Polarity in
international relations
International relations (IR, and also referred to as international studies, international politics, or international affairs) is an academic discipline. In a broader sense, the study of IR, in addition to multilateral relations, concerns al ...
is any of the various ways in which
power is distributed within the international system. It describes the nature of the international system at any given period of time. One generally distinguishes three types of systems: unipolarity, bipolarity, and multipolarity for three or more centers of power. The type of system is completely dependent on the distribution of power and influence of
states
State most commonly refers to:
* State (polity), a centralized political organization that regulates law and society within a territory
**Sovereign state, a sovereign polity in international law, commonly referred to as a country
**Nation state, a ...
in a region or across the globe.
The
Cold War
The Cold War was a period of global Geopolitics, geopolitical rivalry between the United States (US) and the Soviet Union (USSR) and their respective allies, the capitalist Western Bloc and communist Eastern Bloc, which lasted from 1947 unt ...
period was widely understood as one of bipolarity with the
USA and the
USSR
The Union of Soviet Socialist Republics. (USSR), commonly known as the Soviet Union, was a List of former transcontinental countries#Since 1700, transcontinental country that spanned much of Eurasia from 1922 until Dissolution of the Soviet ...
as the world's two
superpowers
Superpower describes a sovereign state or supranational union that holds a dominant position characterized by the ability to exert influence and project power on a global scale. This is done through the combined means of economic, military, tec ...
, whereas the end of the Cold War led to unipolarity with the US as the world's sole superpower in the 1990s and 2000s. Scholars have debated how to characterize the current international system.
Political scientists
The following is a list of notable political scientists. Political science is the scientific study of politics, a social science dealing with systems of governance and power.
A
* Robert Abelson – Yale University psychologist and political ...
do not have an agreement on the question what kind of international politics polarity is likely to produce the most stable and peaceful system.
Kenneth Waltz
Kenneth Neal Waltz (; June 8, 1924 – May 12, 2013) was an American political scientist who was a member of the faculty at both the University of California, Berkeley, and Columbia University and one of the most prominent scholars in the field ...
and
John Mearsheimer
John Joseph Mearsheimer (; born December 14, 1947) is an American political scientist and international relations scholar. He is R. Wendell Harrison Distinguished Service Professor in the University of Chicago.
Mearsheimer is best known for dev ...
are among those who argue that bipolarity tends to produce a relatively high stability.
In contrast,
John Ikenberry and
William Wohlforth are among those arguing for the stabilizing impact of unipolarity.
Some scholars, such as
Karl Deutsch
Karl Wolfgang Deutsch (21 July 1912 – 1 November 1992) was a Czech social and political scientist. He was a professor at MIT, Yale University and Harvard University, as well as Director of WZB Berlin Social Science Center.
Deutsch studied war ...
and
J. David Singer, argued that multipolarity was the most stable structure.
Bruce Bueno de Mesquita has argued that the correlation between polarity of any kind and conflict is statistically weak, and depends critically on systemic uncertainty and risk attitudes among individual actors.
Unipolarity
Unipolarity is a condition in which one state under the condition of international anarchy enjoys a preponderance of power and faces no competitor states.
According to William Wohlforth, "a unipolar system is one in which a counterbalance is impossible. When a counterbalance becomes possible, the system is not unipolar."
A unipolar state is not the same as an
empire
An empire is a political unit made up of several territories, military outpost (military), outposts, and peoples, "usually created by conquest, and divided between a hegemony, dominant center and subordinate peripheries". The center of the ...
or a hegemon that can control the behavior of all other states.
American primacy
Numerous thinkers predicted U.S. primacy in the 20th century onwards, including
William Gladstone
William Ewart Gladstone ( ; 29 December 1809 – 19 May 1898) was a British politican, starting as Conservative MP for Newark and later becoming the leader of the Liberal Party.
In a career lasting over 60 years, he was Prime Minister ...
,
Michel Chevalier
Michel Chevalier (; 13 January 1806 – 18 November 1879) was a French engineer, statesman, economist and free market liberal.
