Future
In 1945, historian Ludwig Dehio predicted global unification due to the circumscription of the global system, although he did not use this term. Being global, the system can neither expand nor be subject to external intrusion as the European states system had been for centuries:
In all previous struggles for supremacy, attempts to unite the European peninsula in a single state have been condemned to failure primarily through the intrusion of new forces from outside the old Occident. The Occident was an open area. But the globe was not, and, for that very reason, ultimately destined to be unified... And this very process [of unification] was clearly reflected in both World Wars.
Fifteen years later, Dehio confirmed his hypothesis: The European system owed its durability to its overseas outlet. "But how can a multiple grouping of world states conceivably be supported from outside in the framework of a finite globe?"
During the same time, Quincy Wright developed a similar concept. Balance-of-power politics has aimed less at preserving peace than at preserving the independence of states and preventing the development of world empire. In the course of history, the balance of power repeatedly re-emerged, but on ever-wider scale. Eventually, the scale became global. Unless we proceed to "interplanetary wars," this pattern can no longer continue. In spite of significant reversals, the "trend towards world unity" can "scarcely be denied." World unity appears to be "the limit toward which the process of world history seems to tend."
The same "interplanetary" motif is present also in the Anatomy of Peace: The era of outward expansion is forever closed. "Until and unless we are able to communicate with another planet, the theater of human history will be limited to geographically determined, constant and known dimensions." The historic trend of expansion will result in direct collision between the remaining powers. Multiplied by modern technology, the centripetal forces will accomplish what the greatest empires of the past failed. "For the first time in human history, one power can conquer and rule the world."
The "Father of American Anthropology", Franz Boas, known for his historical particularism and cultural relativism, outlined the "inexorable laws of history" by which political units grow larger in size and smaller in number. The process began in the earliest times and has continued almost always in the same direction. In the long run, the tendency to unification has been more powerful than of disintegration. "Thus the history of mankind shows us the grand spectacle of the grouping of man in units of ever increasing size." The progress in the direction of unification has been so regular and so marked that we must needs conclude that the same tendencies will govern our history in the future. Today the unity of the world is not less conceivable than the modern nations were in the early history. The practical difficulties that stand in the way of the formation of still larger units count for nothing before the "inexorable laws of history."
Seven later scholars—Hornell Hart, Raoul Naroll, Louis Morano, Rein Taagepera, the author of the circumscription theory Robert Carneiro and Jesse H. Ausubel & Cesare Marchetti—quantitatively researched expanding imperial cycles. Initially, the imperiometric scholars worked with historical atlases but the advent of YouTube created a more dynamic visualization. Later spot-checks with Wikipedia showed few disagreements. All seven scholars concluded that imperial cycles represent an historical trend leading to world empire. Naroll and Carneiro found this outcome "close at hand," c. 2200 and 2300 respectively. In 2013, Marchetti and Ausubel estimated that the global empire is to rise within "a couple more generations." These predictions surprised their many contemporaries, as the 20th century has seen falls of empires, decolonization, and increase in the number of independent states. Nevertheless, the authors explained, when viewed within the millennial context, this recent reversal appears akin to random fluctuation. Since the dawn of history, the total number of separate polities has been reduced from thousands of tribes and states to about 200 and the number was even less in recent history. None of the authors is determinist: "The future is not obliged to continue past trends; it just often does..."
The reversal of the trend in 20th century those scholars stated, according to Max Ostrovsky, does not exist. Instead, the 20th century is the point when the historical atlases they worked with reverse their approach and begin painting every nominal sovereignty in different color. They had not done so for the earlier history. Most imperial provinces in history were nominally independent but historical atlases paint them all in the color of their metropole. Since the 20th century, however, political maps begin painting every Vatican, Monaco and Tuvalu in different color. None of the seven mentioned imperiometric scholars counted the sphere under the Monroe Doctrine, for example, or the sphere after the Monroe Doctrine was extended to Eurasia, named Truman Doctrine, and "globalized." To preserve the consistent approach, Ostrovsky says, in the 20th century we should switch from historical atlases to the map of the Unified Combatant Command.
