All natural capacities of a creature are destined to evolve completely to their natural end. In man (as the only rational creature on earth) those natural capacities which are directed to the use of his reason are to be fully developed only in the race, not in the individual.
It remains strange that the earlier generations appear to carry through their toilsome labor only for the sake of the later, to prepare for them a foundation on which the later generations could erect the higher edifice which was Nature’s goal, and yet that only the latest of the generations should have the good fortune to inhabit the building on which a long line of their ancestors had (unintentionally) labored without being permitted to partake of the fortune they had prepared. However puzzling this may be, it is necessary if one assumes that a species of animals should have reason, and, as a class of rational beings each of whom dies while the species is immortal, should develop their capacities to perfection.
The means employed by Nature to bring about the development of all the capacities of men is their antagonism in society, so far as this is, in the end, the cause of a lawful order among men. By “antagonism” I mean the unsocial sociability of men, i.e., their propensity to enter into society, bound together with a mutual opposition which constantly threatens to break up the society. Man has an inclination to associate with others, because in society he feels himself to be more than man, i.e., as more than the developed form of his natural capacities.
The greatest problem for the human race, to the solution of which Nature drives man, is the achievement of a universal civic society which administers law among men. The highest purpose of Nature, which is the development of all the capacities which can be achieved by mankind, is attainable only in society, and more specifically in the society with the greatest freedom. Such a society is one in which there is mutual opposition among the members, together with the most exact definition of freedom and fixing of its limits so that it may be consistent with the freedom of others. (…) The same unsociability which drives man to this causes any single commonwealth to stand in unrestricted freedom in relation to others; consequently, each of them must expect from another precisely the evil which oppressed the individuals and forced them to enter into a lawful civic state. The friction among men, the inevitable antagonism, which is a mark of even the largest societies and political bodies, is used by Nature as a means to establish a condition of quiet and security. Through war, through the taxing and never-ending accumulation of armament, through the want which any state, even in peacetime, must suffer internally, Nature forces them to make at first inadequate and tentative attempts; finally, after devastations, revolutions, and even complete exhaustion, she brings them to that which reason could have told them at the beginning and with far less sad experience, to wit, to step from the lawless condition of savages into a league of nations. In a league of nations, even the smallest state could expect security and justice, not from its own power and by its own decrees, but only from this great league of nations (Foedus Amphictyonum), from a united power acting according to decisions reached under the laws of their united will.
The history of mankind can be seen, in the large, as the realization of Nature’s secret plan to bring forth a perfectly constituted state as the only condition in which the capacities of mankind can be fully developed, and also bring forth that external relation among states which is perfectly adequate to this end. This is a corollary to the preceding. Everyone can see that philosophy can have her belief in a millennium, but her millennarianism is not Utopian, since the Idea can help, though only from afar, to bring the millennium to pass. The only question is: Does Nature reveal anything of a path to this end? And I say: She reveals something, but very little. This great revolution seems to require so long for its completion that the short period during which humanity has been following this course permits us to determine its path and the relation of the parts to the whole with as little certainty as we can determine, from all previous astronomical observation, the path of the sun and his host of satellites among the fixed stars. Yet, on the fundamental premise of the systematic structure of the cosmos and from the little that has been observed, we can confidently infer the reality of such a revolution.
A philosophical attempt to work out a universal history according to a natural plan directed to achieving the civic union of the human race must be regarded as possible and, indeed, as contributing to this end of Nature. It is strange and apparently silly to wish to write a history in accordance with an Idea of how the course of the world must be if it is to lead to certain rational ends. It seems that with such an Idea only a romance could be written. Nevertheless, if one may assume that Nature, even in the play of human freedom, works not without plan or purpose, this Idea could still be of use. Even if we are too blind to see the secret mechanism of its workings, this Idea may still serve as a guiding thread for presenting as a system, at least in broad outlines, what would otherwise be a planless conglomeration of human actions. (…) It can serve not only for clarifying the confused play of things human, and not only for the art of prophesying later political changes (a use which has already been made of history even when seen as the disconnected effect of lawless freedom), but for giving a consoling view of the future (which could not be reasonably hoped for without the presupposition of a natural plan) in which there will be exhibited in the distance how the human race finally achieves the condition in which all the seeds planted in it by Nature can fully develop and in which the destiny of the race can be fulfilled here on earth.
Such a justification of Nature – or, better, of Providence – is no unimportant reason for choosing a standpoint toward world history. For what is the good of esteeming the majesty and wisdom of Creation in the realm of brute nature and of recommending that we contemplate it, if that part of the great stage of supreme wisdom which contains the purpose of all the others – the history of mankind – must remain an unceasing reproach to it? If we are forced to turn our eyes from it in disgust, doubting that we can ever find a perfectly rational purpose in it and hoping for that only in another world?
Kant, Idea for a Universal History from a Cosmopolitan Point of View (1784).