enforcing the rules of the system. After World War I, the United States possessed the capacity to lead, but lacked the will to do so. Without the will to force stability on the international system, the United States missed an opportunity to prevent the onset of the Great Depression or World War II. A hegemon must commit to the system, which needs to be perceived as mutually beneficial by other great powers and important state-actors. Competing theories of hegemonic stability Research on hegemony can be divided into two schools of thought: the realist school and the systemic school. Each school can be further sub-divided. Two dominant theories have emerged from each school. What Robert Keohane first called the "theory of hegemonic stability," joins A. F. K. Organski's Power Transition Theory as the two dominant approaches to the realist school of thought. Long Cycle Theory, espoused by George Modelski, and World Systems Theory, espoused by Immanuel Wallerstein, have emerged as the two dominant approaches to the systemic school of thought. The systemic school of thought According to Thomas J. McCormick, scholars and other experts on the systemic school define hegemony "as a single power's possession of 'simultaneous superior economic efficiency in production, trade and finance.'" Furthermore, a hegemon's superior position is considered the logical consequence of superior geography, technological innovation, ideology, superior resources, and other factors. Long cycle theory George Modelski, who presented his ideas in the book, Long Cycles in World Politics (1987), is the chief architect of long cycle theory. In a nutshell, long cycle theory describes the connection between war cycles, economic supremacy, and the political aspects of world leadership. Long cycles, or long waves, offer interesting perspectives on global politics by permitting "the careful exploration of the ways in which world wars have recurred, and lead states such as Britain and the United States have succeeded each other in an orderly manner." Not to be confused with Simon Kuznets' idea of long-cycles, or long-swings, long cycles of global politics are patterns of past world politics. The long cycle, according to Dr. Dan Cox, is a period of time lasting approximately 70 to 100 years. At the end of that period, "the title of most powerful nation in the world switches hands.". Modelski divides the long cycle into four phases. When periods of global war, which could last as much as one-fourth of the total long cycle, are