《国际政治经济学》文献资料（International Political Economy and National Security）Power or Plenty Economic Interests, Security Concerns, and American

International Studies Quarterly (2008)52,737-758 Power or Plenty?Economic Interests, Security Concerns,and American Intervention BENJAMIN O.FORDHAM Binghamton University (SUNY) This paper evaluates the effect of economic interests and security con- cerns on American intervention in civil and international conflict.Gener- alizations about the relative importance of these considerations have played critical role in the historiography of American foreign relations. Although statistical analysis is well suited for evaluating such generaliza- tions,quantitative researchers have devoted relatively little attention to the issue.Existing large-n research has generally found that security con- cerns matter more.but has not considered how the economic and secu- rity concerns thought to affect intervention might also influence each other.These subsidiary relationships complicate efforts to assess the rela- tive importance of these two influences on intervention.Evidence con- cerning intervention in international crises and civil wars indicates that, while alliance commitments and rival behavior have a greater immediate impact on American intervention,exports have an important indirect effect by shaping alliance commitments in the long run. The Correlates of War Project records 2,007 disputes between states during the 20th century,129 of which escalated to war.There were also 35 wars between states and non-state entities outside their borders as well as 141 civil wars.Over the same period,there were also many other incidents of violence that were con- sequential for world politics but not recorded in the most frequently used data sets.In spite of the fact that the American role in world politics steadily expanded over the course of the century,the United States intervened in rela- tively few of these international conflicts.What explains American decisions about whether or not to become involved? This is one of the most important questions facing scholars of American for- eign policy.Answers illuminate policy makers'perceptions of national interest, and may thus help explain decisions about a wider range of foreign policy ques- tions.This article will focus on the relationship between two of the most impor- tant sources of explanation for American intervention:security concerns and economic interests.Although economic and security concerns are often posed as competing alternatives,most observers would probably concede that both matter. The question here is what role each plays in the process leading to intervention. Author's note:I would like to thank Michelle Benson,David H.Clark,Michael Colaresi,Patrick Regan,Elizabeth Saunders,and participants in the World Politics workshop at Binghamton University for their comments and sug gestions on carlier versions of this paper,as well as Viner (1948)for assistance with the title of this work.Any remaining errors are my responsibility.The data used in this article can be obtained from the author at(http:// bingweb.binghamton.edu/-bfordham/),or from the International Studies Quarterly Dataverse Network page at (http://dvn.iq.harvard.edu/dvn/). 2008 Intemational Studies Association

Power or Plenty? Economic Interests, Security Concerns, and American Intervention Benjamin O. Fordham Binghamton University (SUNY) This paper evaluates the effect of economic interests and security con￾cerns on American intervention in civil and international conflict. Gener￾alizations about the relative importance of these considerations have played critical role in the historiography of American foreign relations. Although statistical analysis is well suited for evaluating such generaliza￾tions, quantitative researchers have devoted relatively little attention to the issue. Existing large-n research has generally found that security con￾cerns matter more, but has not considered how the economic and secu￾rity concerns thought to affect intervention might also influence each other. These subsidiary relationships complicate efforts to assess the rela￾tive importance of these two influences on intervention. Evidence con￾cerning intervention in international crises and civil wars indicates that, while alliance commitments and rival behavior have a greater immediate impact on American intervention, exports have an important indirect effect by shaping alliance commitments in the long run. The Correlates of War Project records 2,007 disputes between states during the 20th century, 129 of which escalated to war. There were also 35 wars between states and non-state entities outside their borders as well as 141 civil wars. Over the same period, there were also many other incidents of violence that were con￾sequential for world politics but not recorded in the most frequently used data sets. In spite of the fact that the American role in world politics steadily expanded over the course of the century, the United States intervened in rela￾tively few of these international conflicts. What explains American decisions about whether or not to become involved? This is one of the most important questions facing scholars of American for￾eign policy. Answers illuminate policy makers’ perceptions of national interest, and may thus help explain decisions about a wider range of foreign policy ques￾tions. This article will focus on the relationship between two of the most impor￾tant sources of explanation for American intervention: security concerns and economic interests. Although economic and security concerns are often posed as competing alternatives, most observers would probably concede that both matter. The question here is what role each plays in the process leading to intervention. Author’s note: I would like to thank Michelle Benson, David H. Clark, Michael Colaresi, Patrick Regan, Elizabeth Saunders, and participants in the World Politics workshop at Binghamton University for their comments and sug￾gestions on earlier versions of this paper, as well as Viner (1948) for assistance with the title of this work. Any remaining errors are my responsibility. The data used in this article can be obtained from the author at (http:// bingweb.binghamton.edu/~bfordham/), or from the International Studies Quarterly Dataverse Network page at (http://dvn.iq.harvard.edu/dvn/). 