The research on legitimacy and the responsibilities of great powers could only be appropriately understood within the framework of international society .Because the international society is founded on evolving principles of legitimacy,the core principle of which requires a willingness to be bound by a socially-derived set of constraints as conditions for membership .The constraints include both particular conceptions of rightful membership of the international society,and particular conceptions of rightful conduct within it . Essentially,the social constraints are the obligations which states as members of international society should fulfill . Each state's obligations come from its membership status . The members of that community relinquish their absolute sovereignty in exchange for membership,and they are willing to accept constraints of a set of generally applicable principles and rules .Therefore,if a state would like to obtain recognition from other states,the prerequisite is that the state must fulfill the basic obligations of membership in the international society .The most fundamental obligation of a state is its compliance with the principle of sovereign equality among states . Besides members' general responsibilities,there are some particular responsibilities that could only be fulfilled by the few great powers or membership of the great powers club in the international society .The very distribution of this special responsibility is also often contingent on other states' recognition,which in turn is closely related to the concept of legitimacy .The concept of great powers includes both normative and empirical underpinnings .Great powers need not only strong material capabilities,but also other states' recognition of its special role in the international system .Only when a great power assumes special responsibilities commensurate to its capabilities can it obtain other states' recognition .This recognition grants the great power legitimacy and justifies its having certain privileges and responsibilities .Therefore,great powers' special privileges are intricately linked with its special responsibilities .Great powers endowed with special responsibility are benefit for the great powers and the small powers,because it creates a legitimate social power .Among these special responsibilities are :to manage relations with fellow great powers,especially in doing their utmost to prevent the most explicit competition and conflicts among themselves,to curtail those behaviors that disturb international order,to protect the weak states,and to assist the impoverished states . The distribution of special responsibilities could be also understood as an unique practice of legitimation and a balancing practice between respecting sovereign equality among all states and preserving special privileges of the great powers .Since the signing of the Treaty of Westphalia,the contradiction between the principle of the nation's sovereign equality and the uneven allocation of material power damaged the orderly operation of European international society .The major solution to this contradiction is to grant great powers certain special rights and responsibilities on top of the general principle of sovereignty equality .And an important way to legitimize great power's special status is to obtain other states' recognition .Although the precise allocation of special responsibility may oscillate from time to time,sometimes special status of the great powers may carry more weight,such as during the Congress of Vienna and the Concert of Europe that follows it .Other times,like the Congress of Paris and the League of Nations at post-World War I,the pendulum may swing more towards the principle of sovereign equality . However,the international arrangement is always assured through compliance with the legitimacy principle .In short,the regulation and allocation of great powers' special responsibility is essentially a method to solve the contradiction between the principle of sovereign equality and the unequal allocation of material powers,with the aim of ensuring orderly operation of the international order .