States and other institutions use their military, economic, and political power to try to influence the structure of the international environment so that it aligns with their preferences. Political actors may use each of these levers of power in an aggressive fashion, as when one state sends troops to invade another state or when one state interferes in another state’s elections, or they can employ soft power in friendlier interactions involving diplomacy, recognition, and cultural exchange. The level of success with which these actors are able to achieve their preferred ends communicates their power relative to the other members of the international system.
A state is a political entity with geographic boundaries and a system of government that is recognized as legitimate by the people it governs and by the international system as a whole. States can come together in international organizations to solve common problems. More powerful states tend to wield greater influence in international organizations. When states cannot or will not solve common international problems, nongovernmental organizations may intervene to try to do so.
In international relations, sovereignty is the ability of a state to chart its own path through the international system. In a system of sovereign states in which there is no overarching governing authority—no formal hierarchy—a condition of anarchy exists wherein each state seeks its own goals, which may be at odds with the goals of other sovereign states. This intrinsic push and pull for power and supremacy is at the heart of a system in which states push back on any organization or institution that seems to undermine its sovereignty.
Conflict is a natural part of a system in which multiple organizations vie for access to limited common resources and sovereign states may choose from many different courses of action. In complex situations where many factors affect state decisions about how to act in times of conflict, one way to understand how they arrive at those decisions is to use levels of analysis, breaking down the motivations, goals, and resources involved at the individual, state, and global level.
Realism is a theory of international relations that places states at the center of the system. In the realist view, states choose to enact policies focused on maintaining the security of their state. The states with the most power tend to have the most influence over other states in the system and tend to play the greatest role in global security. Unless there is one state with much more power than all the others, realists describe the maintenance of world order as requiring a balance of power among two or more great powers and their spheres of influence.
Liberalism, as a theory of international relations, places states as part of a larger system, working in concert with various other institutions to create an environment through which all people and states benefit. In the liberal view, states work together to achieve collective security. Constructivists see the system in which these interactions occur as an ever-changing one, the conditions of which are determined by how states see themselves, how they see other states, and how they see the system as a whole and by the norms of the system to which all states tend to adhere, which are usually heavily influenced by the most powerful states.
Just as the most powerful states tend to dominate the international system, the perspectives of those in power have tended to dominate the study of international relations. Critical theories of international relations, such as feminism and Marxism, push back against traditional points of view, bringing in the perspectives of underrepresented groups and questioning standard interpretations of the international system.