Multipolarity
A polarity condition in which three or more great powers dominate an international system — much of European history before 1945 is the standard example. Kenneth Waltz argued multipolar systems are less stable than bipolar ones because each great power must track several potentially shifting rivals at once, raising the risk of miscalculation (the alliance cascade that produced World War I being the illustrative case); John Mearsheimer complicated this by arguing unbalanced multipolarity (one especially powerful state among several others) is more dangerous than either bipolarity or a more evenly balanced multipolarity.