Biography
Born in Limoges, Haute-Vienne, Chevalier studied at the ''École Polytechnique'', obtaining an engineering ...
,
Kang Youwei
Kang Youwei (; Cantonese: ''Hōng Yáuh-wàih''; 19March 185831March 1927) was a political thinker and reformer in China of the late Qing dynasty. His increasing closeness to and influence over the young Guangxu Emperor sparked confli ...
,
Kang Youwei
Kang Youwei (; Cantonese: ''Hōng Yáuh-wàih''; 19March 185831March 1927) was a political thinker and reformer in China of the late Qing dynasty. His increasing closeness to and influence over the young Guangxu Emperor sparked confli ...
, (1885): ''The One World Philosophy'', (tr. Thompson, Lawrence G., London, 1958, pp. 79-85). Georges Vacher de Lapouge,
[ Georges Vacher de Lapouge, ''L`Aryen: Son Role Social'', (Nantes, 1899: chapter "L`Avenir des Aryens," pp. XXXI-XXXII).] H. G. Wells
Herbert George Wells (21 September 1866 – 13 August 1946) was an English writer, prolific in many genres. He wrote more than fifty novels and dozens of short stories. His non-fiction output included works of social commentary, politics, hist ...
in ''
Anticipations'' (1900), and
William Thomas Stead
William Thomas Stead (5 July 184915 April 1912) was an English newspaper editor who, as a pioneer of investigative journalism, became a controversial figure of the Victorian era. Stead published a series of hugely influential campaigns whilst e ...
.
Liberal institutionalist
John Ikenberry argues in a series of influential writings that the United States purposely set up an international order after the end of World War II that sustained U.S. primacy.
In his view, realist predictions of power balancing did not bear fruit because the United States engaged in strategic restraint after World War II, thereby convincing weaker states that it was more interested in cooperation rather than domination. U.S. strategic restraint allowed weaker countries to participate in the make-up of the post-war world order, which limited opportunities for the United States to exploit total power advantages. Ikenberry notes that while the United States could have unilaterally engaged in unfettered power projection, it decided instead to "lock in" its advantage long after zenith by establishing an enduring institutional order, gave weaker countries a voice, reduced great power uncertainty, and mitigated the
security dilemma
In international relations, the security dilemma (also referred to as the spiral model) is when the increase in one state's security (such as increasing its military strength) leads other states to fear for their own security (because they do not k ...
. The liberal basis of U.S. hegemony—a transparent democratic political system—has made it easier for other countries to accept the post-war order, Ikenberry explains. "American hegemony is reluctant, open, and highly institutionalized—or in a word, liberal" and "short of large-scale war or a global economic crisis, the American hegemonic order appears to be immune to would-be hegemonic challengers."
Current debates
Scholars have debated whether the current international order (as of 2025) is characterized by unipolarity, bipolarity or multipolarity.
Michael Beckley argues American primacy is vastly underestimated because power indices frequently fail to take into account
GDP per capita
This is a list of countries by nominal GDP per capita. GDP per capita is the total value of a country's finished goods and services (gross domestic product) divided by its total population (per capita).
Gross domestic product (GDP) per capita is ...
in the U.S. relative to other purportedly powerful states, such as China and India. In 2011,
Barry Posen
Barry Ross Posen (born July 13, 1952) is Ford International Professor of Political Science at MIT and the director of MIT's Security Studies Program. An expert in the field of security studies, he currently serves on the editorial boards of the ...
argued that unipolarity was in wane and that the world was shifting towards multipolarity. In 2019,
John Mearsheimer
John Joseph Mearsheimer (; born December 14, 1947) is an American political scientist and international relations scholar. He is R. Wendell Harrison Distinguished Service Professor in the University of Chicago.
Mearsheimer is best known for dev ...
argued that the international system was shifting from unipolarity to multipolarity.
In 2022,
William Wohlforth argued that the international system was heading towards a system that can be characterized neither as bipolarity nor multipolarity. He added that polarity did not appear to matter as much in the current international system, as great powers command a far smaller share of power vis-a-vis the rest of the states in the international system. In 2023, Wohlforth and Stephen Brooks argued that the United States is still the unipole but that U.S. power has weakened and the nature of U.S. unipolarity has changed.
