DYADIC LEVEL OF SOCIAL AGGREGATION

Within the peace science community there has been considerable debate as to the usefulness of trying to describe and explain armed conflict at the state level; dissatisfaction with that emphasis has led to a veritable cottage industry of research that reflects the proposition: “It's the dyad, silly, not the monadic.” We thus turn now to some of the more promising findings at the dyadic level.

Capability and parity

The first variable deals with the impact of the direction and rate of change in relative capabilities on the likelihood of war at the dyadic level. There are two dominant schools of thought: parity and preponderance. The parity school holds that the more equal two states are in military and industrial capabilities, and thus uncertain as to which can dominate in a confrontation, the less likely they are to risk war against one another as each can successfully deter the other (Waltz, 1979). Thepreponderance school, on the other hand, holds that the very uncertainty of victory can lead to instability in the dyad, and create temptation on the part of one or another of the parties to strike first, especially as capabilities shift.

Closely related is the so-called “Power Transition” paradigm, in which it is argued that when two major powers are mov­ing toward parity in their capabilities, the likelihood of war will rise (Organski and Kugler, 1980). Another perspective concerns the number of major powers in the system; Deutsch and Singer (1964) state that a bipolar configuration is dangerous and that the number of fairly distinct coalitions or poles decreases the likelihood of war between any two members in the major power subsystem.

Using data for the years 1815 through 1965 to examine both the initiation and escalation of international conflicts, Siverson and Tennefoss (1984) also provide evidence in general support of the basic hypothesis.

Kim (1991) also examines great power wars (COW database 1816-1975) and reports that the probability of war for major power dyads whose capabilities (including alliances) were equal is more than double the prob­ability for dyads whose capabilities were unequal. In an expanded analysis, Kim (1996) examines the interaction of dyadic capability balances, status quo orientation, and alliance relationships among great powers for the period from the Peace of Westphalia in 1648 to 1975. His findings indicate that basic equality in capabilities between great powers and dissatisfied challengers increases the probability of the onset of war.

Shifts and transitions in regimes have also been tested for correlations with war on the dyadic level. Houweling and Siccama (1988) provide a re-analysis of the Organski and Kugler power transition test using a more extensive set of nations (all major powers) and a composite indicator of national capabilities (CINC). They conclude that differential growth rates that result in capability transi­tions toward parity are strongly associated with the occurrence of major power war.

Continuing the analysis of capability change and the onset of interstate war, a study by Kim and Morrow (1992) reports the absence of any statistically discernible association between war occurrence and the rate of capability change among major power rivals. On the other hand, Huth, Bennett, and Gelpi (1992) report significant effects for capability transitions on dispute initiation patterns (MID Database) among a set of 18 great power rivalries for the period from 1816 to 1975. The findings indicate that a capability “transition” (defined as a military expenditure growth rate differential of 10 percent or more) has a significant and positive impact on the initiation of militarized conflict among great power rivals.

Taking this analysis a step further, Wayman (1996) compares capability shifts in non-rival and rival dyads, and analyzes a set of major power rivalries (COW database) and com­pares their capability and war patterns with non-rival dyads. He reports that the statistical association between capability shifts and war is stronger among rival states than for non­rivals, and that a capability shift within a rival dyad approximately doubles its probability of war.

Recurring conflicts

Also at the dyadic level, an interesting area of research has been that of recurring conflicts. Gochman and Maoz (1984) report that 76 percent of militarized disputes are followed by another dispute between the same states within a brief period of time.

Nuclear weapons

Since the bombing of Hiroshima and Nagasaki, most observers have expressed serious concern and alarm at the possibility that nuclear weapons will proliferate. On the other hand, a few observers have argued that the gradual spread of nuclear weapons will promote peace and reinforce international sta­bility, as they assume that nuclear weapons are the agents of equalization and thus the means by which to create a balance of power in the international system.

Geller (2003) uses Doran’s power cycle conjecture to gain better insights into the global ramifications of a nuclear arms race. He guesses that an arms race between Pakistan and India would trigger China to increase its own nuclear stockpile, which would then force Russia to do the same, and consequently the United States as well.

