In his essay “Perpetual Peace (1795), Immanuel Kant continued a theme that he had discussed two years earlier in “On the Proverb: That May be True in Theory but it is of No Practical Use” (1793). Kant had no patience with the claim—which remains common to this day—that philosophical principles have little if any relevance to the real world of practical actions. Kant regarded this belief as especially pernicious in the realm of politics, as when politicians claim that moral principles cannot realistically be applied to the ruthless and frequently violent interactions between sovereign nation-states. Rulers will almost always seek to preserve their own power, even if this entails committing serious injustices against innocent people, both domestic and foreign, through aggressive and predatory wars. Rulers will usually follow the dictates of prudence—where “prudence” means actions that will advance the interests of the rulers themselves—rather than respect the universal laws of justice, as demanded by the Categorical Imperative.

Meanwhile, rulers will contemptuously dismiss those philosophers who argue that the principles of justice should be upheld in the arena of international relationships. In the first paragraph of “Perpetual Peace” Kant made the following observation:

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.  (“Perpetual Peace,” trans. Lewis Beck, in On History, ed. Lewis Beck, Bobbs-Merrill, 1963, p. 85.)

It would be an understatement to say that Kant did not subscribe to Plato’s doctrine of the philosopher-king. A typical ruler, corrupted by his desire to preserve and enhance his exercise of power, will never agree to have his judgment in matters of war overridden either by his own people or by other states. Ideally, a republican form of government is best suited to maintain peace. When the powers of government are separated into three branches—legislative, executive, and judicial—and when the supreme authority, the legislative branch, is elected by the people, then only this popular assembly will have the power to declare war. (It should be noted that Kant did not favor universal suffrage.) As Kant explained in “Perpetual Peace” (pp. 94-95):

If the consent of the citizens is required in order to decide that war should be declared (and in this [republican] 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.

In contrast, in nonrepublican forms of government in which the executive is vested with the power to declare war, the temptation will be much greater than we find in republican governments. Indeed,

it is the easiest thing in the world to decide upon, because war does not require of the ruler…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 (p. 95).

Kant stressed that we should not confuse a republican form of government with democracy. In a democracy the people would ultimately control all three branches of government, and this would destroy the purpose of the separation of powers—a system designed so that the legislative branch can curtail the excesses of the executive branch. In a democracy there can be no effective checks on the abuse of power.

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 (p. 96).

According to Kant, governments are morally obligated to pursue peace. Here he drew a parallel between the proper domestic functions of governments and their international responsibilities. Like Grotius, Pufendorf and virtually every other just-war philosopher who preceded him, Kant viewed sovereign states as “moral persons” who exist in a state of nature vis-à-vis other states. As with humans who exist in a state of nature without a sovereign power to adjudicate disputes and enforce its decisions, a state of war will effectively exist among states. By a “state of war” Kant did not mean continuous violent conflict but rather the continuous threat of such conflict. Each state will naturally fear other states, and this fear will often result in war. This condition will continue so long as there exists no international mechanism to adjudicate disagreements among states, so Kant called for a federation of states (one that would ideally include every state in the world) vested with the authority to resolve conflicts among sovereign states.

We should understand that Kant did not favor a world-state. He rejected this idea because differences in language, culture, traditions, and so forth rendered a world-state thoroughly impracticable.  Nevertheless, a league of nations—or a “league of peace,” as Kant described it—should be charged with maintaining perpetual peace. This is a moral imperative, for the same reason that governments are necessary to preserve domestic peace. A state of war will exist, whether nationally or internationally, until and unless individual moral persons, including sovereign states, submit to the binding resolutions of an overarching authority.

One of these days I hope to write a series on the theory of war. If I manage to follow through on this plan, I will criticize in detail the notion that we should view states as moral persons, analogous to morally autonomous human beings existing in a state of nature. For now I will merely note my strong disagreement with this pernicious idea. Although many just-war philosophers, including Kant, had liberal tendencies and were motivated by a sincere desire to lessen the pretexts for war and to diminish its horrors, their treatment of states as sovereign moral entities generated enormous problems from a libertarian perspective. As Kant himself noted, rulers frequently cited Grotius, Pufendorf, and other just-war philosophers to justify their decisions to wage war, but rarely if ever were these philosophers cited to justify abstaining from war. 