They add, "The world is neither bipolar nor multipolar, and it is not about to become either. Yes, the United States has become less dominant over the past 20 years, but it remains at the top of the global power hierarchy—safely above China and far, far above every other country... Other countries simply cannot match the power of the United States by joining alliances or building up their militaries."
Impact on conflict and cooperation
Scholars have debated the durability and peacefulness of unipolarity.
William Wohlforth argues that unipolarity is durable and peaceful because it reduces the likelihood of hegemonic rivalry (because no state is powerful enough to challenge the unipole) and it reduces the salience and stakes of balance of power politics among the major states, thus reducing the likelihood that attempts at balances of power cause major war.
Wohlforth builds his argument on
hegemonic stability theory
Hegemonic stability theory (HST) is a theory of international relations, rooted in research from the fields of political science, economics, and history. HST indicates that the international system is more likely to remain stable when a single sta ...
and a rejection of the
balance of power theory.
With no great power to check its adventurism, the United States will weaken itself by misusing its power internationally. "Wide latitude" of "policy choices" will allow the U.S. to act capriciously on the basis of "internal political pressure and national ambition."
Bruce Bueno de Mesquita has argued that the correlation between polarity of any kind and conflict is statistically weak, and depends critically on systemic uncertainty and risk attitudes among individual actors.
According to
Carla Norrlöf
Carla Norrlöf is a Swedish-Ethiopian political scientist. She is associate professor of Political Science at the University of Toronto. Her research focuses on hegemony, as well as the international political economy of trade, investment and secur ...
, U.S. unipolarity is stable and sustainable due to a combination of three factors: 1. The status of the American dollar as the world's dominant
reserve currency
A reserve currency is a foreign currency that is held in significant quantities by central banks or other monetary authorities as part of their foreign exchange reserves. The reserve currency can be used in international transactions, internat ...
, 2. American commercial power, and 3. American military preponderance. The United States benefits disproportionately from its status as hegemon. Other states do not challenge U.S. hegemony because many of them benefit from the U.S.-led order, and there are significant coordination problems in creating an alternative world order.
Nuno P. Monteiro argues that unipolarity is conflict-prone, both between the unipole and other states, and exclusively among other states.
Monteiro substantiates this by remarking that "the United States has been at war for thirteen of the twenty-two years since the end of the Cold War. Put another way, the first two decades of unipolarity, which make up less than 10 percent of
U.S. history, account for more than 25 percent of the nation's total time at war."
Kenneth Waltz
Kenneth Neal Waltz (; June 8, 1924 – May 12, 2013) was an American political scientist who was a member of the faculty at both the University of California, Berkeley, and Columbia University and one of the most prominent scholars in the field ...
that unipolarity is "the least durable of international configurations." Secondly, even if the United States acts benevolently, states will still attempt to balance against it because the power asymmetry demands it: In a self-help system, states do not worry about other states' intentions as they do other states' capabilities. "Unbalanced power leaves weaker states feeling uneasy and gives them reason to strengthen their positions," Waltz says.
In a 2009 study,
Martha Finnemore
Martha Finnemore (born 1959) is an American constructivist scholar of international relations, and professor at the Elliott School of International Affairs at George Washington University. She is considered among the most influential international ...
argues that unipolarity has, contrary to some expectations, not given the United States a free rein to do what it wants and that unipolarity has proven to be quite frustrating for the United States. The reasons for this is that unipolarity does not just entail a material superiority by the unipole, but also a social structure whereby the unipole maintains its status through legitimation, and institutionalization. In trying to obtain legitimacy from the other actors in the international system, the unipole necessarily gives those actors a degree of power. The unipole also obtains legitimacy and wards off challenges to its power through the creation of institutions, but these institutions also entail a diffusion of power away from the unipole.
In a 2021 study, Yuan-kang Wang argues from the experience of
Ming China
The Ming dynasty, officially the Great Ming, was an Dynasties of China, imperial dynasty of China that ruled from 1368 to 1644, following the collapse of the Mongol Empire, Mongol-led Yuan dynasty. The Ming was the last imperial dynasty of ...
