Realism: Realists grant a marginal role to the international organizations. For Realist thinkers, states are principal international actors, and international organizations (for them, it refers to intergovernmental organizations not international non-governmental organizations) only matters if they serve interests of states. According Realist thinkers, international politics have an anarchic structure in which there is no common authority over and above the sovereign state, or a lack of government at the international level. Realists claim that in anarchic international system, states cannot trust each other and they always fear of cheating and thus this makes interstate cooperation difficult to achieve. For Realists, main motivation of states in anarchic international system is survival, i.e. preserving the existence of the state, because of this, states cannot rely on other states or international organizations for their defence and must rely on its own resources for survival, which is called as self-help. Realists claim that international organizations are just instruments used by states in their quest for power and interest. Realists also believe that another factor which makes interstate cooperation difficult to achieve is that states are preoccupied with making relative gains (improvements in a state’s position relative to other states).