Most of the key words commonly used to describe governments, words such as monarchy, oligarchy, and democracy, are of Greek or Roman origin. They have been current for more than 2,000 years and have not yet exhausted their usefulness. This suggests that humankind has not altered very much since they were coined; however, such verbal and psychological uniformity must not be allowed to hide the enormous changes in society and politics that have occurred. The earliest analytical use of the term monarchy occurred in ancient Athens, in the dialogues of Plato (c. 428–c. 348 BC), but even in Plato's time the term was not self-explanatory. There was a king in Macedonia and a king in Persia, but the two societies, and therefore their institutions, were radically different. To give real meaning to the word monarchy in those two instances, it would be necessary to investigate their actual political and historical contexts. Any general account of monarchy required then, and requires today, an inquiry as to what circumstances have predisposed societies to adopt monarchy and what have led them to reject it. So it is with all political terms.

The city-state was made possible by Mediterranean geography, which is such that every little fishing village had to be able to defend itself against attack from land or sea, for outside help could not reach it easily. A person's dependence on his community, for physical as well as economic survival, was therefore obvious and complete. The city had first claim on his labour and loyalty, a claim that was usually freely recognized. It was this reality that led Aristotle (who himself came from just such a small commonwealth, Stageira) to define man as a political animal. In addition, coastal mountain ranges made it difficult for any community in Greece to dominate more than a few square miles of land. Therefore, in the Greek world (which by c. 600 BC stretched from the coasts of Asia Minor to what is now southern France), there were dozens of centres of government. The term city-state expresses the double aspect of those small settlements.

For to the north of Hellas proper, a new power arose. Greek civilization had slowly trained and tamed the wild men of Macedonia. Their king, Philip II, forged them into a powerful army; he and his son Alexander the Great then seized the opportunity open to them. History and geography made it impossible for the Greek cities to hang together, so they were hanged separately. It seemed as if the city-state had been but a transient expedient. Henceforward Athens and Sparta would take their orders from foreign conquerors—first Macedonia, then Rome.

Polybius was right: power in Rome was indeed shared among the people, the aristocracy (embodied in the Senate), and the consuls (consul)—the executive officers of the republic who had replaced the kings. The claims of the many and the few were fought out at election time, when the world's first clearly identifiable political parties appeared. Until the republic's decline, the results of elections were universally respected, and the triumphant alliance of the few and the many against the world was proclaimed in the letters blazoned on the city's buildings and battle standards: “SPQR,” for Senatus populusque Romanus (“The Senate and the people of Rome”).

The bedrock of the emperor Augustus's power was his command of the legions with which he had defeated all his rivals, but he was a much better politician than he was a general, and he knew that naked political power is as insecure as it is expensive. He reduced the military establishment as much as was prudent, laboured to turn the revolutionary faction that had supported his bid for power into a respectable new ruling class, and proclaimed the restoration of the republic in 27 BC. But not even Augustus could make the restoration real. The safety of the state, questions of war and peace, and most of the business of governing the empire were now in the hands of a monarch; consequently, there was not enough for the Senate to do, and Augustus never went so far as to restore genuinely free elections or the organs of popular government. He kept the population of the city happy with chariot races, gladiatorial contests, and the dole of bread. Nevertheless, he could not give up the attempt to legitimize his regime. Like earlier monarchs elsewhere, he called in the aid of religion, even though the religion of Rome was as republican as its constitution. Later emperors made their own divinity a tenet of the public faith; later still, they imposed Christianity as the sole legitimate and official religion of the empire, and they exploited the power and prestige of the church to buttress their own authority.

The Europeans failed to emulate that story. Justinian I, the greatest of the Eastern Roman (Byzantine) emperors, reconquered large portions of the West in the 6th century, though the destruction wreaked by his soldiers made things worse rather than better. In 800 Charlemagne, king of the Franks, was actually crowned emperor of the Romans by the pope. In later centuries the Hohenstaufen (Hohenstaufen dynasty) and Habsburg (Habsburg, House of) dynasties tried to restore the empire; as late as the 19th century, so did Napoleon I. None of those attempts succeeded. Probably the chance was only real in the earliest period, before western Europe had become used to doing without an overlord. But at that time there was never enough breathing space for society to regain its stability and strength. Most of the barbarian kingdoms, successor states to Rome, succumbed to later assailants. Britain fell away from the empire in the 5th century; the little kingdoms of the Angles and Saxons were just coming together as one kingdom, England, when the Viking invasions began. In the 7th century the Arabs conquered North Africa; in the 8th they took Spain and invaded Gaul. Lombards, Avars, Slavs, Bulgars, and Magyars poured into Europe from the East. Not until German king Otto I's victory over the Magyars at Lechfeld in 955 did those incursions cease, and not until the late 11th century was Latin Christendom more or less secure within its borders; and by then it had been without an effective emperor for more than 600 years.

