with other states so that they may adhere to it and thus secure freedom under the idea of the law of nations. By more and more such associations, the federation may be gradually extended.

We may readily conceive that a people should say, "There ought to be no war among us, for we want to make ourselves into a state; that is, we want to establish a supreme legislative, executive, and judiciary power which will reconcile our differences peaceably." But when this state says, "There ought to be no war between myself and other states, even though I acknowledge no supreme legislative power by which our rights are mutually guaranteed," it is not at all clear on what I can base my confidence in my own rights unless it is the free federation, the surrogate of the civil social order, which reason necessarily associates with the concept of the law of nations - assuming that something is really meant by the latter.

The concept of a law of nations as a right to make war does not really mean anything, because it is then a law of deciding what is right by unilateral maxims through force and not by universally valid public laws which restrict the freedom of each one. The only conceivable meaning of such a law of nations might be that it serves men right who are so inclined that they should destroy each other and thus find perpetual peace in the vast grave that swallows both the atrocities and their perpetrators. For states in their relation to each other, there cannot be any reasonable way out of the lawless condition which entails only war except that they, like individual men, should give up their savage (lawless) freedom, adjust themselves to the constraints of public law, and thus establish a continuously growing state consisting of various nations (civitas gentium), which will ultimately include all the nations of the world. But under the idea of the law of nations they do not wish this, and reject in practice what is correct in theory. If all is not to be lost, there can be, then, in place of the positive idea of a world republic, only the negative surrogate of an alliance which averts war, endures, spreads, and holds back the stream of those hostile passions which fear the law, though such an alliance is in constant peril of their breaking loose again. Furor impius intus . . . fremit horridus ore cruento (Virgil).


"The Law of World Citizenship Shall Be Limited to Conditions of Universal Hospitality";

Here, as in the preceding articles, it is not a question of philanthropy but of right. Hospitality means the right of a stranger not to be treated as an enemy when he arrives in the land of another. One may refuse to receive him when this can be done without causing his destruction; but, so long as he peacefully occupies his place, one may not treat him with hostility. It is not the right to be a permanent visitor that one may demand. A special beneficent agreement would be needed in order to give an outsider a right to become a fellow inhabitant for a certain length of time. It is only a right of temporary sojourn, a right to associate, which all men have. They have it by virtue of their common possession of the surface of the earth, where, as a globe, they cannot infinitely disperse and hence must finally tolerate the presence of each other. Originally, no one had more right than another to a particular part of the earth.

Uninhabitable parts of the earth - the sea and the deserts - divide this community of all men, but the ship and the camel (the desert ship) enable them to approach each other across these unruled regions and to establish communication by using the common right to the face of the earth, which belongs to human beings generally. The inhospitality of the inhabitants of coasts (for instance, of the Barbary Coast) in robbing ships in neighboring seas or enslaving stranded travelers, or the inhospitality of the inhabitants of the deserts (for instance, the Bedouin Arabs) who view contact with nomadic tribes as conferring the right to plunder them, is thus opposed to natural law, even though it extends the right of hospitality, i.e., the privilege of foreign arrivals, no further than to conditions of the possibility of seeking to communicate with the prior inhabitants. In this way distant parts of the world can come into peaceable relations with each other, and these are finally publicly established by law. Thus the human race can gradually be brought closer and closer to a constitution establishing world citizenship.

But to this perfection compare the inhospitable actions of the civilized and especially of the commercial states of our part of the world. The injustice which they show to lands and peoples they visit (which is equivalent to conquering them) is carried by them to terrifying lengths. America, the lands inhabited by the Negro, the Spice Islands, the Cape, etc., were at the time of their discovery considered by these civilized intruders as lands without owners, for they counted the inhabitants as nothing. In East India (Hindustan), under the pretense of establishing economic undertakings, they brought in foreign soldiers and used them to oppress the natives, excited widespread wars among the various states, spread famine, rebellion, perfidy, and the whole litany of evils which afflict mankind.

China and Japan (Nippon), who have had experience with such guests, have wisely refused them entry, the former permitting their approach to their shores but not their entry, while the latter permit this approach to only one European people, the Dutch, but treat them like prisoners, not allowing them any communication with the inhabitants. The worst of this (or, to speak with the moralist, the best) is that all these outrages profit them nothing, since all these commercial ventures stand on the verge of collapse, and the Sugar Islands, that place of the most refined and cruel slavery, produces no real revenue except indirectly, only serving a not very praiseworthy purpose of furnishing sailors for war fleets and thus for the conduct of war in Europe. This service is rendered to powers which make a great show of their piety, and, while they drink injustice like water, they regard themselves as the elect in point of orthodoxy.

Since the narrower or wider community of the peoples of the earth has developed so far that a violation of rights in one place is felt throughout the world, the idea of a law of world citizenship is no high-flown or exaggerated notion. It is a supplement to the unwritten code of the civil and international law, indispensable for the maintenance of the public human rights and hence also of perpetual peace. One cannot flatter oneself into believing one can approach this peace except under the condition outlined here.


The guarantee of perpetual peace is nothing less than that great artist, nature (natura daedala rerum). In her mechanical course we see that her aim is to produce a harmony among men, against their will and indeed through their discord…

Now we come to the question concerning that which is most essential in the design of perpetual peace: What has nature done with regard to this end which man's own reason makes his duty? That is, what has nature done to favor man's moral purpose, and how has she guaranteed (by compulsion but without prejudice to his freedom) that he shall do that which he ought to but does not do under the laws of freedom? This question refers to all three phases of public law, namely, civil law, the law of nations, and the law of world citizenship. If I say of nature that she wills that this or that occur, I do not mean that she imposes a duty on us to do it, for this can be done only by free practical reason; rather I mean that she herself does it, whether we will or not (fata volentem ducunt, nolentem trahunt ["Fates lead the willing, drive the unwilling" (Seneca Epist. mor. XVIII.)]