Proximity of states

Shifting now to studying the proximity of states and how that might affect war initiation on the dyadic level, Diehl (1985) finds that the probability of dispute escalation to full-scale war is much greater for dyads in which at least one of the states is contiguous to the site of the dispute. Bremer (1992) studies 202,778 non-directional dyad-years for the period between 1816 and 1965, and classifies dyads as either land contiguous, sea contiguous (separated by 150 miles or less of water), or non-contiguous. He concludes that the probability of war increases significantly with the presence of either land or sea contiguity. If the categories of land and sea contiguity are combined, then the probability of war between contiguous states is approximately 35 times greater than the likelihood of war between non-contiguous nations. Lending support to Bremer's findings is Kocs (1995) who also finds that contiguous dyads with an unresolved territorial claim were more than forty times more likely than other dyads to go to war during the 1945-87 period, thus asserting the basic claim that territorial disputes are a very important determinant of war initiation.

Alliances

The standard classification of formal alliances is that of Singer and Small (1966), consisting of defense pacts, non-aggression treaties, and ententes. Defense pacts are formal treaties in which each signatory commits to defend its allies in the event of an attack on one of them, non-aggressive neutrality pacts are self-evident, and the entente is merely an understanding to consult. Weede's (1975) analysis of military conflicts among 3321 dyads for 1950 through 1969 shows that common bloc membership (alliance) served to reduce interstate conflict between members of a dyad. Bremer (1992) similarly concludes that the absence of an alliance (in conjunction with other factors) increases the war-proneness of a dyad. On the other hand, Vasquez (1993) argues that while major powers are more prone to get involved in wars and alliances than minor states, once they have formed an alliance, their probability of going to war increases further. In the case of minor states, he argues that since their capabilities are substantially less than that of majors, alliance initiation on their part is probably an attempt to avoid a future war. Also, Maoz (1997) finds that alliance commitment has a significantly and consistently pacifying effect on conflict outbreak, conflict occurrence, and conflict escalation. However, it is useful to bear in mind (Sabrosky, 1998) that during the period from 1816 to 1992, defense pact commitments were only honored in 30 odd percent of the cases.

Democracy and war

We have already mentioned the analysis of democracy on the monadic level, but a good many scholars agree with Small and Singer (1976) who are quite skeptical. Many also doubt that the empirical findings can be explained by the democratic peace argument, since it neglects a number of other factors. Henderson (1999) argues that “factors includ­ing bipolarity, nuclear deterrence, alliance membership, and trade links contributed to the formation of an international security regime among the major power democracies and their minor power democratic allies” thereby explaining the peace as not simply a byproduct of the existence of a certain regime type. There is still considerable scholarly support for the democratic peace argument at the dyadic level, yet the results that have accumulated are complicated and by no means conclusive. Maoz andAbdolali (1989) examine all nation­dyads in the international system for the years between 1816 and 1976, including militarized disputes as well as wars, and report that democratic states are significantly less likely to engage in militarized conflict or war with each other than are dyads with other regime types.

Gleditsch and Hegre (1997) found that if the conventional wisdom holds at the dyadic and national levels, the probability of war in a politically mixed dyad must be higher than the probability of war between non­democracies, and the relationship between democracy and war at the system level must be an inverted u-shape, which means that increasing democratization initially produces more war, and the reduction of war starts only at a higher level of democratization. Another study by Remmer (1998) draws upon a data set covering dyadic interactions among Mercosur (Latin American) nations during the 1947-1985 period, and finds a positive relationship between democracy and cooperation.

Like many findings in this area at the dyadic level, the conclusion is that there is only limited support for the hypothesis that democracy promotes cooperation. Despite ambiguous results, many researchers, such as Maoz (1997), Oneal and Russett (1999, 2001) and Ray (2005), continue to assert their belief in a “democratic peace.” Essentially, these authors argue that disputes arising between two democratic regimes will likely be resolved as democratic leaders inherently prefer the non-military resolution; however, the argument does come with the caveat that when democratic regimes interact with non-democratic regimes, democratic leaders are more likely to see military force as a method of conflict resolution. Some, such as Gartzke (2007) and Weede (2004), have accepted that democracies are less conflict- prone against other democracies, but they dispute whether or not the finding is a result of democratization or something they term the “capitalist peace.” They assert that economic development, free markets, and trade interactions lessen militarized disputes and wars.