Medieval Europe, in fact, was a constantly shifting kaleidoscope of political arrangements; to the extent that it ever settled down, it did so on the principle that because everybody's claim to power and property was fragile and inconsistent with everybody else's, a certain degree of mutual forbearance was necessary. This explains the great importance attached to custom, or (as it was called in England) common law. Disputes were still often settled by force, especially when kings were the disputants, but the medieval European became almost as fond of law as of battle. Every great estate was hung about with quasi-permanent lawsuits over ownership of land and the rights and privileges that went with it, and the centralization of the church on the papal court at Rome ensured yet more work for lawyers, the greatest of whom began to merge with the military nobility into an aristocracy of a new kind. Rights, titles, and privileges were forever being granted, revoked, and reaffirmed. Parchment deeds (of which Magna Carta, exacted from King John of England by his subjects in 1215, was perhaps the most famous) came to regulate political, social, and economic relationships at least as much as the sword did. In those ways the idea of the rule of law was reborn. By the beginning of the early modern period legally demonstrable privileges had become the universal cement of European society. The weak were thus enabled to survive alongside the strong, as everyone in Europe knew to which order of society he belonged.

The rise in power of Henry VIII and other early modern kings may be attributed in part to the use of gunpowder, which had enabled the kings to overbear their turbulent nobles—cannons were extremely effective at demolishing the castles in which rebellious barons had formerly been quite safe. But artillery was exceedingly expensive. A sufficient revenue had always been one of the chief necessities of monarchy, but none of the great European kingdoms, in their autocratic phase, ever succeeded in securing one permanently. The complexities of medieval society had permitted very little coercion of taxpayers. For the rest, money could only be secured by chicanery; by selling offices or crown lands (at the price of a long-term weakening of the monarch); by robbing the church; by a lucky chance, such as the acquisition of the gold and silver of Mexico and Peru by the king of Spain; or by dealing, on a semi-equal footing, with parliaments (or estates, as they were most generally known).

But by then the inadequacies of the monarchical system had been cruelly exposed in such episodes as the revolt of the Netherlands against its Spanish overlord, the defeat of Spain's Invincible Armada by England, and, worst of all, the snail's-pace development of the Spanish colonies in the New World. The Spanish king Charles V and his son Philip II were as able as all but a few monarchs in recorded history, but they could not overcome the structural weaknesses of hereditary monarchy. There was no mechanism by which they could devolve their most crushing duties onto their ministers, so government moved slowly, if at all. As lawful sovereigns they were bound by the customs of their numerous realms, which frequently blocked necessary measures but could not safely be challenged, as Philip found when he tried to rule the Netherlands autocratically. They also were unable to guarantee that their heirs would be their equals in ability. The only remedy discoverable within the system was for the king in effect to abdicate in favour of a chief minister. Unfortunately, a man equal to the task was seldom found, and no minister, however gifted, was ever safe from the constant intrigues and conspiracies of disgruntled courtiers. Problems tended to accumulate until they became unmanageable. The same difficulties eventually ruined the French monarchy as well.

The limited British monarchy found it little easier to govern a seaborne empire than did the kings of France and Spain. If Britain's North American colonies were to grow in population and riches—so as to become sources of strength to the empire, not military and financial liabilities—they had to be given a substantial measure of religious, economic, and political autonomy. However, that gift could not be revoked. Once British policy had created a chain of more or less self-governing communities along the Atlantic seaboard—communities much like the city-states of old—it could not undo its own work, even when it found its clients unreasonable, small-minded, and recalcitrant. Thus, when the British government attempted to impose tighter rule from London, the old empire broke down in bickering about taxation and in rioting, rebellion, and civil war—in short, the American Revolution. From 1775 to 1783 the Anglo-Americans fought with determination and good luck against their former overlord, King George III, and in 1776 their leaders determined to be rid of him and the British Parliament forever. The principles on which they meant to found a new commonwealth were expounded in their Declaration of Independence:We hold these truths to be self-evident, that all men are created equal, that they are endowed by their Creator with certain inalienable Rights, that among these are Life, Liberty and the pursuit of Happiness. That, to secure these rights, Governments are instituted among Men, deriving their just powers from the consent of the governed . . . .

