2 WORLD POLITICS international wars with one another and the use or threat of force among them,even at low levels,has been rare.2 This view is incomplete, however,because it fails to recognize the pacific benefits of the other lib- eral elements of Kant's program for peace.Moreover,the term hides the vigorous theoretical controversy about the processes underlying this sep- arate peace-over whether democracy is really even its cause and over the degree to which the empirical phenomenon existed in other eras. These theoretical and empirical concerns are linked.If,for example, peaceful relations among democracies during the cold war era were simply a consequence of their shared security interests vis-a-vis the op- posing alliance system in a bipolar world,then their peacefulness would be spuriously related to the character of their regimes.The same con- clusion would result if the democratic peace could be attributed to the hegemonic power of the United States to suppress conflict among its allies or to East-West differences in preferences unrelated to underlying differences in regimes.3 One would not then expect to find a separate peace among democratic states in other periods evincing different pat- terns of interstate relations.We address these questions by reporting analyses covering 1885-1992,to show that peaceful relations among democracies existed throughout the twentieth century.4 Extending the historical domain also allows us to assess the effect of the changing character of the international system on interstate relations.5 2 By convention in the social science literature,war is defined as a conflict between two recognized sovereign members of the international system that results in at least one thousand battle deaths.The most complete data on militarized international disputes (MIDs),compiled by Stuart Bremer and his colleagues,are available at http://pss.la-psu.edu/MID_DATA.HTM.The democracy data we employ were compiled by Keith Jaggers and Ted Robert Gurr,"Tracking Democracy's Third Wave with the Polity III Data,"Journal of Peace Research 32,no.4(1995),available at http://iscre.colorado.cdu- /pub/datasets/polity3/politymay96.data.Both data sets are produced independently from the demo- cratic peace research program,and the initial codings,from the 1980s,precede it.Reviews of the program include Steve Chan,"In Search of Democratic Peace:Problems and Promise,"Mershon Inter- national Studies Review 41,no.1(1997);James Lee Ray,"Does Democracy Cause Peace?"Annual Review of Political Science 1(1997);and Bruce Russett and Harvey Starr,"From Democratic Peace to Kantian Peace:Democracy and Confict in the International System,"in Manus Midlarsky,ed.,Handboo ofWar Studies,2d ed.(Ann Arbor:University of Michigan Press,forthcoming). 3 Henry Farber and Joanne Gowa,"Common Interests or Common Polities?"Journal of Politics 57,no. 2(1997);Gowa,Ballots and Bullets:The Elusive Democratic Peace (Princeton:Princeton University Press, 1999);Douglas Lemke and William Reed,"Regime Types and Status Quo Evaluations,"International Interactions 22,no.2(1996);Erik Gartzke,"Kant We All Just Get Along?Opportunity,Willingness and the Origins of the Democratic Peace,"American Journal of Political Science 42,no.1 (1998). The MIDs data(fn.2)are unavailable after 1992,and data on dyadic trade are sparse and unreliable before 1885.In any event the further back one goes into the nineteenth century,the rarer are instances of democracy,intergovernmental organizations,and high levels of economic interdependence.The MIDs data include only disputes between recognized states and not,for example,extrasystemic(ie.,colonial) actions,covert operations,or domestic military interventions in support of a recognized government. s We will not here offer a new theory on why democracy produces peaceful relations.A recent state- ment is Bruce Bueno de Mesquita et al,An Institutional Explanation of the Democratic Peace," American Political Science Review 93,no.4 (1999).2 WORLD POLITICS international wars with one another and the use or threat of force among them, even at low levels, has been rare.2 This view is incomplete, however, because it fails to recognize the pacific benefits of the other lib eral elements of Kant s program for peace. Moreover, the term hides the vigorous theoretical controversy about the processes underlying this sep arate peace?over whether democracy is really even its cause and over the degree to which the empirical phenomenon existed in other eras. These theoretical and empirical concerns are linked. If, for example, peaceful relations among democracies during the cold war era were simply a consequence of their shared security interests vis-?-vis the op posing alliance system in a bipolar world, then their peacefulness would be spuriously related to the character of their regimes. The same con clusion would result if the democratic peace could be attributed to the hegemonic power of the United States to suppress conflict among its allies or to East-West differences in preferences unrelated to underlying differences in regimes.3 One would not then expect to find a separate peace among democratic states in other periods evincing different pat terns of interstate relations. We address these questions by reporting analyses covering 1885-1992, to show that peaceful relations among democracies existed throughout the twentieth century4 Extending the historical domain also allows us to assess the effect of the changing character of the international system on interstate relations.5 2 By convention in the social science literature, war is defined as a conflict between two recognized sovereign members of the international system that results in at least one thousand battle deaths. The most complete data on militarized international disputes (MIDs), compiled by Stuart Bremer and his colleagues, are available at http://pss.la.psu.edu/MID_DATA.HTM. The democracy data we employ were compiled by Keith Jaggers and Ted Robert Gurr, "Tracking Democracy's Third Wave with the Polity III Data,"Journalof* Peace Research 32, no. 4 (1995), available at http://isere.colorado.edu /pub/datasets/polity3/politymay96.data. Both data sets are produced independently from the demo cratic peace research program, and the initial codings, from the 1980s, precede it. Reviews of the program include Steve Chan, "In Search of Democratic Peace: Problems and Promise," Mershon Inter national Studies Review 41, no. 1 (1997); James Lee Ray, "Does Democracy Cause Peace?" Annual Review of Political Science 1 (1997); and Bruce Russett and Harvey Starr, "From Democratic Peace to Kantian Peace: Democracy and Conflict in the International System," in Manus Midlarsky, ed., Handbook of War Studies, 2d ed. (Ann Arbor: University of Michigan Press, forthcoming). 3 Henry F?rber and Joanne Gowa, "Common Interests or Common Polities?" Journal of Politics 57, no. 2 (1997); Gowa, Ballots and Bullets: The Elusive Democratic Peace (Princeton: Princeton University Press, 1999); Douglas Lemke and William Reed, "Regime Types and Status Quo Evaluations," International Interactions 22, no. 2 (1996); Erik Gartzke, "Kant We All Just Get Along? Opportunity, Willingness and the Origins of the Democratic Peace,"American JournalofPoliticalScience 42, no. 1 (1998). 4 The MIDs data (fn. 2) are unavailable after 1992, and data on dyadic trade are sparse and unreliable before 1885. In any event the further back one goes into the nineteenth century, the rarer are instances of democracy, intergovernmental organizations, and high levels of economic interdependence. The MIDs data include only disputes between recognized states and not, for example, extrasystemic (i.e., colonial) actions, covert operations, or domestic military interventions in support of a recognized government. 5 We will not here offer a new theory on why democracy produces peaceful relations. A recent state ment is Bruce Bueno de Mesquita et al., "An Institutional Explanation of the Democratic Peace," American Political Science Review 93, no. 4 (1999)