Status quo orientation

A recurrent and subordinate theme in the lit­erature has to do with the way in which status quo and revisionist major powers interact with one another. While not a great deal of databased work has centered around this issue, there is the study by Anderson and McKeown (1987) in which they analyze 77 wars (COW database 1816-1980) in terms of capability balances and the degree to which belligerents’ “aspirations diverge from actual or expected achievements.” Their model also finds that capability balance is associated with war initiation by both challengers and defenders of the status quo for preemptive war initiated by a status quo defender. Huth, Gelpi, and Bennett (1993) report findings for a set of nine major powers (MID database 1816-1984) in “extended and direct immediate deterrence encounters,” which suggest the salience of the conventional military balance between challengers and defenders for probabilities of conflict escalation. They conclude that a shift in the military balance “from a three- to-one defender advantage to a three-to-one challenger advantage increases the probability of escalation by approximately 33%.”

Trade and economic openness

Trade between nations has often been seen as a method of conflict prevention, and scholars such as Sullivan (1974) examine this statement by looking at the dyadic trade flow of states for evidence of conflict patterns over the brief period 1955-1957. Employing trade data generated by the UN, he reports that trade flows are negatively correlated with dyadic-level verbal conflict and are positively correlated with the percentage of cooperative interactions. An inverse relationship between trade and dyadic level conflict behavior was posited by Gasiorowski and Polachek (1982), who go even further and note that the results of a Granger casualty test indicate that trade reduces conflict.

Another economic indicator that has been studied is the level of economic development and how that relates to war. Bremer (1992) is one scholar who provides evidence regarding dyadic economic development levels and war. Using four variables from the COW material capabilities data set, he constructs two indices reflecting the demographic and eco­nomic dimensions of development and then classifies dyads as symmetrically developed, asymmetrically developed, or symmetrically underdeveloped. The multivariate results (for the years between 1816 and 1965) with six additional predictor variables indicate a negative relationship between economic development and war.

Polachek, Robst, and Chang (1999) exam­ined how the gains from trade are affected by foreign aid, tariffs, contiguity, and coun­try size (with foreign aid, and contiguity increasing the gains from trade and tariffs reducing the gains from trade). They rely on the assumption that countries seek to protect their trade gains, and that foreign aid and contiguity will decrease conflict, while tariffs will increase conflict. The contiguity results suggest that conflict between neighboring countries would be greater than observed if not for the mitigating effects of trade. They tested their results against empirical evidence from the Conflict and Peace Data Bank and they found that the results supported their hypotheses.

In contrast, Barbieri (1996) finds that extensive economic interdependence tends to increase the likelihood that dyads will engage in militarized interstate disputes. She finds that peace through trade is most likely to arise among dyads composed of mutually dependent trading partners, but that even then, the relationship between interdependence and conflict appears to be curvilinear, where low to moderate degrees of interdependence reduce the likelihood of dyadic disputes, and extensive economic linkages increase the probability of militarized disputes. Further, she finds that extreme interdependence is most likely to increase the likelihood of conflict.

Adding to Barbieri’s criticism of the “capitalist peace” argument are Bennett and Stam (2003) who suggest that there is a short-term tradeoff between economic gains and the likelihood of war. They observe that during periods of sustained economic growth throughout the system, the incidence of war increases remarkably. Across all conflict categories, the increases in risk are generally of similar magnitude, with a 40 to 100 percent increase in the odds of conflict involving force during periods of economic upswing compared to periods of downswing. The “capitalist peace” argument also does not take into account the development of a free-trade system where there is both a multiplicity of buyers and sellers; Brooks (2001) suggests that the ability of a state to substitute for lost trade through another partner might lower the economic costs of conflict associated with trade disruption.