Quick Facts

Random facts about the patterns in conflicts:

Duration
For conflicts that began and ended after 1945 (Fearon and Laitin 2003; Fearon 2004):

• The median duration of interstate wars was less than 3 months.
• The median duration of civil wars was about 7 years. 

End

Consistent through different coders (Pillar 1983; Stedman 1991; Licklider 1995; Walter 1997):

• Military victory is more common than negotiated settlement in civil wars.
• Negotiated settlement is more common than military victory in interstate wars. 
• Pillar: about two-thirds of interstate wars end in negotiated settlements; about two thirds of intrastate wars end in military victory.

• Between 1940 and 1990, 42 percent of civil wars (seventeen out of forty-one) experienced some form of formal peace negotiation, and 94 percent of these cases drafted at least a cease-fire accord (Walter 1997).

Literature Review: Balancing, Bandwagoning and Walt

• Walt, Stephen M. 1985. "Alliance Formation and the Balance of Power." International Security 9: 3-43.
• Walt, Stephen M. 1987. The Origins of Alliances. Ithaca: Cornell University Press.

Walt (1985, 1987) draws a contrast between balancing (allying against a threat) and bandwagoning (allying with the threat). He contends that balancing should be more common than bandwagoning and supports his contention with a survey of alliances in the Middle East. This conclusion is not surprising from the perspective of the argument here. Threats arise from differences in position on issues on which the threatening nation pursues change. Because alliances require agreement between the allies over some set of issues, nations will generally not ally with nations that threaten them for the lack of areas of agreement. Balancing alliances have the common interest in resisting the threatening nation to bring the allies together.

Bandwagoning alliances could form for two reasons: (1) because both parties face a common threat from a third nation or (2) because the threatening nation receives concessions to deactivate the threat. The former leads to a symmetric alliance; the latter, to an asymmetric alliance. An example of the former from Walt's 1987 cases would be Jordan's alignment with Egypt on the eve of the Six Day War. Balancing alliances can also be either symmetric or asymmetric. NATO is an example of an asymmetric balancing alliance.

From: Morrow, James D. 1991. "Alliances and Asymmetry: An Alternative to the Capability Aggregation Model of Alliances." American Journal of Political Science 35(4): 904-933.

Literature Review: Balance of Power and Power Transition Theories of Alliances, Morgenthau, Organski, Kugler, and Bueno de Mesquita

• Morgenthau, Hans J. 1973. Politics among Nations: The Struggle for Power and Peace. 5th ed. New York: Knopf.
  
• Organski, A. F. K. 1968. World Politics. 2d ed. New York: Knopf
• Organski, A. F. K., and Jacek Kugler. 1980. The War Ledger. Chicago: University of Chicago Press.
• Bueno de Mesquita, Bruce. 1988. "The Contribution of Expected Utility Theory to the Study of International Conflict." Journal of Interdisciplinary History 18: 629- 52.
• Singer, J. David, Stuart Bremer, and John Stuckey. 1972. "Capability Distribution, Uncertainty, and Major Power War, 1820- 1965." In Peace, War, and Numbers, ed. Bruce M. Russett. Beverly Hills: Sage.

The balance of power and power transition theories of alliances argue for different conceptions of the fundamental role of alliances than the capabilities aggregation model and the security-autonomy trade-off model of alliances. In the balance of power theory (Morgenthau 1973), nations form alliances to offset growing powers and restore the balance. Alliances in a balance of power system should be nonideological and last as long as the immediate threat. This view is the capability aggregation model. Prospective allies are just capabilities that can be added through alliance, and once the threat to the balance has been countered, the alliance is unnecessary and should be broken.

The power transition theory (Organski 1968; Organski and Kugler 1980) postulates an international system dominated by one nation. This dominant state forms a large alliance from the lesser powers that share its ideology. Nations not in this satisfied coalition may form alliances dedicated to the overthrow of the existing international system. Alliances in a power transition system should be ideological and long-lasting.

