This entry is a subentry of Disciplinary Views Of War.
The study of war in the West goes back to the time of Thucydides, who averred that the cause of the Peloponnesian War was “the growth of Athenian power and the fear this caused in Sparta.” The founding of the modern discipline of international relations, however, did not occur until the end of World War I with the endowment of the world's first chair in International Politics at Aberystwyth, Wales. This institutionalization of the field was a result of Wilsonian thinking prevalent at the end of the war that through the use of reason and the spread of education the causes of war could be discovered and eliminated. The rise of Nazi Germany and militaristic Japan led to the collapse of the League of Nations and the emergence of a “realist” school, which criticized the “idealists” for failing to understand and use power. The credit for shifting the field of international relations from idealist advocacy to realist analysis is usually given to Hans J. Morgenthau's Politics Among Nations (1948).
Explanations that emphasize the shifts in power and the struggle for power are the hallmark of the realist school of international relations, which claims Thucydides, Machiavelli, Hobbes, and Carl Von Clausewitz as its forebears. Realists tend to see war as endemic and a natural occurrence with shifts in power often associated with the onset of war. In the contemporary period, Hans J. Morgenthau, Kenneth N. Waltz, and Robert Gilpin represent the most important thinkers of this school, but none of them has a precise explanation of war. Waltz sees the anarchic nature of the international system (the absence of some form of world governing structure) as a “permissive” cause of war, that is, there is nothing in the system to prevent states from resorting to war any time they choose. But what brings about war in any given instance is not specified. Gilpin comes closest to stipulating the conditions that lead to war by maintaining that the largest wars come about when a rising ascendent state challenges the dominant hegemony of the system. However, he sees this as only a necessary condition of war, which means that the sufficient conditions are unspecified. Likewise, his explanation leaves unexplained the vast number of interstate wars that do not involve the two strongest states in the system.
Realist work often tends to support its explanations with argumentation and historical analysis. In the late 1950s and early 1960s, the behavioral movement in political science criticized this approach because it tended to “ransack history” by looking for cases that would support its explanations while ignoring evidence that contradicted them. These “behavioralists” wanted to apply the scientific method to the search for the causes of war. They were inspired by the early work of Lewis F. Richardson, who pioneered the use of mathematical models and statistical data analysis to study war and by Quincy Wright, who employed a broad interdisciplinary approach in his seminal study on the causes of war. J. David Singer founded the Correlates of War project and, building on the efforts of Richardson and Wright, began collecting data on war, capability, and alliances in the hopes that empirical research would be able to delineate patterns as a step toward constructing scientific explanations. A number of other researchers developed and tested scientific explanations of war focusing on capability. These included Organski and Kugler's power transition, Modelski and Thompson's long cycle, Charles Doran's power cycle, and Bueno de Mesquita's expected utility models (see Midlarsky, 2000).
Empirical research has produced a number of findings that have not been supportive of simple realist explanations, particularly the notion that a balance of power is associated with peace, or that a disruption of it is associated with war. Singer, Bremer, and Stuckey (in Singer, 1979) find that parity (relative balance) in the international system is associated with a low magnitude of war in the nineteenth century, but with a high magnitude of war in the twentieth century. Neither parity nor a preponderance of power in the system is associated with the complete absence of war. A follow‐up study by Bueno de Mesquita (1981) found no relationship between capability distribution and periods of war or peace in either century. The evidence overall implies that while capability distributions may in certain contexts be associated with wars of high or low magnitude, no particular type of capability distribution is associated with peace. One of the reasons for this, as Bueno de Mesquita points out, is that a balance of power usually implies a fifty‐fifty chance of winning a war, and thus will only inhibit risk‐averse leaders. Later work by Buena de Mesquita and Lalman demonstrates the importance of supplementing power calculations with an analysis of domestic political factors in order to explain the decision to go to war.
Realists often assert that alliance making, because it is usually a result of attempts to balance power, can be a force for peace. The research of Jack Levy (1981) raises questions about this claim since he finds that from 1495 to 1975, with the exception of the nineteenth century, most great power alliances (56 percent to 100 percent) have been followed by war within five years. An even more pernicious effect of alliances uncovered by researchers focusing on the post‐1815 period is that once war breaks out, alliances can act as a contagion mechanism to expand war.
Among the major states, war does not usually break out with the first crisis. Leng (1983) and Brecher and Wilkenfeld (1997) show that as states go from one crisis to the next, the probability of war goes way up. To date, empirical research has found that the crises that escalate tend to have the following characteristics: they are triggered by physical threats to vital issues; they are one in a series of repeated confrontations, with realpolitik tactics becoming more coercive; a hostile interaction spiral emerges; and there is an ongoing arms race.
