42 Ronald L.Tammen and Jacek Kugler There is substantial empirical support for the power parity proposition throughout the conflict literature.4In other research environments,such formal and empirical evidence would have been sufficient to challenge the fundamental assertion that a parity or 'balance of power'preserves peace. However,given the widely held belief among practitioners and academics that the underlying logic of balance of power is correct,these two research directions continue to develop side by side.The collapse of the Soviet Union is one such critical test that has awakened the need to reformulate long-held beliefs. No one can argue today that Russia presents a direct threat to the Western world or that another challenger of a similar magnitude is already in place; yet stability increased after the decline of the Soviet Union.Further,the emergence of asymmetry in nuclear weapons combined with the re-targeting of such weapons by both the United States and Russia make it difficult to argue that Mutual Assured Destruction continues to preserve the existing stability in the international system. Probability of Conflict at the Global Level Power parity provides the structural conditions for conflict and cooperation. While power is central to the deductions of balance of power and 14 Organski and Kugler,using the record of major wars among the main Western powers, show that power parity and transition set the necessary conditions for major wars waged between 1870 and 1970.See A.F.K.Organski and Jacek Kugler,The War Ledger (Chicago: Chicago University Press,1980).Likewise.Woosang Kim.Houweling and Siccama.and Bremer and Cusack show that in the last two centuries parity is a pre-condition for the most severe confrontation in the international system.Moreover.Werner and Kugler show that if one considers all protracted crises emerging from the presence of a festering dispute,parity accounts for almost all the incidences of major power war recorded in the last two centuries when a challenger manages to outspend the defender in military preparedness.See Jacek Kugler and Douglas Lemke eds,Parity and War. An important extension of the power parity perspective by Lemke demonstrates that the same principles that hold true among the major powers at the global level also hold true among regional leaders.Lemke's contribution is essential because he shows that severe conflicts of all types follow conditions of power parity.His empirical tests,based on very diverse regions of Latin America,the Middle East and Africa,demonstrate that the same conditions that lead to major confrontations among the largest nations in the international system hold true for major competitors in key regions.See Douglas Lemke,Regions of War and Peace (Cambridge:Cambridge University Press.2002). Finally,Bueno de Mesquita and Lalman use a sophisticated bounded rationality approach to show formally that while conditions for conflict and peace in the balance of power are inconsistent,the conditions identified by power parity are consistent with the prevailing evidence.See Bueno de Mesquita and David Lalman,War and Reason:Domestic and International Imperatives (New Haven:Yale University Press.1992).Extensions of this approach to nuclear deterrence demonstrate the consistency of the parity argument with post-war behaviour,but indicate that Mutual Assured Destruction is logically a tenuous strategy as deterrence may fail when risk propensity is high and prone to instability.see Jacek Kugler and Frank Zagare,The Stability of Deterrence (Boulder:Lynne Rienner Publishers,1987);Frank Zagare,Reconciling Rationality with Deterrence:A Re-Examination of the Logical Foundations of Deterrence Theory',Journal of Theoretical Politics,Vol.16,No.2.(2004). Chinese Journal of International Politics,Vol.1,2006,35-55There is substantial empirical support for the power parity proposition throughout the conflict literature.14 In other research environments, such formal and empirical evidence would have been sufficient to challenge the fundamental assertion that a parity or ‘balance of power’ preserves peace. However, given the widely held belief among practitioners and academics that the underlying logic of balance of power is correct, these two research directions continue to develop side by side. The collapse of the Soviet Union is one such critical test that has awakened the need to reformulate long-held beliefs. No one can argue today that Russia presents a direct threat to the Western world or that another challenger of a similar magnitude is already in place; yet stability increased after the decline of the Soviet Union. Further, the emergence of asymmetry in nuclear weapons combined with the re-targeting of such weapons by both the United States and Russia make it difficult to argue that Mutual Assured Destruction continues to preserve the existing stability in the international system. Probability of Conflict at the Global Level Power parity provides the structural conditions for conflict and cooperation. While power is central to the deductions of balance of power and 14 Organski and Kugler, using the record of major wars among the main Western powers, show that power parity and transition set the necessary conditions for major wars waged between 1870 and 1970. See A.F.K. Organski and Jacek Kugler, The War Ledger (Chicago: Chicago University Press, 1980). Likewise, Woosang Kim, Houweling and Siccama, and Bremer and Cusack show that in the last two centuries parity is a pre-condition for the most severe confrontation in the international system. Moreover, Werner and Kugler show that if one considers all protracted crises emerging from the presence of a festering dispute, parity accounts for almost all the incidences of major power war recorded in the last two centuries when a challenger manages to outspend the defender in military preparedness. See Jacek Kugler and Douglas Lemke eds, Parity and War. An important extension of the power parity perspective by Lemke demonstrates that the same principles that hold true among the major powers at the global level also hold true among regional leaders. Lemke’s contribution is essential because he shows that severe conflicts of all types follow conditions of power parity. His empirical tests, based on very diverse regions of Latin America, the Middle East and Africa, demonstrate that the same conditions that lead to major confrontations among the largest nations in the international system hold true for major competitors in key regions. See Douglas Lemke, Regions of War and Peace (Cambridge: Cambridge University Press, 2002). Finally, Bueno de Mesquita and Lalman use a sophisticated bounded rationality approach to show formally that while conditions for conflict and peace in the balance of power are inconsistent, the conditions identified by power parity are consistent with the prevailing evidence. See Bueno de Mesquita and David Lalman, War and Reason: Domestic and International Imperatives (New Haven: Yale University Press, 1992). Extensions of this approach to nuclear deterrence demonstrate the consistency of the parity argument with post-war behaviour, but indicate that Mutual Assured Destruction is logically a tenuous strategy as deterrence may fail when risk propensity is high and prone to instability, see Jacek Kugler and Frank Zagare, The Stability of Deterrence (Boulder: Lynne Rienner Publishers, 1987); Frank Zagare, ‘Reconciling Rationality with Deterrence: A Re-Examination of the Logical Foundations of Deterrence Theory’, Journal of Theoretical Politics, Vol.16, No. 2. (2004). 42 Ronald L. Tammen and Jacek Kugler Chinese Journal of International Politics, Vol. 1, 2006, 35–55