Though unnoted by contemporary imperiometric scholars, the phenomenon reflected in the latter map was envisaged by the founder of the Paneuropean Union, Richard von Coudenhove-Kalergi yet in 1943, when he drew a specific and immediate future imperial project: After the War America is bound "to take over the command of the skies." The danger of "the utter annihilation of all enemy towns and lands" can "only be prevented by the air superiority of a single power ... America's air role is the only alternative to intercontinental wars." Despite his outstanding anti-imperialism, Coudenhove-Kalergi detailed:
No imperialism, but technical and strategic problems of security urge America to rule the skies of the globe, just as Britain during the last century ruled the seas of the world... Pacifists and anti-imperialists will be shocked by this logic. They will try to find an escape. But they will try in vain... At the end of the war the crushing superiority of American plane production will be an established fact... The solution of the problem ... is by no means ideal, nor even satisfactory. But it is the minor evil...
Coudenhove-Kalergi envisaged a kind of Pax Americana modeled on "Pax Romana":
During the third century BC the Mediterranean world was divided on five great powers—Roma and Carthage, Macedonia, Syria, and Egypt. The balance of power led to a series of wars until Rome emerged the queen of the Mediterranean and established an incomparable era of two centuries of peace and progress, the 'Pax Romana'... It may be that America's air power could again assure our world, now much smaller than the Mediterranean at that period, two hundred years of peace...
This period would be necessary transitory stage before World State is eventually established, though he did not specify how the last transformation is expected to occur. Coudenhove-Kalergi's follower in the teleological theory of World State, Toynbee, specified two ways. One is by wars going on to a bitter end at which one surviving great power "knocks out" its last remaining competitor and establishes world empire, like the earlier empires used to on the regional scale. The other alternative is the United Nations. Having devoted his life to the study of history and international affairs, Toynbee did not bet on the United Nations. Instead, he identified symptoms of the traditional power politics leading to the world empire by a universal conquest.
Toynbee emphasized that the world is ripe for conquest: "...Hitler's eventual failure to impose peace on the world by the force of arms was due, not to any flaw in his thesis that the world was ripe for conquest, but to an accidental combination of incidental errors in his measures..." But "in falling by so narrow a margin to win the prize of world-dominion for himself, Hitler had left the prize dangling within the reach of any successor capable of pursuing the same aims of world-conquest with a little more patience, prudence, and tact." With his "revolution of destruction," Hitler has performed the "yeoman service" for "some future architect of a Pax Ecumenica... For a post-Hitlerian empire-builder, Hitler's derelict legacy was a gift of the Gods."
The next "architect of a Pax Ecumenica", known more commonly as Pax Americana, demonstrated "more patience, prudence, and tact". Consequently, as President Dwight Eisenhower put it, the NATO allies became "almost psychopathic" whenever anyone talked about a US withdrawal, and the reception of his successor John F. Kennedy in Berlin was "almost hysterical," as Chancellor Konrad Adenauer characterized it. John Ikenberry finds that the Europeans wanted a stronger, more formal and more imperial system than the United States was initially willing to provide. In the end the United States settled for this "form of empire—a Pax Americana with formal commitments to Europe." According to a much debated thesis, the United States became "empire by invitation." The period discussed in the thesis (1945–1952) ended precisely the year Toynbee theorized on "some future architect of a Pax Ecumenica."
Dissociating America from Rome, Eisenhower gave a pessimistic forecast. In 1951, before he became president, he had written on West Europe: "We cannot be a modern Rome guarding the far frontiers with our legions if for no other reason than that these are not, politically, our frontiers. What we must do is to assist these [West European] peoples." Two years later, he wrote: When it was decided to deploy US divisions to Europe, no one had "for an instant" thought that they would remain there for "several decades"—that the United States could "build a sort of Roman Wall with its own troops and so protect the world."
Eisenhower assured Soviet first secretary Nikita Khrushchev on Berlin in 1959: "Clearly we did not contemplate 50 years in occupation there." It lasted, remarks Marc Trachtenberg, from July 1945 to September 1994, 10 months short of 50 years. Notably, when the US troops eventually left, they left eastward. Confirming the theory of the "empire by invitation," with their first opportunity East European states extended the "invitation."