2008 International Studies Association International Studies Quarterly (2008) 52, 737–758

738 Power or Plenty? The evidence considered here suggests that security concerns about the welfare of allies and the actions of rivals have a greater immediate impact on interven- tion decisions,but that economic interests also have important long-run indirect effects by shaping the things that get defined as security interests.The United States has been more likely to extend security guarantees to important trading partners than to less economically significant states.The process this evidence implies is one in which intervention decisions are made on the basis of security concerns rather than economic interests,just as decision makers typically claim they do.However,economic relationships shape these security interests over long periods of time in ways that may escape the attention of decision makers preoccu- pied with ongoing events. This article proceeds in four parts.The first reviews debates among historians and political scientists about the role of economic and security concerns in American foreign policy.The second sets out a research design for testing the influence of these two sources of explanation as well as the relationship between them.The third section presents the empirical results.A final section summa- rizes and concludes. Economic and Security Interests in Intervention Decisions What is the role of economic and security concerns in American decisions about intervention?Surprisingly,this question has received much greater attention from historians,who are typically less concerned about such broad patterns across space and time,than from political scientists,for whom such patterns are a central preoccupation.This section will first examine the way these two sets of researchers have addressed this question,then consider how each fits into the causal process leading to intervention. Historians,Political Scientists,and the Role of Economic and Security Concerns The relative importance of economic interests and security concerns has been a major bone of contention among historians of American foreign relations.Con- troversies among historians have generally focused on specific historical cases, but they also reflect broader theoretical differences about the forces that have shaped American foreign policy priorities.A political scientist (though probably not a historian)would say that these controversies concern competing models of the policymaking process.The debate over these models has often had an ideo- logical edge because of what they suggest about whose interests American for- eign policy has typically served.As the historian Emily Rosenberg(1993,37)has put it,"interpretations that stressed economics tended to be joined to radical critiques of American foreign policy and of America itself."Efforts to protect economic interests nearly always generate winners and losers in American society, while security is a public good that all Americans can enjoy. Models of the policy-making process play a different role in historical accounts of American foreign policy than in most political science research.Political scien- tists typically begin with an explicit model and then seek to test it empirically.By contrast,historians usually present a narrative account of the specific historical process that interests them without an explicit model.These narratives often incorporate material that is not relevant to a social-scientific test of the theoreti- cal model implicit in the work but that provides greater descriptive detail about what actually happened.The fact that historians'theoretical models of the for- eign policy process are implicit does not mean they are unimportant.Some theo- retical account of the underlying historical process is necessary to suggest relevant sources for research,to make connections among disparate pieces of evidence,and to fill in the gaps where the sources are silent

The evidence considered here suggests that security concerns about the welfare of allies and the actions of rivals have a greater immediate impact on interven￾tion decisions, but that economic interests also have important long-run indirect effects by shaping the things that get defined as security interests. The United States has been more likely to extend security guarantees to important trading partners than to less economically significant states. The process this evidence implies is one in which intervention decisions are made on the basis of security concerns rather than economic interests, just as decision makers typically claim they do. However, economic relationships shape these security interests over long periods of time in ways that may escape the attention of decision makers preoccu￾pied with ongoing events. This article proceeds in four parts. The first reviews debates among historians