This article reformulates liberal international relations (IR) theory
in nonideological and nonutopian form appropriate to empirical social
science. Liberal IR theory elaborates the basic insight that state-soc
iety relations-the relationship between governments and the domestic a
nd transnational social context in which they are embedded-are the mos
t fundamental determinant of state behavior in world politics. In the
liberal view state-society relations influence state behavior by shapi
ng ''national preferences'' - the fundamental social purposes that und
erlie state strategies-not, as realism argues, the configuration of na
tional capabilities and not, as institutionalist regime theory maintai
ns, the configuration of information and institutions. This article co
difies this basic liberal insight in the form of three core analytical
propositions, derives from these propositions three variants of liber
al theory, and demonstrates that the existence of a coherent liberal t
heory has significant theoretical, methodological, and empirical impli
cations. These implications include the existence of significant omitt
ed variable bias in recent realist and constructivist studies, and the
analytical priority of liberal theory, which emerges as the most fund
amental among major LR theories because it defines and explains the co
nditions under which realist and institutionalist, as well as construc
tivist, factors matter.