(1368–1644) and
Qing China
The Qing dynasty ( ), officially the Great Qing, was a Manchu-led imperial dynasty of China and an early modern empire in East Asia. The last imperial dynasty in Chinese history, the Qing dynasty was preceded by the Ming dynasty ...
(1644–1912) that the durability of unipolarity is contingent on the ability of the unipole to sustain its power advantage and for potential challengers to increase their power without provoking a military reaction from the unipole.
Bipolarity
Bipolarity is a distribution of power in which two states have a preponderance of power. In bipolarity, spheres of influence and alliance systems have frequently developed around each pole. For example, in the
Cold War
The Cold War was a period of global Geopolitics, geopolitical rivalry between the United States (US) and the Soviet Union (USSR) and their respective allies, the capitalist Western Bloc and communist Eastern Bloc, which lasted from 1947 unt ...
of 1947–1991, most Western and capitalist states would fall under the influence of the US, while most Communist states would fall under the influence of the
USSR
The Union of Soviet Socialist Republics. (USSR), commonly known as the Soviet Union, was a List of former transcontinental countries#Since 1700, transcontinental country that spanned much of Eurasia from 1922 until Dissolution of the Soviet ...
. According to Wohlforth and Brooks, "the world was undeniably bipolar" during the Cold War.
Historic examples of bipolarity include
Great Britain
Great Britain is an island in the North Atlantic Ocean off the north-west coast of continental Europe, consisting of the countries England, Scotland, and Wales. With an area of , it is the largest of the British Isles, the List of European ...
and
France
France, officially the French Republic, is a country located primarily in Western Europe. Overseas France, Its overseas regions and territories include French Guiana in South America, Saint Pierre and Miquelon in the Atlantic Ocean#North Atlan ...
in 18th century from the end of the
War of the Spanish Succession
The War of the Spanish Succession was a European great power conflict fought between 1701 and 1714. The immediate cause was the death of the childless Charles II of Spain in November 1700, which led to a struggle for control of the Spanish E ...
(1701–1715) until the
Seven Years' War
The Seven Years' War, 1756 to 1763, was a Great Power conflict fought primarily in Europe, with significant subsidiary campaigns in North America and South Asia. The protagonists were Kingdom of Great Britain, Great Britain and Kingdom of Prus ...
(1754–1763), and the
United States
The United States of America (USA), also known as the United States (U.S.) or America, is a country primarily located in North America. It is a federal republic of 50 U.S. state, states and a federal capital district, Washington, D.C. The 48 ...
and the
Soviet Union
The Union of Soviet Socialist Republics. (USSR), commonly known as the Soviet Union, was a List of former transcontinental countries#Since 1700, transcontinental country that spanned much of Eurasia from 1922 until Dissolution of the Soviet ...
during the Cold War (1947–1991).
Impact on conflict and cooperation
Kenneth Waltz's influential ''
Theory of International Politics'' argued that bipolarity tended towards the greatest stability because the two great powers would engage in rapid mutual adjustment, which would prevent inadvertent escalation and reduce the chance of power asymmetries forming.
John Mearsheimer
John Joseph Mearsheimer (; born December 14, 1947) is an American political scientist and international relations scholar. He is R. Wendell Harrison Distinguished Service Professor in the University of Chicago.
Mearsheimer is best known for dev ...
also argued, that bipolarity is the most stable form of polarity, as buck passing is less frequent.
Dale C. Copeland has challenged Waltz on this, arguing that bipolarity creates a risk for war when a power asymmetry or divergence happens.
Multipolarity
Multipolarity is a distribution of power in which more than two states have similar amounts of power. The
Concert of Europe
The Concert of Europe was a general agreement among the great powers of 19th-century Europe to maintain the European balance of power, political boundaries, and spheres of influence. Never a perfect unity and subject to disputes and jockeying ...