From the perspective of the argument of this paper, the theories are both correct and incorrect because, as Bueno de Mesquita (1988, 641-42) points out, they make different assumptions about the distribution of capabilities in the system. Balance of power theory assumes an international system composed of a number of major powers with relatively equal capabilities. The role of minor powers is ignored because they do not possess sufficient capabilities to shift the balance of power. In the international system postulated by balance of power theory, only symmetric alliances can be formed because all possible allies have equal capabilities. Alliances are formed only to gain security (i.e., nonideological) and do not persist because they are symmetric. Power transition theory, however, assumes a system with one dominants tate holding a preponderance of power. Any alliance that the dominant state forms is asymmetric. (Symmetric alliances are those in which both allies receive security or autonomy benefits. Asymmetric alliances are those in which one ally gains security and the other autonomy.) Alliances in a power transition system are formed to advance the autonomy interests of the dominant state or challenger (i.e., ideological) and persist because they are asymmetric.

Both theories are right in the sense that given their assumptions about the international system and their focus on relations among equals or between the dominant state and all others, their conclusions about alliances follow. However, widening our analysis of alliances shows that those conclusions are not general. The argument presented in Morrow (1991) also explains why both theories should be able to find supporting evidence in the historical record. Scholars generally see the nineteenth century as a balance of power period, while the power transition model fits the twentieth century better (e.g., Singer, Bremer, and Stuckey's 1972 results on the effects of systemic concentration of capabilities on war). The alliances examined in Morrow (1991) reflect this observation; symmetric alliances are formed more frequently in the nineteenth century (26 symmetric alliances versus 16 asymmetric alliances) than in the twentieth century (62 to 60). But in both centuries, asymmetric alliances last longer on the average than symmetric alliances.

From: Morrow, James D. 1991. "Alliances and Asymmetry: An Alternative to the Capability Aggregation Model of Alliances." American Journal of Political Science 35(4): 904-933.

Literature Review: Alliances and Thies

• Thies, Wallace J. 1987. "Alliances and Collective Goods: A Reappraisal." Journal of Conflict Resolution 31: 298-332.

Thies (1987) examined a host of pre-World War II alliances that depended on conventional armaments producing deterrence as well as impure public benefits such as damage-limiting protection in times of conflict. Based on a visual examination of some income and military spending data, Thies (1987) concluded that most of these alliances demonstrated behavior more in keeping with the joint product model for which allies are motivated by private excludable defense benefits.

From: Conybeare, John A. C., and Todd Sandler. 1990. "The Triple Entente and the Triple Alliance 1880-1914: A Collective Goods Approach." American Political Science Review 84: 1197-1206.

Literature Review: Arms Race and Michael Horn

• Horn, Michael Dean. 1987. "Arms Races and the International System." PhD dissertation. Rochester, NY: Department of Political Science, University of Rochester.
• Richardson, Lewis F. 1960. Arms and Insecurity. Pacific Grove, CA: Boxwood Press.
• Huntington, Samuel P. 1958. "Arms races: prerequisites and results." Public Policy 8: 41-86.
• Wallace, Michael D. 1979. "Arms races and escalation: some new evidence." Journal of Conflict Resolution 23: 3-16.
• Morrow, James. 1989. "A Twist of Truth: A Reexamination of the Effects of Arms Races on the Occurrence of War." Journal of Conflict Resolution 33(3): 500-529.

Horn (1987) offers an independent means of determining when two countries are engaged in an arms race. His relatively straightforward measure has two qualifications for definition as an arms race. First, that the growth rates of a country's military expenditures are on average higher in the period preceding a dispute than in the whole period under study (for him, the Correlates of War period from 1816 to 1980). Second, in order to be classified as an arms race, the growth rate must be higher in the second half of the period than in the first. In this, he attempts to include the criterion of acceleration which is so vital to the Richardsonian distinction between stable and unstable arms races (Richardson, 1960, pp. 74-75). Only when growth is speeding up or seemingly out of control is there an arms race.

He finds that of longer arms races (he looks at Huntington's twelve-year period, cf. Huntington, 1958) over one-half end in war (Horn, 1987, p. 56). Experimenting with a shorter time period, Richardson's suggested six years (Richardson, 1960) yielded no significant relationship. He concludes from this that an arms race over the longer period is indicative of a continuing conflict of interests and/or hostile relationship between countries, but the shorter measure could easily catch incidental or shortterm conflicts that never reach the level of war.