and political scientists about the role of economic and security concerns in American foreign policy. The second sets out a research design for testing the influence of these two sources of explanation as well as the relationship between them. The third section presents the empirical results. A final section summa￾rizes and concludes. Economic and Security Interests in Intervention Decisions What is the role of economic and security concerns in American decisions about intervention? Surprisingly, this question has received much greater attention from historians, who are typically less concerned about such broad patterns across space and time, than from political scientists, for whom such patterns are a central preoccupation. This section will first examine the way these two sets of researchers have addressed this question, then consider how each fits into the causal process leading to intervention. Historians, Political Scientists, and the Role of Economic and Security Concerns The relative importance of economic interests and security concerns has been a major bone of contention among historians of American foreign relations. Con￾troversies among historians have generally focused on specific historical cases, but they also reflect broader theoretical differences about the forces that have shaped American foreign policy priorities. A political scientist (though probably not a historian) would say that these controversies concern competing models of the policymaking process. The debate over these models has often had an ideo￾logical edge because of what they suggest about whose interests American for￾eign policy has typically served. As the historian Emily Rosenberg (1993, 37) has put it, ‘‘interpretations that stressed economics tended to be joined to radical critiques of American foreign policy and of America itself.’’ Efforts to protect economic interests nearly always generate winners and losers in American society, while security is a public good that all Americans can enjoy. Models of the policy-making process play a different role in historical accounts of American foreign policy than in most political science research. Political scien￾tists typically begin with an explicit model and then seek to test it empirically. By contrast, historians usually present a narrative account of the specific historical process that interests them without an explicit model. These narratives often incorporate material that is not relevant to a social-scientific test of the theoreti￾cal model implicit in the work but that provides greater descriptive detail about what actually happened. The fact that historians’ theoretical models of the for￾eign policy process are implicit does not mean they are unimportant. Some theo￾retical account of the underlying historical process is necessary to suggest relevant sources for research, to make connections among disparate pieces of evidence, and to fill in the gaps where the sources are silent. 738 Power or Plenty?

BENJAMIN O.FORDHAM 739 The model implied by historians who stress security concerns strongly resem- bles the one commonly advanced by realists in the international relations litera- ture.It suggests a plausible narrative of the way American policy makers have made decisions about intervention.American leaders,like the leaders of all states,must ensure the physical safety of Americans from foreign attack as well as the political sovereignty and territorial integrity of the American state in a condi- tion of international anarchy.This task has always been far easier than that con- fronting the leaders of states not fortunate enough to be surrounded by large oceans and weaker neighbors.For most of American history,these circumstances provided Americans with what Woodward(1960)aptly labeled "free security." As technology eroded the defensive value of the Atlantic and Pacific Oceans dur- ing the 20th century,American policy makers were forced to adopt a more activ- ist foreign policy in order to provide the same level of security.Entanglement in war and conflict in Europe and Asia became more difficult to avoid,and eventu- ally the United States found itself playing a leading role in alliance systems and other security arrangements all over the globe.Narratives informed by this broad understanding of American foreign policy tend to focus on policy makers'evolv- ing perceptions of international conditions. Historians stressing the importance of economic interests in shaping American foreign policy begin with a different argument about the priorities of American leaders.They treat American leaders'claims about national security skeptically. The best policy for insuring American security has been unclear and highly con- tested in important historical cases.For this reason,security concerns provide a weak basis for explaining American choices about intervention.These historians focus instead on the interests of the political coalitions backing particular Ameri- can leaders,constructing an alternative explanation for the increasing global activism of the United States during the 20th century.Broadly summarized,the story is that the American economy led to increasing demands for the protection of important overseas trading partners and investment sites,and a concomitant increase in the capacity of the American state to satisfy these demands.Historical narratives arising from this perspective tend to explain policy in terms of politi- cal conflict among domestic factions with competing interests. Even though theoretical arguments about the role of economic and security concerns are rarely stated explicitly,their influence