the sole judge their own behaviors, and subject to no higher actors are gher than the nation-state, also believe that all subordina e nation-state. While private citizens can inter r coun rparts in other countries, Realists assert that the basis egislated by the nation-state. Thus, where Liberals for this interaction focus on individuals and Marxists on classes. Realists concentrate on on States Second, Realists assume that nation-states are power maximizers Because the intemational system is based upon anarchy, the or use of coercion by nation-states is always a possibility and no other or higher authority is obligated to to the aid of a nation-state un attack. ation-states are thus ultimately dependent upon thei own resources for protection. For Realists, then, each nation-state must always prepared to defend itself to the best of its ability. must always seek to maximize its power; the failure to do so threatens the very existence of the nation-state and may make it vulnerable to others. Power is a relative c cept. If one nation-state (or any other actor) expands s power over anothe can do so only at the expense of the second. Thus, for Realists, politics s a zero-sum game and by necessity conflictual. If one nation-state wins, another must los Third, Realists assume that nation-states are rational actors in the same sense that Liberals assume individuals are rational. Nation-states are assumed to perform cost-benefit analyses and choose the option which yields greatest value. in this case, the one which maximizes pow lu is the assumption of power maxim on that gives Realism its dis- tinctive approach to International Political Economy. While economic con- siderations often complement power concerns, the former are in the Realist subordinate to the latter. Liberals and Marxists see individu als and classes, respectively, as always seeking to maximize their economic well-being. Realists, on the other hand, allow for circumstances in which nation-states sacrifice economic gain to weaken their opponents or strengthen themselves in military or diplomatic terms. Thus, trade prote tion-which might reduce a country's overall income by restricting the market be adopted for reasons of national political power. Given its assomptions. Realist political economy is primarily co cerned with how changes in the distribution of international power affect the form and type of international econom The best known Realist approach to this question is the "theory of hegemonic stabilit w holds that an open international economy. hat is, one characterized by the free exchange of goods, capital, and services-is most likely to exist single dominant or hegemonic power is present to stabilize the system and construc a strong regime. For Realists then, politics underlies eco nomics. In the pursuit of power, nation-states shape the intermational my to best serve their desired ends