, a period from after the
Napoleonic Wars
{{Infobox military conflict
, conflict = Napoleonic Wars
, partof = the French Revolutionary and Napoleonic Wars
, image = Napoleonic Wars (revision).jpg
, caption = Left to right, top to bottom:Battl ...
to the
Crimean War
The Crimean War was fought between the Russian Empire and an alliance of the Ottoman Empire, the Second French Empire, the United Kingdom of Great Britain and Ireland, and the Kingdom of Sardinia (1720–1861), Kingdom of Sardinia-Piedmont fro ...
, was an example of peaceful multipolarity (the great powers of Europe assembled regularly to discuss international and domestic issues), as was the
Interwar period
In the history of the 20th century, the interwar period, also known as the interbellum (), lasted from 11 November 1918 to 1 September 1939 (20 years, 9 months, 21 days) – from the end of World War I (WWI) to the beginning of World War II ( ...
.
Examples of wartime multipolarity include
World War I
World War I or the First World War (28 July 1914 – 11 November 1918), also known as the Great War, was a World war, global conflict between two coalitions: the Allies of World War I, Allies (or Entente) and the Central Powers. Fighting to ...
,
World War II
World War II or the Second World War (1 September 1939 – 2 September 1945) was a World war, global conflict between two coalitions: the Allies of World War II, Allies and the Axis powers. World War II by country, Nearly all of the wo ...
, the
Thirty Years War
The Thirty Years' War, fought primarily in Central Europe between 1618 and 1648, was one of the most destructive conflicts in European history. An estimated 4.5 to 8 million soldiers and civilians died from battle, famine, or disease, whil ...
, the
Warring States period
The Warring States period in history of China, Chinese history (221 BC) comprises the final two and a half centuries of the Zhou dynasty (256 BC), which were characterized by frequent warfare, bureaucratic and military reforms, and ...
, the
Three Kingdoms
The Three Kingdoms of Cao Wei, Shu Han, and Eastern Wu dominated China from AD 220 to 280 following the end of the Han dynasty. This period was preceded by the Eastern Han dynasty and followed by the Jin dynasty (266–420), Western Jin dyna ...
period and the tripartite division between
Song dynasty
The Song dynasty ( ) was an Dynasties of China, imperial dynasty of China that ruled from 960 to 1279. The dynasty was founded by Emperor Taizu of Song, who usurped the throne of the Later Zhou dynasty and went on to conquer the rest of the Fiv ...
/
Liao dynasty/
Jin dynasty/
Yuan dynasty
The Yuan dynasty ( ; zh, c=元朝, p=Yuáncháo), officially the Great Yuan (; Mongolian language, Mongolian: , , literally 'Great Yuan State'), was a Mongol-led imperial dynasty of China and a successor state to the Mongol Empire after Div ...
.
Impact on conflict and cooperation
Classical realist theorists, such as
Hans Morgenthau
Hans Joachim Morgenthau (February 17, 1904 – July 19, 1980) was a German-American jurist and political scientist who was one of the major 20th-century figures in the study of international relations. Morgenthau's works belong to the tradition ...
and
E. H. Carr, hold that multipolar systems are more stable than bipolar systems, as great powers can gain power through alliances and petty wars that do not directly challenge other powers; in bipolar systems, classical realists argue, this is not possible.
Neorealists hold that multipolar systems are particularly unstable and conflict-prone, as there is greater complexity in managing alliance systems, and a greater chance of misjudging the intentions of other states.
Thomas Christensen and
Jack Snyder argue that multipolarity tends towards instability and conflict escalation due to "
chain-ganging" (allies get drawn into unwise wars provoked by alliance partners) and "
buck-passing" (states which do not experience an immediate proximate threat do not balance against the threatening power in the hope that others carry the cost of balancing against the threat). John Mearsheimer also argues that buck passing is more common in multipolar systems.
Multipolarity does not guarantee
multilateralism
In international relations, multilateralism refers to an alliance of multiple countries pursuing a common goal. Multilateralism is based on the principles of inclusivity, equality, and cooperation, and aims to foster a more peaceful, prosperous, an ...
and can pose a challenge against multilateralism.