is not difficult to discern in the historiography of American foreign relations.During the 1920s and 1930s,the debate over the reasons for American intervention in World War I turned on the question of economic motives (Cohen 1967;Fordham 2007)."Revisionist''histori- ans rejected the Wilson administration's reasons for American entry,arguing instead that the large American stake in wartime exports to the Allied powers heav- ily influenced the decision to intervene on their side in 1917 (e.g.,Beard 1936; Grattan 1929;Tansill 1938).The economic importance of this trade led the Wilson administration to take a hard line on German submarine warfare.This hard line ultimately led to intervention.Many other historians rejected the revisionist claim about the role of economic interests.They argued instead that security considerations-including anger over American loss of life due to the sub- marine campaign,fears about the consequences of a German victory,and national prestige were largely independent of trade with the Allies and played a more important role in the decision to intervene (e.g.,May 1959;Seymour [1935]1967; Smith 1965).The approach of World War II politicized this debate.Advocates of non-intervention adopted many elements of the revisionist argument in their suc- cessful legislative effort to restrict trade and lending to belligerent states.Many prominent revisionist historians,such as Charles Beard,supported them. After World War II,a new,more general controversy arose over the role of economic interests in American intervention.William A.Williams (1959)influen- tially argued that the demands of commercial expansion had driven American

The model implied by historians who stress security concerns strongly resem￾bles the one commonly advanced by realists in the international relations litera￾ture. It suggests a plausible narrative of the way American policy makers have made decisions about intervention. American leaders, like the leaders of all states, must ensure the physical safety of Americans from foreign attack as well as the political sovereignty and territorial integrity of the American state in a condi￾tion of international anarchy. This task has always been far easier than that con￾fronting the leaders of states not fortunate enough to be surrounded by large oceans and weaker neighbors. For most of American history, these circumstances provided Americans with what Woodward (1960) aptly labeled ‘‘free security.’’ As technology eroded the defensive value of the Atlantic and Pacific Oceans dur￾ing the 20th century, American policy makers were forced to adopt a more activ￾ist foreign policy in order to provide the same level of security. Entanglement in war and conflict in Europe and Asia became more difficult to avoid, and eventu￾ally the United States found itself playing a leading role in alliance systems and other security arrangements all over the globe. Narratives informed by this broad understanding of American foreign policy tend to focus on policy makers’ evolv￾ing perceptions of international conditions. Historians stressing the importance of economic interests in shaping American foreign policy begin with a different argument about the priorities of American leaders. They treat American leaders’ claims about national security skeptically. The best policy for insuring American security has been unclear and highly con￾tested in important historical cases. For this reason, security concerns provide a weak basis for explaining American choices about intervention. These historians focus instead on the interests of the political coalitions backing particular Ameri￾can leaders, constructing an alternative explanation for the increasing global activism of the United States during the 20th century. Broadly summarized, the story is that the American economy led to increasing demands for the protection of important overseas trading partners and investment sites, and a concomitant increase in the capacity of the American state to satisfy these demands. Historical narratives arising from this perspective tend to explain policy in terms of politi￾cal conflict among domestic factions with competing interests. Even though theoretical arguments about the role of economic and security concerns are rarely stated explicitly, their influence is not difficult to discern in the historiography of American foreign relations. During the 1920s and 1930s, the debate over the reasons for American intervention in World War I turned on the question of economic motives (Cohen 1967; Fordham 2007). ‘‘Revisionist’’ histori￾ans rejected the Wilson administration’s reasons for American entry, arguing instead that the large American stake in wartime exports to the Allied powers heav￾ily influenced the decision to intervene on their side in 1917 (e.g., Beard 1936; Grattan 1929; Tansill 1938). The economic importance of this trade led the Wilson administration to take a hard line on German submarine warfare. This hard line ultimately led to intervention. Many other historians rejected the revisionist claim about the role of economic interests. They argued instead that security considerations—including anger over American loss of life due to the sub￾marine campaign, fears about the consequences of a German victory, and national prestige were largely independent of trade with the Allies and played a more important role in the decision to intervene (e.g., May 1959; Seymour [1935] 1967; Smith 1965). The approach of World War II politicized this debate. Advocates of non-intervention adopted many elements of the revisionist argument in their suc￾cessful legislative effort to restrict trade and lending to belligerent states. Many prominent revisionist historians, such as Charles Beard, supported them. After World War II, a new, more general controversy arose over the role of economic interests in American intervention. William A. Williams (1959) influen￾tially argued that the demands of commercial expansion had driven American Benjamin O. Fordham 739

