Liberal Theory of International Politics 515 tific sense cannot exist.Robert Keohane,an institutionalist sympathetic to liberal- ism,maintains that"in contrast to Marxism and Realism,Liberalism is not committed to ambitious and parsimonious structural theory."Michael Doyle,a pioneer in ana- lyzing the "democratic peace,"observes that liberal IR theory,unlike others,lacks "canonical"foundations.Mark Zacher and Richard Matthew,sympathetic liberals, assert that liberalism should be considered an "approach,"not a theory,since "its propositions cannot be...deduced from its assumptions."4 Accurate though this may be as a characterization of intellectual history and current theory,it is second- best social science. I seek to move beyond this unsatisfactory situation by proposing a set of core assumptions on which a general restatement of positive liberal IR theory can be grounded.In the first section of the article I argue that the basic liberal insight about the centrality of state-society relations to world politics can be restated in terms of three positive assumptions,concerning,respectively,the nature of fundamental so- cial actors,the state,and the international system. Drawing on these assumptions,I then elaborate three major variants of liberal theory-each grounded in a distinctive causal mechanism linking social preferences and state behavior.Ideational liberalism stresses the impact on state behavior of conflict and compatibility among collective social values or identities concerning the scope and nature of public goods provision.Commercial liberalism stresses the im- pact on state behavior of gains and losses to individuals and groups in society from transnational economic interchange.Republican liberalism stresses the impact on state behavior of varying forms of domestic representation and the resulting incen- tives for social groups to engage in rent seeking.5 Finally,I demonstrate that the identification of coherent theoretical assumptions is not simply an abstract and semantic matter.It has significant methodological,theo- retical,and empirical implications.The utility of a paradigmatic restatement should be evaluated on the basis of four criteria,each relevant to the empirical researcher: superior parsimony,coherence,empirical accuracy,and multicausal consistency First,a theoretical restatement should be general and parsimonious,demonstrat- ing that a limited number of microfoundational assumptions can link a broad range of previously unconnected theories and hypotheses.This restatement does so by show- ing how liberalism provides a general theory of IR linking apparently unrelated areas of inguiry.The theory outlined here applies equally to liberal and nonliberal states,economic and national security affairs,conflictual and nonconflictual situa- tions,and the behavior both of individual states ("foreign policy")and of aggrega- tions of states ("international relations").Liberal theory,moreover,explains impor- tant phenomena overlooked by alternative theories,including the substantive content of foreign policy,historical change,and the distinctiveness of interstate relations among modern Western states. 4.See Keohane 1990,166,172-73;Doyle 1986,1152;Zacher and Matthew 1992,2;Matthew and Zacher1995,107-11,117-20;Hoffmann1987,1995:and Nye1988. 5.For other such distinctions,see Keohane 1990;and Doyle 1983.Liberal Theory of International Politics 515 tific sense cannot exist. Robert Keohane, an institutionalist sympathetic to liberal￾ism, maintains that "in contrast to Marxism and Realism, Liberalism is not committed to ambitious and parsimonious structural theory." Michael Doyle, a pioneer in ana￾lyzing the "democratic peace," observes that liberal IR theory, unlike others, lacks "canonical" foundations. Mark Zacher and Richard Matthew, sympathetic liberals, assert that liberalism should be considered an "approach," not a theory, since "its propositions cannot be . . . deduced from its assumption^."^ Accurate though this may be as a characterization of intellectual history and current theory, it is second￾best social science. I seek to move beyond this unsatisfactory situation by proposing a set of core assumptions on which a general restatement of positive liberal IR theory can be grounded. In the first section of the article I argue that the basic liberal insight about the centrality of state-society relations to world politics can be restated in terms of three positive assumptions, concerning, respectively, the nature of fundamental so￾cial actors, the state, and the international system. Drawing on these assumptions, I then elaborate three major variants of liberal theory--each grounded in a distinctive causal mechanism linking social preferences and state behavior. Ideational liberalism stresses the impact on state behavior of conflict and compatibility among collective social values or identities concerning the scope and nature of public goods provision. Commercial liberalism stresses the im￾pact on state behavior of gains and losses to individuals and groups in society from transnational economic interchange. Republican liberalism stresses the impact on state behavior of varying forms of domestic representation and the resulting incen￾tives for social groups to engage in rent ~eeking.~ Finally, I demonstrate that the identification of coherent theoretical assumptions is not simply an abstract and semantic matter. It has significant methodological, theo￾retical, and empirical implications. The utility of a paradigmatic restatement should be evaluated on the basis of four criteria, each relevant to the empirical researcher: superior parsimony, coherence, empirical accuracy, and multicausal consistency. First, a theoretical restatement should be general and parsimonious, demonstrat￾ing that a limited number of microfoundational assumptions can link a broad range of previously unconnected theories and hypotheses. This restatement does so by show￾ing how liberalism provides a general theory of IR linking apparently unrelated areas of inquiry. The theory outlined here applies equally to liberal and nonliberal states, economic and national security affairs, conflictual and nonconflictual situa￾tions, and the behavior both of individual states ("foreign policy ") and of aggrega￾tions of states ("international relations"). Liberal theory, moreover, explains impor￾tant phenomena overlooked by alternative theories, including the substantive content of foreign policy, historical change, and the distinctiveness of interstate relations among modem Western states. 4. See Keohane 1990, 166, 172-73; Doyle 1986, 1152; Zacher and Matthew 1992, 2; Matthew and Zacher 1995, 107-1 1, 117-20; Hoffmann 1987, 1995; and Nye 1988. 5. For other such distinctions, see Keohane 1990; and Doyle 1983