Of these findings, the most controversial is that linking arms races and crisis escalation, first enunciated by Michael Wallace. Paul Diehl (1983) has questioned the validity and reliability of Wallace's (1982) arms race index and was unable to replicate it. Nevertheless, Diehl's own research shows a relationship between escalation to war and some sort of measure of military buildup and defense burden. Subsequent research by Susan Semple (1997), using Diehl's index shows that, except for where nuclear weapons are present, most disputes occurring in the presence of an ongoing mutual military build up will result in war within five years. She, as with others, also finds that it is extremely rare for disputes in the absence of a military buildup escalate to war.
The findings on alliances, crises, and military buildups have led Vasquez (1993) to argue that power politics itself constitutes a series of steps to war, each of which when taken increases the probability of war between equal states. This suggests that in order to bring about a peaceful system, states must transcend the power politics game and develop ways of making authoritative decisions in the absence of government on some basis other than coercive diplomacy. Research that tries to identify the characteristics of peaceful systems has shown that such systems exhibit efforts to develop a set of “rules of the game” among major states, and embody an acceptance of the pacta sunt servanda (agreements must be kept) norm in international law. This suggests, contrary to realism, that the world is not always in a constant war of all against all.
Other research shows that war may be confined to states that have a certain kind of relationship or contend over certain types of issues. Research by Russett (1993) and by Ray (1995) has shown that democracies rarely fight each other. This is thought to be a result of domestic constraints placed on democratic governments by their publics and/or that democratic states develop norms in dealing with each other that promote the resolution of conflict without resorting to armed force. This set of findings supports the idea of a liberal peace promulgated by Kant and recently articulated by Michael Doyle.
Such findings raise the possibility that there might be other zones of peace. Most interstate wars are fought between neighbors; in fact, the only wars not fought between neighbors are those involving major states. For some, this finding suggests that states fight primarily over territorial issues (see Hensel, 1996) and that the probability of war is highest when territorial disputes between equals are handled in a power politics fashion. Vasquez predicts that once neighbors settle their border claims, the probability of their fighting will go way down even if other contentious issues arise.
Research on the termination and impact of war has produced clearer findings than those on the causes of war. States with more revenue have won almost 80 percent of their wars, and states that have suffered a lower percentage of battle deaths in proportion to their population have won about 75 percent of their wars. Being both wealthier and having lost a lower percent of population increases the probability of victory to 84 percent. Typically, major states defeated in world wars recover, in terms of economic power, in about fifteen to twenty years. World wars are frequently associated with shifts in global leadership, with third parties sometimes benefiting the most. Domestically, world wars tend to increase the power and size of the state, giving it a permanent increase in its tax revenue and expanding its expenditures (Rasler and Thompson, 1989).
[See also Disciplinary Views of War: Causes‐of‐War Studies.]
Bibliography
- Quincy Wright, A Study of War, 1942.
- Lewis F. Richardson, Statistics of Deadly Quarrels, 1960.
- David Singer, ed., The Correlates of War, Vols.
1 and2 , 1979, 1980. - Bruce Bueno de Mesquita,
Risk, Power Distributions, and the Likelihood of War , International Studies Quarterly,25 (December 1981), pp. 541–68. - Jack S. Levy, Alliance Formation and War Behavior,
Journal of Conflict Resolution ,25 (December 1981), pp. 581–613. - Michael D. Wallace, Armaments and Escalation: Two Competing Hypotheses,
International Studies Quarterly ,26 (March 1982), pp. 37–56. - Paul F. Diehl, Armaments and Escalation: A Closer Look,
Journal of Peace Research , vol.20 , no.3 (1983), pp. 205–12. - Russell J. Leng, When Will They Ever Learn?
Journal of Conflict Resolution ,27 (September 1983), pp. 379–419. - Michael Doyle, Liberalism and World Politics,
American Political Science Review ,80 (December 1986), pp. 1151–69. - Karen Rasler and William R. Thompson, War and State Making, 1989.
- Bruce Bueno de Mesquita and David Lalman, War and Reason, 1992.
- Bruce Russett, Grasping the Democratic Peace, 1993.
- John A. Vasquez, The War Puzzle, 1993.
- James Lee Ray, Democracy and International Conflict, 1995.
- Paul R. Hensel, Charting a Course to Conflict: Territorial Issues and Intersate Conflict, 1816–1992,
Conflict Management and Peace Science ,15 (Spring 1996), pp. 43–73. - Michael Brecher and Jonathan Wilkenfeld, A Study of Crisis, 1997.
- Susan G. Semple, Arms Races and Dispute Escalation: Resolving the Debate,
Journal of Peace Research ,34 (February 1997), pp. 7–22. - Manus Midlarsky, ed., Handbook of War Studies,
2nd ed. , 2000
