Liberal international relations (IR) theory is related to, but distinct from, the Utopianism of the interwar period. The utopians believed that war could be eliminated either by perfecting man or by perfecting government. The roots of modern liberal international relations theory can be traced back farther than utopianism to Immanuel Kant’s essay “To Perpetual Peace” (1795) (and arguably farther; see Kant 2003, cited under Immanuel Kant). In that essay Kant provided three “definitive conditions” for perpetual peace, each of which became a dominant strain of post–World War II liberal IR theory. Neoliberal Institutionalism (also called “neoliberalism” or “institutional liberalism”) emphasizes the importance of international institutions (Kant’s “federation of free states”) in maintaining peace. Commercial Liberalism emphasizes the importance of economic interdependence and free trade (Kant’s “universal hospitality”) in maintaining peace. Democratic Peace Theory argues that democracies rarely, if ever, go to war with each other, and thus an executive accountable to the people or the parliament is important to maintain peace (Kant’s call for all states to have “republican constitutions”). There are other forms of liberal IR theory that are not explicitly dealt with in this article, such as functionalism and neofunctionalism, for example. For the purposes of a broad overview of the theory, only the predominant strains of liberal IR theory are included. Earlier generations of scholars refer to liberalism as “idealism.” More recent scholarship uses “idealism” to refer to “utopianism” or even “constructivism.” However, all postwar liberal theories share a few basic concepts that allow them to be called “liberal”: (1) states are the primary actors in the international system, but they are not unitary—domestic politics matters; (2) there are factors beyond capabilities that constrain state behavior; and (3) states’ interests are multiple and changing. The key concepts found in liberal theory are absolute gains, international institutions, free trade, and democracy. International Law is also important in liberal IR theory as it is seen as forming a major constraint on state behavior. Particular international institutions are also important in the development of liberal IR theory, but they are not explicitly dealt with in this article. Liberal IR theory is a particularly Western-focused theory that deals with the advantages, limitations, and exportability of typically Western forms of government. Thus, American and English sources dominate this article. It could be argued that the “English school” belongs here, but the placement of the English school in solely a realist, liberal, or constructivist framework could be considered quite controversial, as its locus within IR theory is contested. Therefore, the English school is dealt with in the “International Relations Theory” article, and more extensively in the “International Society” article.
Investigations of Kantian Cosmopolitanism: Evolution of the Species, Sovereignty and Hospitality