He determines that arms races are considerably rarer than others have thought, but they do have some relation to the escalation of disputes to war, though his findings are less robust than Wallace's (Horn, 1987, p. 60; Morrow, 1989, p.502).

From: Sample, Susan G. 1997. "Arms Races and Dispute Escalation: Resolving the Debate." Journal of Peace Research 34: 7-22.

Literature Review: Arms Race, Michael D. Wallace, Erich Weede, Michael F. Altfield, and Paul F. Diehl

• Wallace, Michael D. 1979. "Arms races and escalation: some new evidence." Journal of Conflict Resolution 23: 3-16.
• Weede, Erich. 1980. "Arms Races and Escalation: Some Persisting Doubts." Journal of Conflict Resolution 24(2): 285-287.
• Wallace, Michael D. 1980. "Some Persisting Findings: A Reply to Professor Weede." Journal of Conflict Resolution 24(2): 289-292.
• Altfield, Michael F. 1983. "Arms Races? — And Escalation? A Comment on Wallace." International Studies Quarterly 27(2): 25-231.
• Diehl, Paul F. 1983a. "Arms Races and Escalation: A Closer Look." Journal of Peace Research 20(3): 205-212.
• Diehl, Paul F. 1983b. "Arms Races and the Outbreak of War, 1816-1980." PhD dissertation. Ann Arbor, Ml: Department of Political Science, University of Michigan.
• Diehl, Paul F. 1985. "Arms Races to War: Testing Some Empirical Linkages." Sociological Quarterly 26(3):  331-349.

In 1979, Michael Wallace published a pathbreaking study in which he found a very strong relationship between the existence of an ongoing arms race between two countries and the escalation of a militarized dispute between them to war. Looking at 99 militarized disputes among the major states between 1816 and 1965, he found that 23 of the 26 disputes that escalated to war were characterized by an ongoing arms race (Q = 0.98 and phi = 0.80). In other words, if an arms race was going on between two countries, there was an 82% chance that a militarized dispute between them went to war. On the other hand, only about 4% of the disputes that occurred when both countries were not arming at abnormally high rates escalated to war (Wallace, 1979).

Wallace's conclusions were an empirical challenge to many long-held assumptions about politics among nations, including some of the foundations of deterrence theory. However, as Weede asserted, Wallace's results were not inconsistent with the para bellum hypothesis: 'according according to most realist or conservative thinking in the West... the most dangerous occurrence is not a runaway arms race but the status quo powers losing the arms race' (Weede, 1980, pp. 286-287). In other words, if a revisionist power strives to overturn the balance of capabilities, it is likely that both the revisionist and the status quo states will show high growth rates, but the relevant change is that of the power balance, not the rate of arming. In answer, Wallace used the ratio of expenditure growth rates between revisionist and status quo states to determine who 'won' the race.

There was some small difference in escalation between a 'victory' on the part of the status quo state or the revisionist one, but the relationship is much weaker than Wallace's original test (Wallace, 1980). A further test, using a static measure of comparative capabilities (the ratio of absolute military expenditures between the revisionist and status quo states) rather than the dynamic ratio of growth rates, achieved even weaker results for the para bellum hypothesis (Wallace, 1981). These findings lend support to Wallace's conclusion that it is the arms race itself, rather than the power balance, which is dangerous.

The two supports of Wallace's study, the disputes he used and the index he employed, both suffered massive criticism. The problem with the sample was that the strength of the findings seemed dependent on the division of the obviously multilateral World Wars into dispute dyads, hence overweighting the arms races that preceded those wars. If a small number of arms races make up the bulk of the supportive findings, it is evident that the certainty with which one is able to make general conclusions about the relationship between arms races and war is undermined.

The index that Wallace used to determine the existence of an arms race was also challenged. On theoretical grounds, it has been attacked as placing too great an emphasis on the last two years of military spending before a crisis, therefore capturing war preparations rather than an independent arming process. A further problem is that the index is multiplicative - the final index score for the dyad is arrived at through multiplying individual country scores together (Altfeld, 1983). It is conceivable that heavy unilateral buildups could be mistaken for arms races. Certainly in the former case, but possibly in the latter as well, conclusions drawn about the relationship between arms racing and dispute escalation might be overstated. A truly complete study would demand that the index be replicated, but that has yet to be done...