740 Power or Plenty? involvement in less developed areas of the world since the 1890s.Other histori- cal accounts of American foreign policy followed Williams'example,stressing the role of economic interests in spurring the overseas activity of the American state (e.g.,LaFeber 1963;McCormick 1967).This group of historians-also commonly referred to as "revisionists,"although few discussed American involvement in World War I-were also skeptical of the Cold War security concerns offered to justify most postwar interventions (e.g.,Kolko and Kolko 1972;LaFeber1967). Many other historians objected to interpretations stressing economic interests, offering accounts that emphasized security concerns over the spread of Soviet power.They held that the revisionists were unduly critical of American policy makers'motives,and that the security concerns these policy makers had cited were not mere window-dressing for underlying economic interests (e.g.,Gaddis 1972;Tucker 1971).As had been the case with interpretations of American inter- vention in World War I,the scholarly debate's resonance with contemporary policy issues-in this case,the Vietnam War-politicized it.Historiographical controversy over the role of economic and security concerns in Cold War foreign policy did not entirely lose its political edge even after the Cold War came to an end (e.g.,Cumings 1993;Gaddis 1996;Schrecker 2004). Political scientists are typically more interested in theoretical generalization than are historians,so it is somewhat surprising that the relative importance of economic and security concerns in American intervention has received less atten- tion from them.Case study research that most resembles (and often relies upon) the work of historians has paid the most attention to the issue.The divergent conclusions about the role of economic interests mirror those found among historians.While some have presented evidence that these interests have played a crucial role in some intervention decisions (e.g.,Cox 1994;Gibbs 1990; McKeown 2000),others accord greater importance to security concerns derived from state decision makers'conceptions of the national interest (e.g.,Krasner 1978;Lake1988). The relative importance of economic and security interests in American for- eign policy has received much less attention from quantitative researchers.What there is tends to support the importance of security concerns relative to eco- nomic interests.Some early studies found evidence that economic interests influ- enced decisions about intervention (e.g.,Odell 1974;Rosen 1974).However, subsequent work has generally found greater support for security concerns than for economic interests (e.g.,Meernik 1994;Pearson and Baumann 1977;Yoon 1997).Perhaps reflecting these findings,the considerable body of recent research on civil war intervention has set economic concerns aside and focused on other explanations for intervention,such as the nature of the conflict or stra- tegic interaction among potential interveners (e.g.,Findley and Teo 2006;Regan 1998,2000).Indeed,most recent quantitative analyses of intervention do not include economic variables at all. The neglect of the question of economic and security interests in quantitative research on intervention is unfortunate.This approach is especially well suited for answering questions about the relative importance of these concerns across large numbers of historical cases.These are precisely the kinds of generalizations that have sparked so much controversy among historians of American foreign relations.Even though most scholars engaged in quantitative empirical research understandably prefer to study theoretical arguments that apply to more than just the U.S.case,patterns confined to smaller slices of space and time still deserve attention.Given the nation's enormous role in the contemporary world, understanding the sources of American behavior is not simply a parochial con- cern.A more general explanation also accounting for the behavior of many other states might be preferable,but is not available.In its absence,testing more

involvement in less developed areas of the world since the 1890s. Other histori￾cal accounts of American foreign policy followed Williams’ example, stressing the role of economic interests in spurring the overseas activity of the American state (e.g., LaFeber 1963; McCormick 1967). This group of historians—also commonly referred to as ‘‘revisionists,’’ although few discussed American involvement in World War I—were also skeptical of the Cold War security concerns offered to justify most postwar interventions (e.g., Kolko and Kolko 1972; LaFeber 1967). Many other historians objected to interpretations stressing economic interests, offering accounts that emphasized security concerns over the spread of Soviet power. They held that the revisionists were unduly critical of American policy makers’ motives, and that the security concerns these policy makers had cited were not mere window-dressing for underlying economic interests (e.g., Gaddis 1972; Tucker 1971). As had been the case with interpretations of American inter￾vention in World War I, the scholarly debate’s resonance with contemporary policy issues—in this case, the Vietnam