The application of those principles was more difficult than their enunciation, and it took the Americans more than a decade to create a suitable framework of government. When they did adopt a new constitution, it served them so well that it is still in operation. That durability is not unconnected with the fact that the Constitution of the United States of America opened the door to modern liberal democracy—democracy in which the liberty of the individual is paramount (see liberalism). “The consent of the governed” was agreed to be the key to governmental legitimacy, and in practice the phrase rapidly came to mean “the consent of the majority.” The principle of representation was embodied in the U.S. Constitution (the first section of which was entirely devoted to the establishment of Congress (Congress of the United States), the American parliament); this implied that there was no necessary limit to the size of a successful republic. From Plato to Jean-Jacques Rousseau (Rousseau, Jean-Jacques), theorists had agreed that democracies had to be small, because by definition all their citizens had to be able to give their consent in person. Now that notion had been discarded.

The American example might have had little effect on Europe but for the French Revolution of 1789. The French (France) had helped the Americans defeat the British, but the effort had been too much in the end for the monarchy's finances. To avert state bankruptcy the Estates-General were summoned for the first time in 175 years, and soon the whole government had been turned upside down. The French repudiated the divine right of kings, the ascendancy of the nobility, the privileges of the Roman Catholic Church, and the regional structure of old France. Finally, they set up a republic and cut off the king's head.

nationalism intensified the competitiveness that had always been a part of the European state system. Peoples, it emerged, could be as touchy about their prestige as monarchs. But for one hundred years there was no general war in Europe, leaving the powers free to pursue interests in other parts of the world. Asia and Africa thus came to feel the full impact of European expansion (imperialism), as the Americas had felt it before. Only the Japanese proved to have the skill to adapt successfully to the new ways—taking what suited them and rejecting the rest. They kept their millennial sacred monarchy but modernized the armed forces. In 1895 they fought and won a war against China, which was sliding into chaos, and in 1905 they defeated a great power, Russia. However, Japan was wholly exceptional. Elsewhere, European power was irresistible. Britain gave up the attempt to govern overseas settlements (colonialism, Western) of its own people directly—the experiment had proved fatal in America and nearly so in Canada—but it had no scruple about wielding direct rule over non-British peoples, above all in India. France, Germany, and the United States eagerly followed this example; The Netherlands, Spain, and Portugal clung to what they had, though the last two suffered great imperial losses as Mexico, Brazil, and other Latin American colonies shook off imperial rule. It seemed that before long the whole world would be ruled by half a dozen powers. (See imperialism; colonialism, Western.)

It did not turn out so, or not for long. The problem of governmental legitimacy in central, eastern, and southern Europe was too explosive. The obstinate conservatism of the dynasts proved fatal to more than monarchy. There were too many who regarded the dynastic states as unacceptable, either because they were the instruments of class oppression, or because they embodied foreign rule, or both. And the romantic tradition of the French Revolution—the fall of the Bastille, the Reign of Terror, the Jacobin dictatorship—helped to drive many of those critics into violent rebellion, permanent conspiracy, and corrosive cynicism about the claims of authority. Authority itself, corrupted by power and at the same time gnawingly aware of its own fragility, gambled on militarist adventures. The upshot was World War I and the revolutions that resulted from it, especially those in Russia in March and November 1917, which overthrew the tsardom and set up a new model of government. (See Russian Revolution of 1917.)

Vladimir Ilich Lenin (Lenin, Vladimir Ilich) and his followers, the Bolsheviks (Bolshevik) (later known as the Communist Party of the Soviet Union), won power in the turmoil of revolutionary Russia because they were abler and more unscrupulous than any other group. They retained and increased their power by force, but they argued that the theories (Leninism) of Karl Marx (Marx, Karl) (1818–83), as developed by Lenin, were of universal, permanent, and all-sufficient validity, that the leadership of the Communist (communism) Party had a unique understanding of those theories and of the proper tactics for realizing them, and that therefore the party's will could never legitimately be resisted. All institutions of the Soviet state were designed primarily to assure the untrammeled power of the party, and no methods were spurned—from mass starvation to the murder of artists—in furtherance of that aim. Even the economic and military achievements of the regime were secondary to that overall purpose; its most characteristic institutions, after the party, were the secret police and the forced labour camps. (See communism, Leninism).