Although perpetual peace was a moral ideal for Kant, he did not regard it as an unattainable goal. Rather, in the same manner that he defended the inevitability of progress in general (see my last essay), so he regarded perpetual peace as something that would eventually come about. But as with all progress, perpetual peace would take a long time to develop, and much of it would be the unintended consequence of human action—the result of self-interested behavior that does not have international peace as its immediate purpose. Like many classical liberals, for example, Kant invoked international free trade as a self-interested activity that, over time, will teach people the inestimable economic benefits of peaceful cooperation over war. Nations are less likely to wage war against other nations if those nations are mutually dependent on each other for essential goods and services. International trade, though pursued for personal gain, has the unintended consequence of lessening the incentives for war. Here is how Kant put the matter in “Perpetual Peace”:

The spirit of trade cannot coexist with war, and sooner or later this spirit dominates every people. For among all those powers (or means) that belong to a nation, financial power may be the most reliable in forcing nations to pursue the noble cause of peace (though not from moral motives); and wherever in the world war threatens to break out, they will try to head it off through mediation, just as if they were permanently leagued for this purpose.

Kant also proposed specific reforms that he thought would make war less likely. Two of these proposals are of particular interest to libertarians, because they link Kant to the ideas of Radical Whiggism in Britain and to the beliefs of many American revolutionaries.

First, Kant called for the gradual abolition of standing armies (professional armies maintained in peacetime) and for their replacement by citizen militias.

[Standing armies] incessantly menace other states by their readiness to appear at all times prepared for war; they incite them to compete with each other in the number of armed men, and there is no limit to this. For this reason, the cost of peace finally becomes more oppressive than that of a short war, and consequently a standing army is itself a cause of offensive war waged in order to relieve the state of this burden. Add to this that to pay men to kill or to be killed seems to entail using them as mere machines and tools in the hand of another (the state), and this is hardly compatible with the rights of mankind in our own person (p. 87).

Second, although Kant did not oppose the accumulation of a national debt for domestic purposes, he resolutely opposed a national debt when the money was used for military purposes. Here he specifically had in mind the English system of financing wars—the “financial revolution” that began with the establishment, in 1694, of the Bank of England. This quasi-private bank was criticized by Adam Smith and many other free-market types as a hazardous alliance between private and governmental institutions, one that would encourage the waging of war on credit (through a national debt) without the need to pay the costs as the war proceeded. Money had long been viewed as the “sinews of war”; and the tremendous expense of waging war, which threatened to hurl warring governments into bankruptcy, tended to place a natural limit on how long wars could continue, as well as make rulers think twice before engaging in war. But this financial check had been largely eliminated with the advent of the English financial system; and Kant, in league with many classical liberals, warned against the danger.

[A] credit system which grows beyond sight and which is yet a safe debt for the present requirement—because all the creditors do not require payment at one time—constitutes a dangerous money power. This ingenious invention of a commercial people [England] in this century is dangerous because it is a war treasure which exceeds the treasures of all other states; it cannot be exhausted except by default of taxes [payment of perpetual interest to investors was tied to future taxes] (which is inevitable), though it can be long delayed by stimulus to trade which occurs through the reaction of credit on industry and commerce. This facility in making war, together with the inclination to do so on the part of rulers—an inclination which seems inborn in human nature—is thus a great hindrance to perpetual peace (p. 88).

My series on Immanuel Kant is now concluded. I did not originally plan to write this series. Rather, I interrupted my series on John Locke to write three contributions for Libertarianism.org’s “Fascism Month.” And that got me into Ayn Rand’s claim that Kant was a forerunner of fascistic ideology, and her notorious allegation that Kant was “the most evil man in mankind’s history.” For those willing to read my 13 essays in this series on Kant, the absurdity of both charges should be abundantly obvious.