# Polarity (international relations)

Polarity in international relations 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.[1] The type of system is completely dependent on the distribution of power and influence of states in a region or globally.

Scholars differ as to whether bipolarity or unipolarity is likely to produce the most stable and peaceful outcomes. Kenneth Waltz and John Mearsheimer are among those who argue that bipolarity tends to generate relatively more stability,[2][3] whereas John Ikenberry and William Wohlforth are among those arguing for the stabilizing impact of unipolarity. Some scholars, such as Karl Deutsch and J. David Singer, argued that multipolarity was the most stable structure.[4]

International Relations scholars widely view the post–Cold War international system as unipolar due to American superiority in commercial power and military spending, as well as the role of U.S. dollar as the world's dominant reserve currency and U.S. influence in dominant international organizations.[5][6][7] In terms of military power, Nuno Monteiro writes that American defense spending is "close to half of global military expenditures; a blue-water navy superior to all others combined; a chance at a powerful nuclear first strike over its erstwhile foe, Russia; a defense research and development budget that is 80 percent of the total defense expenditures of its most obvious future competitor, China; and unmatched global power-projection capabilities."[8]

Scholars disagree about the sources and stability of U.S. unipolarity. Realist international relations scholar argue that unipolarity is rooted in the superiority of U.S. material power since the end of the Cold War. Liberal international relations scholar John Ikenberry attributes U.S. hegemony in part to what he says are commitments and self-restraint that the United States established through the creation of international institutions (such as the United Nations, International Monetary Fund, World Bank, and World Trade Organization). Constructivist scholar Martha Finnemore argues that legitimation and institutionalization are key components of unipolarity.

## Unipolarity

Unipolarity in international politics is a distribution of power in which one state exercises most of the cultural, economic, and military influence.

Unipolar systems are not the same as empire.[8] Robert Jervis argues that “unipolarity implies the existence of many juridically equal nation-states, something that an empire denies.”[9] Daniel Nexon and Thomas Wright write “in empires, inter-societal divide-and-rule practices replace interstate balance-of-power dynamics.”[10]

Unipolarity happens in anarchical international systems.[8]

In unipolar systems, there is only one great power and no real competition. If a competitor emerges, the international system is no longer unipolar.[8]

William Wohlforth believes unipolarity is peaceful because

Unipolarity favors the absence of war among great powers and comparatively low levels of competition for prestige or security for two reasons: the leading state’s power advantage removes the problem of hegemonic rivalry from world politics, and it reduces the salience and stakes of balance of power politics among the major states.[11]

According to Wohlforth, “Therefore one pole is best, and security competition among the great powers should be minimal.”[11] Unipolarity generates few incentives for security and prestige competition among great powers. This idea is based on hegemonic stability theory and the rejection of the balance of power theory. Hegemonic stability theory stipulates that

[P]owerful states (“hegemons”) foster international orders that are stable until differential growth in power produces a dissatisfied state with the capability to challenge the dominant state for leadership. The clearer and larger the concentration of power in the leading state, the more peaceful the international order associated with it will be.[11]

The balance of power theory, by contrast, stipulates that as long as the international system remains in balance (without unipolar power), peace is maintained.

Nuno P. Monteiro argues that international relations theorists have long debated the durability of unipolarity (i.e. when it will end) but have had less debate about the relative peacefulness unipolarity brings among nations within an international system. Rather than comparing the relative peacefulness of unipolarity, multipolarity, and bipolarity, he identifies causal pathways to war that are endemic to a unipolar system. Monteiro does not question the impossibility of great power war in a unipolar world, which is a central tenet of Wohlforth in his book World Out of Balance: International Relations and the Challenge of American Primacy. Instead he believes “unipolar systems provide incentives for two other types of war: those pitting the sole great power against a relatively weaker state and those exclusively involving weaker states.”[8] Monteiro's hypothesis is influenced by the first two decades of the post–Cold War environment, one that is defined as unipolar and rife with wars. Monteiro writes, “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.”[8]

In a 2009 study, Martha Finnemore argues, contrary to some expectations, that unipolarity has 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.[12]

In a 2021 study, Yuan-kang Wang argues from the experience of Ming China (1368–1644) and Qing China (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.[13]

In 2019, John Mearsheimer argued that the international system was shifting from unipolarity to multipolarity.[14]

## American primacy

Numerous thinkers predicted U.S primacy in the 20th century onwards, including William Gladstone,[a][15] Michel Chevalier,[16] K'ang Yu-wei,[17] Georges Vacher de Lapouge,[18] H. G. Wells in Anticipations (1900),[19] and William Thomas Stead.

