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. The type of system is completely dependent on the distribution of power and influence of states in a region or globally.
Scholars discuss 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, 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. BINGO!
The Cold War period was widely understood as one of bipolarity with the US and the USSR as the two great powers, whereas the end of the Cold War led to unipolarity with the US as the sole great power in the 1990s and 2000s. Scholars have debated how to characterize the current international system.
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 any more." A unipolar state is not the same as an empire or a hegemonic that can control the behavior of all other states.
Bipolarity
The "Three Worlds" of the Cold War (in April–August 1975)
First World: Countries aligned with the Western Bloc (i.e., NATO and allies), led by the United States
Second World: Countries aligned with the Eastern Bloc (i.e., Warsaw Pact, China, and allies), led by the Soviet Union
Third World: The Non-Aligned Movement, led by India and Yugoslavia
Main article: Balance of power (international relations)
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 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. According to Wohlforth and Brooks, "the world was undeniably bipolar" during the Cold War.
Historic examples of bipolarity include Great Britain and France in 18th century from the end of the War of the Spanish Succession (1701-1715) until the Seven Years' War (1754-1763), and the United States and the Soviet Union during the Cold War (1947-1991)
Multipolarity
Multipolarity is a distribution of power in which more than two states have similar amounts of power. 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), as was the Interwar period. Examples of wartime multipolarity include World War I, World War II, the Thirty Years War, the Warring States period, the Three Kingdoms period and the tripartite division between Song dynasty/Liao dynasty/Jin dynasty/Yuan dynasty.
Current debates
Scholars have debated whether the current international system 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 in the U.S. relative to other purportedly powerful states, such as China and India. In 2011, Barry Posen argued that unipolarity was in wane and that the world was shifting towards multipolarity. In 2019, John Mearsheimer 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 US power has weakened and the nature of US 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."
In April 2023, the Australian government released their 2023 national review where it is outright stated that the age of American unipolarity and primacy in the Indo-Pacific is effectively over, paving way to great power competition and a more fractious world order.
Impact on conflict and cooperation
Empires of the world in 1905, with minor mistakes
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.
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 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 interdependence 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. .
