Liberal international relations theory holds that societies are capable of overcoming conflict through cooperative behavior and the construction of institutions which mitigate the anarchic nature of geopolitics. Adherents of this school, which is also called "liberal internationalism" or "liberal institutionalism," often attribute conflict to selfish national interests and weak national institutions which can be overcome by the work of NGOs and non-state actors, international and transnational organizations, and vectors for interstate interdependence (such as trade and collective security agreements).
The "realist" school of IR theory emphasizes the state as the sole international actor, and one which avoids or enters conflict to serve its particular self-interest. Classical realism holds that material interests and power drive state leaders, whereas neo-realists argue that security (avoidance of conflict) and longer-term interests play a role in preference and decision-making. This school traditionally understands some notion of the inevitability of rivalry and conflict and diminishes the notion that human nature can be overcome through agreements or institutions.