Michael Beckley argues American primacy is vastly underestimated because power indices frequently fail to take into account GDP per capita in the U.S. relative to other purportedly powerful states, such as China and India.[20]

### Kenneth Waltz

Kenneth Waltz, the founder of Neorealism, in his epochal Theory of International Politics (1979) precluded the possibility of unipolarity. Two, he stated (1979: 136), is the smallest possible number of poles in a system. Within twelve years, unipolarity emerged. In two papers of 1993--“Structural Realism after the Cold War” and "The Emerging Structure of International Politics"—Waltz defends the neorealist theory against a cascade of criticism that emerged after the Cold War. First of all, he stresses that unipolarity is “the least durable of international configurations.”[21] He provides a realist analysis of the currently unipolar structure of world politics, arguing that realism is the best theoretical lens to understanding international politics and the short future of U.S. primacy.

Waltz also takes on democratic peace theory, which holds that no two democracies will go to war with each other, as one that doesn't present a proper challenge to realism. War is rooted in the anarchic structure, or a self-help environment, of the international system, Waltz argues. Simply changing the domestic political structure of countries will not eliminate war, Waltz notes. However, “democracies seldom fight democracies”,[22] although democracies are more likely to initiate wars against non-democracies because the former believes the latter must become democratized so as to make the democratic peace more robust. Thus, the spread of democracy can decrease the amount of war in the world in Waltz's view. The second challenge to realist theory argues that economic interdependence promotes peace. Waltz believes this causal logic is backward: Peace can promote economic interdependence. Peace abounds when a political monopoly on force, or a favorable balance of power, prevents revisionist powers from altering the status quo. After all, Waltz argues, strong economic interdependence did not prevent war in 1914.

The third challenge that Waltz confronts is the rise of international institutions as primary actors in international politics. Waltz argues that the structure of power in the international system determines the role of institutions. NATO, for example, is often cited as an institution that has outlived its original mandate—preventing a Soviet onslaught of Western Europe. In Waltz's view, NATO's continued existence conveniently “illustrates how international institutions are created and maintained by stronger states (e.g., the United States) to serve their perceived and misperceived interests.”[22] Finally, Waltz turns to the question of international politics and provides a realist interpretation to the U.S. unipolar moment, which he believes is fleeting for two reasons. 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.”[22] 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.[22] He sees China as already beginning to counter U.S. power. In conclusion, the U.S. unipolar moment is fleeting and multipolarity is already materializing.

In 1964, Waltz maintained that the United States was the only “pole” to possess global interests.[23]

Waltz 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.[2] Dale Copeland has challenged Waltz on this, arguing that bipolarity creates a risk for war when a power asymmetry or divergence happens.[24]

### John Ikenberry

In “Institutions, Strategic Restraint, and Persistence of American Postwar Order,” John Ikenberry explains why other great powers decided not to balance against the United States after the Cold War ended.[25] 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[26] by establishing an enduring institutional order, gave weaker countries a voice, reduced great power uncertainty, and mitigated the security dilemma, a concept known as Lock in thesis[26] 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.”[7]

### Barry Posen

In “Command of the Commons: The Military Foundation of U.S. Hegemony,” Barry Posen focuses exclusively on U.S. military capabilities. A key to U.S. preeminence is “command of the commons—command of the sea, space, and air.” But command of the commons and the U.S. persistence in maintaining its near omnipresence raise important questions for U.S. strategy: “Even before the September 11 terrorist attacks, the foreign policy debate had narrowed to a dispute between primacy and selective engagement, between nationalist, unilateralist version of hegemony, and a liberal, multilateral version of hegemony.”[27] U.S. command of the commons, Posen argues, provides a strong case for selective engagement. Posen believes that the Bush Doctrine was problematic because it not only created unease among U.S. allies, but also caused “others to ally against the United States.”[27] Securing the commons through selective engagement is a superior strategy because it is cost effective, secures U.S. interests, and makes the nearly omnipresent U.S. military tolerable because it provides security guarantees to other nations.