The Soviet model found many imitators. Lenin's strictly disciplined revolutionary party, the only morality of which was unswerving obedience to the leader, was a particularly attractive example to those intent on seizing power in a world made chaotic by World War I. Benito Mussolini (Mussolini, Benito) of Italy, who won power in 1922, modeled his National Fascist Party on the Leninists, but he also exploited Italian traditions (including that of Garibaldi) in his portrayal of himself as a heroic leader. The ideology he manufactured to justify his regime, fascism, combined strident nationalism with unrelenting bellicosity. Adolf Hitler (Hitler, Adolf) of Germany added a vicious anti-Semitism and a lust for mass murder to that brew. Mao Zedong in China combined Leninism with a hatred of all the foreign imperialists who had reduced China to nullity. In the Soviet Union itself Lenin's successor and disciple, Joseph Stalin (Stalin, Joseph), outdid his master in building up his power (Stalinism) by mass terror and party discipline (see Stalinism). Fascist practices were to some extent adopted by the government of Japan, the Nationalist victors in the Spanish Civil War (1936–39), and others. All in all, the post-World War I period was characterized by state criminality on an unprecedented scale. It unsurprisingly culminated in World War II, which was marked by even greater atrocities, of which Hitler's murder of six million Jews and millions of others in the Holocaust was the worst.

Meanwhile, liberal democracy had gotten its second wind. Although the democracies had failed to avert the world wars and the Great Depression, they crushed the Axis powers in World War II and warded off the rivalry of communism in the Cold War that followed. Those achievements were undoubtedly in large part attributable to the colossal strength of the United States, but that strength itself was largely created by the American system of government, especially in the hands of President Franklin D. Roosevelt (Roosevelt, Franklin D.). American success scarcely faltered when Roosevelt suddenly died in 1945: by the end of the 20th century the country was generally looked on as the world's only superpower. Yet the parallel success of many other democracies—and the fact that the American model could not really be exported, being closely adapted to specific American conditions—showed that there was more to the triumph of the West than Americanism.

In a world increasingly knit together by trade and communications technology, it seems ever more unlikely that the single nation-state can on its own successfully handle the universal enemies of poverty, hunger, disease, natural disaster, and war or other violence. Some thinkers believe that only a form of world government can make decisive headway against those evils, but no one has yet suggested convincingly either how a world government could be set up without another world war or how, if such a government did somehow come peacefully into existence, it could be organized so as to be worthy of its name. Even effective global cooperation among national governments can be extremely difficult, as the examples of the United Nations and other international bodies have shown. Nevertheless, those bodies have had many accomplishments, and the European Union (EU) has been particularly successful. The EU began as an attempt to bury the long-standing rivalry between France and Germany through economic cooperation; by the early 21st century it had come to include almost all the states between the Russian frontier and the Atlantic Ocean. Though its overall constitutional structure remained weak, and agreement on how to sufficiently strengthen it seemed unattainable, the EU's common laws and policies were playing a large part in the lives of its citizens.