According to
Kemal Derviş, a decline in unipolarity creates a crisis in multilateralism; it is possible to revive multilateralism in a multipolar system, but this is more threatened and the structure to do so is not fully developed.
In multipolarity, larger powers can negotiate "mega-regional" agreements more easily than smaller ones. When there are multiple competing great powers, this can lead to the smaller states being left out of such agreements.
Though multipolar orders form regional hegemonies around 'poles' or great powers, this can weaken economic interdependencies within regions, at least in regions without a great power. Additionally, as multipolar systems can tend to regional hegemonies or bounded orders, agreements are formed within these bounded orders rather than globally. Though, Mearsheimer predicts the persistence of a thin international order within multipolarity, which constitutes some multilateral agreements.
The term multipolarity has been used to describe the development of close relations between China and the Russian Federation after the Cold War, emerging out of the shared goal to disrupt American leadership in the international system. According to Edina Julianna Haiszky, the Russian-Chinese alliance to create a multipolar international system is informed by their self-perception as independent civilisations rather than nation-states, precipitating a political desire to act as active shapers of the international system.
Measuring the power concentration
The
Correlates of War
The Correlates of War project is an academic study of the history of warfare. It was started in 1963 at the University of Michigan by political scientist J. David Singer. Concerned with collecting data about the history of wars and conflict among s ...
uses a systemic concentration of power formula to calculate the polarity of a given
great power
A great power is a sovereign state that is recognized as having the ability and expertise to exert its influence on a global scale. Great powers characteristically possess military and economic strength, as well as diplomatic and soft power ...
system. The formula was developed by
J. David Singer et al. in 1972.
:
:''t'' = the time at which the concentration of resources (i.e. power) is being calculated
:''i'' = the state of which the proportion of control over the system's power is being measured
:''N''
''t'' = the number of states in the great power system at time ''t''
:''S'' = the
proportion of power possessed. Hence, ''S''
''it'' = the proportion of power possessed by state ''i'' at time ''t''.
The expression
represents the sum of the squares of the proportion of power possessed by all states in the great power system.
The closer the resulting concentration is to zero, the more evenly divided power is. The closer to 1, the more concentrated power is. There is a general but not strict correlation between concentration and polarity. It is rare to find a result over 0.5, but a result between 0.4 and 0.5 usually indicates a unipolar system, while a result between 0.2 and 0.4 usually indicated a bipolar or multipolar system. Concentration can be plotted over time, so that the fluctuations and trends in concentration can be observed.
See also
*
Balance of power (international relations)
The balance of power theory in international relations suggests that states may secure their survival by preventing any one state from gaining enough military power to dominate all others. If one state becomes much stronger, the theory predicts ...
*
Bipolarisation
Bipolarisation or bipolarization (American English) in politics, is a state where forces are organized around two rival powers, neither of which can dominate the other. Its application as a model for international relations has given rise to dive ...
*
Global policeman
*
Global Swing States
*
International monetary systems
An international monetary system is a set of internationally agreed rules, conventions and supporting institutions that facilitate international trade, cross border investment and generally the reallocation of capital between states that have dif ...
*
Non-Aligned Movement
The Non-Aligned Movement (NAM) is a forum of 121 countries that Non-belligerent, are not formally aligned with or against any major power bloc. It was founded with the view to advancing interests of developing countries in the context of Cold W ...
*
Pax Americana
*
Pax Britannica
''Pax Britannica'' (Latin for , modelled after '' Pax Romana'') refers to the relative peace between the great powers in the time period roughly bounded by the Napoleonic Wars and World War I. During this time, the British Empire became the ...
*
Power (international relations)
In international relations, power is defined in several different ways. Material definitions of state power emphasize economic and military power. Other definitions of power emphasize the ability to structure and constitute the nature of social ...
*
Posthegemony
*
Regional hegemony
*
Thucydides Trap
Bibliography
* Thompson, William R. ''On Global War: Historical–Structural Approaches to World Politics.'' Columbia, SC: University of South Carolina Press, 1988, pp. 209–210.
Notes
References
External links
Global Power Barometer
{{DEFAULTSORT:Polarity In International Relations
International relations theory