War—politicized it. Historiographical controversy over the role of economic and security concerns in Cold War foreign policy did not entirely lose its political edge even after the Cold War came to an end (e.g., Cumings 1993; Gaddis 1996; Schrecker 2004). Political scientists are typically more interested in theoretical generalization than are historians, so it is somewhat surprising that the relative importance of economic and security concerns in American intervention has received less atten￾tion from them. Case study research that most resembles (and often relies upon) the work of historians has paid the most attention to the issue. The divergent conclusions about the role of economic interests mirror those found among historians. While some have presented evidence that these interests have played a crucial role in some intervention decisions (e.g., Cox 1994; Gibbs 1990; McKeown 2000), others accord greater importance to security concerns derived from state decision makers’ conceptions of the national interest (e.g., Krasner 1978; Lake 1988). The relative importance of economic and security interests in American for￾eign policy has received much less attention from quantitative researchers. What there is tends to support the importance of security concerns relative to eco￾nomic interests. Some early studies found evidence that economic interests influ￾enced decisions about intervention (e.g., Odell 1974; Rosen 1974). However, subsequent work has generally found greater support for security concerns than for economic interests (e.g., Meernik 1994; Pearson and Baumann 1977; Yoon 1997). Perhaps reflecting these findings, the considerable body of recent research on civil war intervention has set economic concerns aside and focused on other explanations for intervention, such as the nature of the conflict or stra￾tegic interaction among potential interveners (e.g., Findley and Teo 2006; Regan 1998, 2000). Indeed, most recent quantitative analyses of intervention do not include economic variables at all. The neglect of the question of economic and security interests in quantitative research on intervention is unfortunate. This approach is especially well suited for answering questions about the relative importance of these concerns across large numbers of historical cases. These are precisely the kinds of generalizations that have sparked so much controversy among historians of American foreign relations. Even though most scholars engaged in quantitative empirical research understandably prefer to study theoretical arguments that apply to more than just the U.S. case, patterns confined to smaller slices of space and time still deserve attention. Given the nation’s enormous role in the contemporary world, understanding the sources of American behavior is not simply a parochial con￾cern. A more general explanation also accounting for the behavior of many other states might be preferable, but is not available. In its absence, testing more 740 Power or Plenty?

BENJAMIN O.FORDHAM 741 limited theoretical generalizations is useful,especially when doing so can advance a debate in such a closely allied field of study. Thinking Through the Role of Economic and Security Interests One of the striking features of the debate over the relative importance of eco- nomic interests and security concerns is that scholars rarely argue that either set of considerations is entirely irrelevant to policy choice.Even those who strongly emphasize one source of explanation over the other usually acknowledge that many factors contributed to intervention decisions.For example,in spite of the stark differences between revisionist historians of American intervention in World War I and their critics,members of both camps commonly acknowledged the influence of security concerns as well as economic interests in their narra- tives (Fordham 2007,283-84).For most scholars,interpreting the role of eco- nomic and security concerns is a matter of emphasis. The likelihood that both considerations may make a difference complicates efforts to explain intervention in ways that are not always appreciated in the exist- ing research.Most efforts to assess the relative importance of economic and secu- rity concerns have implicitly assumed that these two sources of explanation do not cause one another.This assumption is clearest in the quantitative political sci- ence literature,where the most common approach has been to regress decisions about intervention on indicators of economic and security concerns without pay- ing much attention to the relationships among the independent variables.The assumption is less visible but equally important in qualitative research on inter- vention.Historical researchers usually focus on archival evidence concerning the decision-making process.The assumption that economic and security concerns are independent justifies the inference that,when security concerns dominate policy deliberations,economic interests are relatively unimportant. There are good reasons to suppose that security concerns and economic inter- ests are not causally unrelated,however.Economic interests may help define security concerns,or security-motivated polices could shape economic interests. The fact that the relationship might run in either direction is crucial for assess- ing the relative importance of these two sets of concerns and for discerning their roles in the causal process.Previous research has found evidence that bilateral trade is greater among allies (Gowa and Mansfield 1993,2004;Long 2003;Mans- field and Bronson 1997).Gowa and Mansfield(1993)argue that trade generates security