Diehl's work (1983a, b, 1985) on the subject of the relation of arms race and dispute escalation is an independent alternative to that of Wallace (1979, 1980, 1982, 1983, 1990). Although he criticizes Wallace at length, he does remain focused on the real issue by offering an alternative means of testing the identical proposition. Unlike Michael Wallace, he found little connection between arms races and dispute escalation. Fewer than 30% of the disputes that he finds occurring during an arms race escalate to war. The corresponding correlation coefficients are very different: Yule's Q drops from 0.98 to 0.42, and phi is an unimpressive 0.13 (Diehl, 1985, p. 338).

Diehl objects to Wallace's findings on both grounds: that his dispute sample was overweighting the World Wars, and that reliability and validity of his index were questionable. Therefore, he offers both a new index and a new set of disputes. In doing this, the criticisms of Wallace's work fail to be compelling because it is impossible to determine the extent of the effects of each weakness. We can certainly guess that both the dispute set and the index are flawed, but without being able to compare them to anything it is impossible to tell whether or not the assertion is true, or, more importantly, what particular influence these factors have had on the conclusions Wallace has drawn. Without such a comparison, it is impossible not to consider the possibility that Wallace has just found a superior means of dividing dangerous from non-dangerous arms buildups.

From: Sample, Susan G. 1997. "Arms Races and Dispute Escalation: Resolving the Debate." Journal of Peace Research 34: 7-22.

Literature Review: Tinderbox Hypothesis, Michael D. Wallace, Paul F. Diehl, and Mike Horn

• Wallace, Michael D. 1979. "Arms races and escalation: some new evidence." Journal of Conflict Resolution 23: 3-16.
• Wallace, Michael D. 1982. "Armaments and escalation." International Studies Quarterly 26: 37-56.
• Diehl, Paul F. 1983. "Arms races and escalation: a closer look." Journal of Peace Research 20: 205-212.
• Horn, Mike. 1984. "Arms races and the likelihood of war." Presented at the annual meeting of the International Studies Association, Atlanta, GA, March 27-31.

Wallace (1979, 1982) presented the first attempt to develop a comprehensive list of arms races and test the arms race hypothesis. He constructed his list of arms races by examining the military expenditures of participants in serious disputes, specifically those involving at least a threat to employ force prior to those disputes. Wallace's arms race index attempted to capture not only the growth in military expenditures of an arms race but also the underlying conflict between the racing parties by searching for arms races prior to serious disputes. However, this procedure would miss any arms race that did not end in a serious dispute, and consequently cannot provide a complete test of the arms race hypothesis. Instead, Wallace tested whether arms races made escalation to war more likely, or what could be termed the "tinderbox hypothesis." The tinderbox hypothesis states that arms races do not necessarily cause wars, but they do create an inflammable situation between the racing nations where even the slightest spark can

push a blaze to war.

Wallace found impressive results supporting the tinderbox hypothesis: 23 of the 28 disputes preceded by an arms race escalated to war. However, Wallace's determination of arms races and his accumulation of the results suffer from two methodological flaws: His arms race index may have been misleading, and he decomposed multilateral disputes into separate dyads (see Weede, 1980; Altfeld, 1983; and responses by

Wallace, 1980, 1983).

Diehl (1983) and Horn (1984) reanalyzed the tinderbox hypothesis using the same data as Wallace but different arms race indices, and without decomposing each dispute into separate dyads. Both required both sides' average growth in military expenditures to exceed certain thresholds over a set period of time prior to the dispute. Dichl (1983) found that only 3 of 12 disputes preceded by an arms race escalated to war. Horn (1984) found that at most 60% (9 out of 15) of 6-year arms races and 46% (6 out of 13) of 12-year arms races ended in war. These reanalyses suggest that the tinderbox hypothesis is only partially true; disputes preceded by arms races do escalate to war more often than other disputes, but they do not overwhelmingly escalate to war.

From: Morrow, James D. 1989. "A Twist of Truth:  A Reexamination of the Effects of Arms Races on the Occurrence of War."  Journal of Conflict Resolution 33(3): 500-529.