1. Even if a people were not forced by internal discord to submit to public laws, war would compel them to do so, for we have already seen that nature has placed each people near another which presses upon it, and against this it must form itself into a state in order to defend itself. Now the republican constitution is the only one entirely fitting to the rights of man. But it is the most difficult to establish and even harder to preserve, so that many say a republic would have to be a nation of angels, because men with their selfish inclinations are not capable of a constitution of such sublime form. But precisely with these inclinations nature comes to the aid of the general will established on reason, which is revered even though impotent in practice. Thus it is only a question of a good organization of the state (which does lie in man's power), whereby the powers of each selfish inclination are so arranged in opposition that one moderates or destroys the ruinous effect of the other. The consequence for reason is the same as if none of them existed, and man is forced to be a good citizen even if not a morally good person.

The problem of organizing a state, however hard it may seem, can be solved even for a race of devils, if only they are intelligent. The problem is: "Given a multitude of rational beings requiring universal laws for their preservation, but each of whom is secretly inclined to exempt himself from them, to establish a constitution in such a way that, although their private intentions conflict, they check each other, with the result that their public conduct is the same as if they had no such intentions."

A problem like this must be capable of solution; it does not require that we know how to attain the moral improvement of men but only that we should know the mechanism of nature in order to use it on men, organizing the conflict of the hostile intentions present in a people in such a way that they must compel themselves to submit to coercive laws. Thus a state of peace is established in which laws have force. We can see, even in actual states, which are far from perfectly organized, that in their foreign relations they approach that which the idea of right prescribes. This is so in spite of the fact that the intrinsic element of morality is certainly not the cause of it. (A good constitution is not to be expected from morality, but, conversely, a good moral condition of a people is to be expected only under a good constitution.) Instead of genuine morality, the mechanism of nature brings it to pass through selfish inclinations, which naturally conflict outwardly but which can be used by reason as a means for its own end, the sovereignty of law, and, as concerns the state, for promoting and securing internal and external peace.

This, then, is the truth of the matter: Nature inexorably wills that the right should finally triumph. What we neglect to do comes about by itself, though with great inconveniences to us. "If you bend the reed too much, you break it; and he who attempts too much attempts nothing" (Bouterwek).

2. The idea of international law presupposes the separate existence of many independent but neighboring states. Although this condition is itself a state of war (unless a federative union prevents the outbreak of hostilities), this is rationally preferable to the amalgamation of states under one superior power, as this would end in one universal monarchy, and laws always lose in vigor what government gains in extent; hence a soulless despotism falls into anarchy after stifling the seeds of the good.

Nevertheless, every state, or its ruler, desires to establish lasting peace in this way, aspiring if possible to rule the whole world. But nature wills otherwise. She employs two means to separate peoples and to prevent them from mixing: differences of language and of religion. These differences involve a tendency to mutual hatred and pretexts for war, but the progress of civilization and men's gradual approach to greater harmony in their principles finally leads to peaceful agreement. This is not like that peace which despotism (in the burial ground of freedom) produces through a weakening of all powers; it is, on the contrary, produced and maintained by their equilibrium in liveliest competition.

3. Just as nature wisely separates nations, which the will of every state, sanctioned by the principles of international law, would gladly unite by artifice or force, nations which could not have secured themselves against violence and war by means of the law of world citizenship unite because of mutual interest. The spirit of commerce, which is incompatible with war, sooner or later gains the upper hand in every state. As the power of money is perhaps the most dependable of all the powers (means) included under the state power, states see themselves forced, without any moral urge, to promote honorable peace and by mediation to prevent war wherever it threatens to break out. They do so exactly as if they stood in perpetual alliances, for great offensive alliances are in the nature of the case rare and even less often successful.

In this manner nature guarantees perpetual peace by the mechanism of human passions. Certainly she does not do so with sufficient certainty for us to predict the future in any theoretical sense, but adequately from a practical point of view, making it our duty to work toward this end, which is not just a chimerical one.


A secret article in contracts under public law is objectively, i.e., from the standpoint of its content, a contradiction. Subjectively, however, a secret clause can be present in them, because the persons who dictate it might find it compromising to their dignity to declare openly that they are its authors.

The only article of this kind is contained in the statement: "The opinions of philosophers on the conditions of the possibility of public peace shall be consulted by those states armed for war."

But it appears humiliating to the legislative authority of a state, to whom we must naturally attribute the utmost wisdom, to seek instruction from subjects (the philosophers) on principles of conduct toward other states. It is nevertheless very advisable to do so. Therefore, the state tacitly and secretly invites them to give their opinions, that is, the state will let them publicly and freely talk about the general maxims of warfare and of the establishment of peace (for they will do that of themselves, provided they are not forbidden to do so). It does not require a particular convention among states to see that this is done, since their agreement on this point lies in an obligation already established by universal human reason which is morally legislative…

That kings should philosophize or philosophers become kings is not to be expected. Nor is it to be wished, since the possession of power inevitably corrupts the untrammeled judgment of reason. But kings or kinglike peoples which rule themselves under laws of equality should not suffer the class of philosophers to disappear or to be silent, but should let them speak openly. This is indispensable to the enlightenment of the business of government, and, since the class of philosophers is by nature incapable of plotting and lobbying, it is above suspicion of being made up of propagandists.


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