externalities by strengthening the economies,and thus the military potential,of the states involved.They suggest that states seek to manipulate these externalities by encouraging trade with their allies and limiting it with their potential enemies.If trade indeed follows the flag in this way,then part of trade's apparent effect on intervention decisions would really be due to the indi- rect influence of the security commitments on trading patterns. On the other hand,the causal arrow might point in the opposite direction: strong trade relations or other economic interests might make the formation of an alliance more likely.Policy makers should care about the security of economi- cally important markets or sites for investment because the benefits they draw from these economic relationships depend on it.This line of argument follows from liberal claims about the conflict-reducing effects of international commerce on trading partners (e.g.,Oneal and Russett 1997;Polachek 1980).The source of this effect is state leaders'concern about the loss of income to their citizens due to conflict's disruptive effects on trade.The same logic suggests that,to the extent that income from trade depends on the security and stability of a state's trading partners,states should be more likely to make costly commitments to assist those states.Major powers like the United States are especially likely to pro- tect their trading partners because they have the capacity to do so,something

limited theoretical generalizations is useful, especially when doing so can advance a debate in such a closely allied field of study. Thinking Through the Role of Economic and Security Interests One of the striking features of the debate over the relative importance of eco￾nomic interests and security concerns is that scholars rarely argue that either set of considerations is entirely irrelevant to policy choice. Even those who strongly emphasize one source of explanation over the other usually acknowledge that many factors contributed to intervention decisions. For example, in spite of the stark differences between revisionist historians of American intervention in World War I and their critics, members of both camps commonly acknowledged the influence of security concerns as well as economic interests in their narra￾tives (Fordham 2007, 283–84). For most scholars, interpreting the role of eco￾nomic and security concerns is a matter of emphasis. The likelihood that both considerations may make a difference complicates efforts to explain intervention in ways that are not always appreciated in the exist￾ing research. Most efforts to assess the relative importance of economic and secu￾rity concerns have implicitly assumed that these two sources of explanation do not cause one another. This assumption is clearest in the quantitative political sci￾ence literature, where the most common approach has been to regress decisions about intervention on indicators of economic and security concerns without pay￾ing much attention to the relationships among the independent variables. The assumption is less visible but equally important in qualitative research on inter￾vention. Historical researchers usually focus on archival evidence concerning the decision-making process. The assumption that economic and security concerns are independent justifies the inference that, when security concerns dominate policy deliberations, economic interests are relatively unimportant. There are good reasons to suppose that security concerns and economic inter￾ests are not causally unrelated, however. Economic interests may help define security concerns, or security-motivated polices could shape economic interests. The fact that the relationship might run in either direction is crucial for assess￾ing the relative importance of these two sets of concerns and for discerning their roles in the causal process. Previous research has found evidence that bilateral trade is greater among allies (Gowa and Mansfield 1993, 2004; Long 2003; Mans- field and Bronson 1997). Gowa and Mansfield (1993) argue that trade generates security externalities by strengthening the economies, and thus the military potential, of the states involved. They suggest that states seek to manipulate these externalities by encouraging trade with their allies and limiting it with their potential enemies. If trade indeed follows the flag in this way, then part of trade’s apparent effect on intervention decisions would really be due to the indi￾rect influence of the security commitments on trading patterns. On the other hand, the causal arrow might point in the opposite direction: strong trade relations or other economic interests might make the formation of an alliance more likely. Policy makers should care about the security of economi￾cally important markets or sites for investment because the benefits they draw from these economic relationships depend on it. This line of argument follows from liberal claims about the conflict-reducing effects of international commerce on trading partners (e.g., Oneal and Russett 1997; Polachek 1980). The source of this effect is state leaders’ concern about the loss of income to their citizens due to conflict’s disruptive effects on trade. The same logic suggests that, to the extent that income from trade depends on the security and stability of a state’s trading partners, states should be more likely to make costly commitments to assist those states. Major powers like the United States are especially likely to pro￾tect their trading partners because they have the capacity to do so, something Benjamin O. Fordham 741