Classic texts on governmental forms are widely available in numerous editions. They include Plato, The Republic; Aristotle, Politics; Niccolò Machiavelli, The Prince and The Discourses; Thomas Hobbes, Leviathan; John Locke, Two Treatises of Government; Montesquieu, The Spirit of Laws; Jean-Jacques Rousseau, The Social Contract; Thomas Jefferson, Declaration of Independence; Alexander Hamilton, James Madison, and John Jay, The Federalist; Edmund Burke, Reflections on the Revolution in France; Thomas Paine, Rights of Man; Alexis de Tocqueville, Democracy in America; Walter Bagehot, The English Constitution; James Bryce, The American Commonwealth; Friedrich Engels, The Origin of the Family, Private Property, and the State; and Vladimir Ilich Lenin, The State and Revolution.For a subject of this nature, a solid background in world history is absolutely necessary, and William H. McNeill, A World History, 4th ed. (1999), is an excellent introduction. Gordon Childe, What Happened in History, rev. ed. (1954, reissued 1982), is a classic survey of the contribution of archaeology to our understanding of prehistory and the ancient world. The development of governmental forms in Greece can be found in The Cambridge Ancient History, 3rd ed. (1970–); and in N.G.L. Hammond, A History of Greece to 322 B.C., 3rd ed. (1986). A.H.M. Jones, Athenian Democracy (1957, reissued 1986), has a corrective to Plato, Aristotle, and Thucydides. The most exciting work about the Romans since Gibbon is Ronald Syme, The Roman Revolution (1939, reissued 1987). Those wanting more general accounts of the Romans may turn to J.P.V.D. Balsdon (ed.), The Romans (1965); and H.H. Scullard, From the Gracchi to Nero: A History of Rome from 133 B.C. to A.D. 68, 5th ed. (1982, reprinted 1992). A.H.M. Jones, The Later Roman Empire, 284–602: A Social, Economic, and Administrative Survey, 2 vol. (1964, reprinted 1986), is the most authoritative account of the fall of the empire.The best introduction to the medieval papacy is Walter Ullmann, A Short History of the Papacy in the Middle Ages (1972, reprinted with corrections, 1974), while The Growth of Papal Government in the Middle Ages: A Study in the Ideological Relation of Clerical to Lay Power, 3rd ed. (1970), links ideas and institutions but makes few concessions to beginners. Marc Bloch, Feudal Society (1961, reprinted 1989; originally published in French, 1939), is an indispensable study of its subject.The development of political thought from the Renaissance to the 19th century is well presented in John Plamenatz, Man and Society: Political and Social Theories from Machiavelli to Marx, new 2nd ed., rev. by M.E. Plamenatz and Robert Wokler, 3 vol. (1992). An attempt to trace modern government back to its origins is demonstrated in Barrington Moore, Jr., Social Origins of Dictatorship and Democracy: Lord and Peasant in the Making of the Modern World (1966, reissued 1993). Further information is available in Perry Anderson, Lineages of the Absolutist State (1974); and Franco Venturi, Utopia and Reform in the Enlightenment (1970; originally published in Italian, 1970).Works on governmental forms of a general, comparative nature include Albert Goodwin (ed.), The European Nobility in the Eighteenth Century: Studies of the Nobilities of the Major European States in the Pre-Reform Era, 2nd ed. (1967); A. Lawrence Lowell, Governments and Parties in Continental Europe, 2 vol. (1896, reissued 1970); Eugene N. Anderson and Pauline R. Anderson, Political Institutions and Social Change in Continental Europe in the Nineteenth Century (1967); Michael Oakeshott, The Social and Political Doctrines of Contemporary Europe (1939, reissued 1953); and S.E. Finer, Comparative Government (1970, reissued 1980).Useful studies of English government include J.H. Plumb, The Origins of Political Stability, England, 1675–1725 (1965; also published as The Growth of Political Stability in England, 1675–1725, 1967, reissued 1980); and Elie Halevy, A History of the English People in the Nineteenth Century, 2nd rev. ed., 6 vol. in 7, trans. from French (1949–52). The French experience is dealt with in C.B.A. Behrens, The Ancien Régime (1967, reissued 1989); Georges Lefebvre, The French Revolution, 2 vol. (1962–64; originally published in French, 1930); and D.W. Brogan, The French Nation from Napoleon to Pétain, 1814–1940 (1957, reissued 1989). Prussia and the development of fascist Germany are discussed in Hans Rosenberg, Bureaucracy, Aristocracy, and Autocracy: The Prussian Experience, 1660–1815 (1958, reissued 1968); A.J. Nicholls, Weimar and the Rise of Hitler, 4th ed. (2000); Franz Neumann, Behemoth: The Structure and Practice of National Socialism, 1933–1944, 2nd ed. (1944, reissued 1983); and Martin Broszat, The Hitler State: The Foundation and Development of the Internal Structure of the Third Reich (1981; originally published in German, 1969). Sources on Italy include Denis Mack Smith, Italy: A Modern History, new ed. rev. and enlarged (1969); and S.J. Woolf (ed.), The Nature of Fascism (1968). Jerome Blum, Lord and Peasant in Russia: From the Ninth to the Nineteenth Century (1961, reissued 1971); Leonard Schapiro, The Origin of the Communist Autocracy: Political Opposition in the Soviet State, First Phase, 1917–1922, 2nd ed. (1977, reprinted 1987); and Ronald Grigor Suny, The Soviet Experiment: Russia, the U.S.S.R., and the Successor States (1998), deal with Russia and the Soviet Union. Coverage of the United States is in Richard Hofstadter, The American Political Tradition and the Men Who Made It (1948, reissued 1996); Alfred H. Kelly, Winfred A. Harbison, and Herman Belz, The American Constitution: Its Origins and Development, 7th ed., 2 vol. (1991); and Melvyn Dubofsky and Athan Theoharis, Imperial Democracy: The United States Since 1945 (1988). The governing structure of the European Union is discussed in Desmond Dinan, Ever Closer Union: An Introduction to European Integration, 3rd ed. (2005).Hugh Brogan