Oswald Spengler envisaged the "Imperial Age" for the world in both senses of "empire," spatial (as a world-wide unit ruled by one center) and governmental (as ruled by Emperor). Published in 1922, The Decline of the West predicts the triumph of the strongest race in the fight for the whole world within "two generations" and of "Caesarism" over democracy "within a century." In 2022, the Spenglerian century ended short of global "Caesarism," albeit two years before its end Donald Trump had been advised to cross the Rubicon.
Chalmers Johnson regards the global military reach of the United States as empire in its "initial" form. For Charles H. Fairbanks, it is an empire "in formation" and for Kimberly Kagan an "emerging" empire. Dimitri Simes finds that most of the world sees the United States as a "nascent" imperial power. Some scholars concerned how this empire would look in its ultimate form. The ultimate form of empire was described by Michael Doyle in his Empires. It is empire in which its two main components—the ruling core and the ruled periphery—merged to form one integrated whole. At this stage the empire as defined ceases to exist and becomes world state. Doyle exemplifies the transformation on the case of the Roman Emperor Caracalla whose edict in AD 212 extended the Roman citizenship to all inhabitants of the Mediterranean world.
Doyle's case of the Roman Empire had also been evoked by Susan Strange in her 1988 article, "The Future of the American Empire." Strange emphasized that the most persistent empires were those which best managed to integrate the ruling core and the peripheral allies. The article is partly a reply on the published a year earlier bestseller The Rise and Fall of the Great Powers which predicted imminent US "imperial overstretch." Strange found this outcome unlikely, stressing the fact that the peripheral allies have been successfully recruited into the American Empire.
Envisaging a world empire of either the United States or the Soviet Union (whoever is victorious in World War III), Bertrand Russell projected the Roman scenario too: "Like the Romans, they will, in the course of time, extend citizenship to the vanquished. There will then be a true world state, and it will be possible to forget that it will have owed its origin to conquest." International Relations scholar Alexander Wendt supposes world empire by universal conquest and subsequent consolidation, provided the conquering power recognizes all conquered members. For his example he also invokes the Roman Empire. In satirical criticism of the European pro-American stance in the wake of September 11, French Philosopher Régis Debray warned that the logical culmination of the motto "We are all Americans" would be a modernized Edict of Caracalla extending US citizenship to all the West and thus establishing the United States of the West.
In the above views, the Edict of Caracalla is an advanced form of empire. Emmanuel Todd and Magdi Allam disregarded this nuance and compared the Edict with the US citizenship policy in the early 21st century. Todd found the US policy of this time lagging far behind the Roman under Caracalla while Allam stressed that the United States is also a nation forged by immigrants and already the most successful contemporary expression of multiculturalism the world has seen.
To the case of Caracalla, Toynbee added the Abbasid cosmopolitan reformation of 750 AD. Both "were good auguries for the prospect that, in a post-Modern chapter of Western history, a supranational commonwealth originally based on the hegemony of a paramount power over its satellites might eventually be put on the sounder basis of a constitutional partnership in which all the people of all the partner states would have their fare share in the conduct of common affairs." To the cases of Caracalla and the Abbasid revolution, Max Ostrovsky added the Han overthrow of Qin in 206 BC and more gradual cosmopolitan reformations he finds characteristic to all persistent empires and expects in the future global empire. The tragedy of empire is that it is disastrous for the conquered in the beginning and eventually for the conquerors, as they lose their privileges and often the very identity, becoming assimilated within the conquered population. Rein Taagepera called it imperial "self-ethnocide." When this distant stage comes to the American Empire, according to Ostrovsky, the green card is abolished since all Earth inhabitants have it by birth.
Crane Brinton expected that the world empire would not be built instantly but not as slowly as Rome, for much in the modern world has been speeded up. Charles Galton Darwin, a grandson of the father of Evolution Theory, suggested that China, as an isolated and enduring civilization, seems to provide the most relevant model for the global future. As the Chinese Empire, the regions of the world, periodically albeit more rarely, will be united by force into an uneasy world-empire, which will endure for a period until it falls. Along China, Ostrovsky mentions Egypt as a model for the future but, by contrast, estimates that the intermediate periods of the global empire will be shorter and rarer.