Liberalism holds that state preferences, rather than state capabilities, are the primary determinant of state behavior. Unlike realism where the state is seen as a unitary actor, liberalism allows for plurality in state actions. Thus, preferences will vary from state to state, depending on factors such as culture, economic system or government type. Liberalism also holds that interaction between states is not limited to the political (high politics), but also economic (low politics) whether through commercial firms, organizations or individuals. Thus, instead of an anarchic international system, there are plenty of opportunities for cooperation and broader notions of power, such as cultural capital (for example, the influence of American films leading to the popularity of American culture and creating a market for American exports worldwide). Another assumption is that absolute gains can be made through co-operation and interdependence - thus peace can be achieved.

Many different strands of liberalism have emerged; some include commercial liberalism, liberal institutionalism, idealism, and regime theory. Two forms of liberalism predominate, liberal institutionalism and idealism:

The former suggests that with the right factors, the international system provides opportunities for cooperation and interaction. Examples include the successful integration of Europe through the European Union or regional blocs and economic agreements such as ASEAN or NAFTA. Ramifications of this view are that if states cannot cooperate, they ought to be curbed, whether through economic sanctions or military action. For example, before the invasion of Iraq by the United States and United Kingdom in 2003, the governments' claims that Iraq possessed weapons of mass destruction could be seen as claims that Iraq is a bad state that needs to be curbed rather than an outright danger to American or European security. Thus, the invasion could be seen as curbing a bad state under liberal internationalism. A variant is Neo-liberal institutionalism (USA) which shifts back to a state-centric approach, but allows for pluralism through identifying and recognizing different actors, processes and structures.

The latter holds a view to promote a more peaceful world order through international organizations or IGOs; for example, through the United Nations (UN).

While liberalism increases the scope of study, it makes no attempt to question the status quo. It holds international institutions as benevolent forces - when in fact, they may act in pursuit of rational self-interest which may be at odds with those for peace.

Realists argue that liberalist arguments can be grounded in realism - and raw economic and military power still trumps cultural and other broader notions of power.

This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Liberal international relations theory".