### Carla Norrlöf

According to Carla Norrlöf, 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, 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.[5]

## Bipolarity

Bipolarity is a distribution of power in which two states have the majority of economic, military, and cultural influence internationally or regionally.[28] Often, spheres of influence would develop. For example, in the Cold War, 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. After this, the two powers will normally maneuver for the support of the unclaimed areas. Which in the case of the Cold War means Africa, etc. (refer to map below).

Spheres of influence of the two Cold War superpowers (the US and the USSR) in 1959.
The "First World": NATO members (dark blue) and their "Western" allies (light blue).
The "Second World": Warsaw Pact signees (red) and their Socialist allies (pink).
The "Third World": Neutral nations (grey) and Colonies (green).

## Multi-state examples of bipolarity

The bipolar system can be said to extend to much larger systems, such as alliances or organizations, which would not be considered nation-states, but would still have power concentrated in two primary groups.

In both World Wars, much of the world, and especially Europe, the United States, and Japan had been divided into two respective spheres – one case being the Axis and Allies of World War II (1939–1945) – and the division of power between the Central Powers and Allied powers during World War I (1914–1918). Neutral nations, however, may have caused what may be assessed as an example of tripolarity as well within both of the conflicts.

The NATO and Warsaw Pact groupings could also be considered to be bipolar if one does not include the Non-Aligned Movement.

According to Sullivan and Donnelly, a "polycentric" period emerged between 1963-1988 in contrast to the bipolar period of 1945-1962.[29]

## Multipolarity

Multipolarity is a distribution of power in which more than two nation-states have nearly equal amounts of military, cultural, and economic influence.

Empires of the world in 1905, with minor mistakes.

Opinions on the stability of multipolarity differ. Classical realist theorists, such as Hans Morgenthau 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.

On the other hand, the neorealist focuses on security and inverts the formula: states in a multipolar system can focus their fears on any number of other powers and, misjudging the intentions of other states, unnecessarily compromise their security, while states in a bipolar system always focus their fears on one other power, meaning that at worst the powers will miscalculate the force required to counter threats and spend slightly too much on the operation. However, due to the complexity of mutually assured destruction scenarios, with nuclear weapons, multipolar systems may be more stable than bipolar systems even in the neorealist analysis. This system tends to have many shifting alliances until one of two things happens. Either a balance of power is struck, and neither side wants to attack the other, or one side will attack the other because it either fears the potential of the new alliance, or it feels that it can defeat the other side.

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).[30]

One of the major implications of an international system with any number of poles, including a multi polar system, is that international decisions will often be made for strategic reasons to maintain a balance of power rather than out of ideological or historical reasons.

The 'Concert of Europe,' a period from after the Napoleonic Wars to the Crimean War, was an example of peaceful multipolarity (the great powers of Europe assembled regularly to discuss international and domestic issues),[31] as was the Interwar period.[29] Examples of wartime multipolarity include World War I,[32] World War II,[33] the Thirty Years War,[34] the Warring States period,[35] the Three Kingdoms period and the tripartite division between Song dynasty/Liao dynasty/Jin dynasty/Yuan dynasty..

Multipolarity does not guarantee multilateralism and can pose a challenge against multilateralism.[36][37] 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.[36] 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.[37] 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.[38] 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.[39]

## Nonpolarity

Nonpolarity is an international system which has been postulated by Richard Haass, featuring numerous centers of power but no center dominating any other center. Centers of power can be nation-states, corporations, non-governmental organizations, terrorist groups, and such. Power is found in many hands and many places.[40] It suffers from attempting to use liberal conceptions of power within a realist paradigm, diluting the meaning of 'polarity', and is not widely found in usual discussions of polarity.[41]

## Measuring the power concentration

The Correlates of War uses a systemic concentration of power formula to calculate the polarity of a given great power system. The formula was developed by J. David Singer et al. in 1972.[42]

${\displaystyle {\text{Concentration}}_{t}={\sqrt {\frac {\sum _{i=1}^{N_{t}}(S_{it})^{2}-{\frac {1}{N_{t}}}}{1-{\frac {1}{N_{t}}}}}}}$
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
Nt = the number of states in the great power system at time t
S = the proportion of power possessed. Hence, Sit = the proportion of power possessed by state i at time t.

The expression ${\displaystyle \sum _{i=1}^{n}(S_{it})^{2}}$ 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.

## 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

1. ^ Alexis de Tocqueville in the mid-19th century had expected the bipolar world centered on America and Russia but had not advanced beyond bipolarity.

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