Erik Gartzke




The Relevance of Bargaining in International Politics



Bargaining theory offers a compelling logic of the causes of war and peace, but the perspective has proven remarkably resistant to empirical assessment. There is also considerable ambiguity about the conditions under which novel predictions of bargaining theory matter substantively, and where the insights of other perspectives are at least as valid. I use interactions among three major bodies of ``rationalist'' theory to identify unique empirical implications and scope conditions for the bargaining perspective. Bargaining and the realist perspective emphasize, respectively, uncertainty and relative capabilities as predictors of war, while neither pays much attention to the impact of distance on their respective causal arguments. Political geography introduces the notion of the loss-of-strength gradient (among other insights), while failing to incorporate the effects of relative power and information asymmetry. A simple bargaining model illustrates how capabilities, proximity and uncertainty interact to affect conflict. I then provide evidence of an interaction between capabilities and distance predicted by the bargaining model. Weak states seldom fight far from home, while conflict increases with distance for the most capable countries. Capabilities have limited salience for conflict beyond mitigating distance.



Blame it on the Weather: Seasonality in Interstate Conflict



Historically, fighting is widely believed to follow the seasons, tending to begin or increase in spring or summer and decline or terminate in the fall and winter. While not a new subject, the seasonality of conflict has received relatively little careful systematic study. I find significant annual variation in the advent or termination of wars. However, the overall relationship between conflict and seasonal climate change is more complex. Given that climate varies both temporally and geographically, it is possible to adjust the location of at least some contests, in effect changing the weather, rather than waiting for the weather to change. I offer an explanation of the cyclicality of wars and the relocation of other disputes. States tend to shift the location of modest contests and non-territorial disputes with the seasons. In the northern hemisphere, disputes occur an average of 556 kilometers (345 miles) farther south in winter than in summer. Wars and territorial disputes that are difficult to relocate geographically tend to exhibit more seasonal variation in onset and termination. The presence of both temporal and spatial cyclicality implies that the effects of climate change may vary for conflicts of different types and intensities.



Power, Parity and Proximity: How Distance and Uncertainty Condition the Balance of Power

With Alex Braithwaite




Research debating competing perspectives on power and war has yet to address the endogenous impact of proximity. If power declines in distance, then power relations between two nations differ at different points on the globe. Claims about the impact of parity or preponderance on conflict and peace then really only apply to particular points or regions in the space separating borders or national capitals. We use a formal bargaining model to demonstrate that dyads should be most prone to fight in places where each state's capabilities, discounted by distance, are roughly at parity. We then assess this relationship empirically, introducing the directed dyad year location unit-of-analysis to capture the impact of geographic distance on power and the propensity to fight. With roughly 1 x 10^11 observations, it is not practical to construct the actual dataset. Instead, we combine all dispute locations with a random sample of non-dispute locations, correcting for bias during estimation. Results confirm that disputes are most likely at locations where the distance-weighted capabilities of nations are roughly equal.



The Myth of Cyberwar: Bringing War on the Internet Back Down to Earth




Cyberwar has been described as a revolution in military affairs, a transformation of technology and doctrine capable potentially of even overturning the prevailing world order. Yet, such conceptions of change reflect a common tendency to conflate means and ends; studying what could happen in cyberspace (or anywhere else) makes little sense without considering how internet conflict is going to accomplish the tasks commonly addressed by terrestrial warfare. To supplant existing modes of conflict, cyberwar must be capable of realizing the political objectives to which force or threats of force are commonly applied, something that in important respects cyberwar fails to do. Cyberwar is much more likely to serve as an adjunct to, rather than a substitute for, existing forms of political violence. Indeed, rather than threatening existing hierarchies, cyberwar appears much more likely to augment the military advantages of status quo powers.



Where Nations Fight: Capabilities, Interests and Contiguity in Interstate Disputes




Much has been written about why nations fight. Less attention has been devoted to explaining where countries exert and endure militarized violence. A simple game theoretic bargaining model that takes into account both the onset and location of disputes identifies differences in how capabilities and national interests affect each stage of a contest. National capabilities, which are generally thought to explain the why of conflict, may actually do more to determine where disputes occur. In contrast, the model predicts that the compatibility or incompatibility of preferences is much more salient for conflict onset or initiation. The model also helps to unravel a longstanding debate about why proximate countries fight more often. Neighbors have both greater opportunity and possibly increased willingness to fight. Using data on the location of militarized disputes, I show that capabilities matter for where countries come into conflict, while interest affinity best predicts whether contests occur. The effects of contiguity on the onset and location of disputes suggests that neighbors are disproportionately willing to fight.



To Conquer or Compel: War, Peace, and Economic Development

 With Dominic Rohner





Theories of economic development suggest variously that national income increases or decreases the propensity for states to fight, while systematic evidence of the impact of development on warfare is ambiguous or non-existent. The lack of empirical support for nominally opposing claims can be reconciled if elements of both perspectives are partially correct. We use a formal model to construct an explanation linking economic development with interstate conflict that resolves contradictory theories and a relative paucity of evidence. Development increases the ability of states to project power while decreasing the willingness of states to engage in conflict over certain issues. High income states fight less often to conquer tangible assets or territory, but fight more often to compel adherence to preferred policies and to police the global commons.




Interdependence Really is Complex




Researchers, pundits, and policy makers have long debated whether economic interdependence pacifies or provokes conflict among states. Here, I suggest how interdependence can do both. Valuable linkages offer a mechanism for signaling and coercion short of military violence that stands to increase moderate (non-militarized) conflict behavior while reducing more intense conflict or uses of force. I offer a formal model of interdependence and conflict, testing hypotheses derived from the model against COPDAB and WEIS events datasets. Interdependence reduces militarized violence, but increases non-violent conflict. The argument also helps to account for differences between symmetry and asymmetry (i.e., interdependence as opposed to dependence).




Liberal Determinants of the Systemic Interstate Peace






The success of the democratic peace research agenda has led scholars to search for additional externalities of liberal politics and economics. Among the most promising venues is the system itself. The diffusion of democratic norms or identities could discourage conflict even among non-democracies. Yet, reconciling systemic claims with dyadic findings appears to require hypocrisy; democracies must press for peace among autocracies, while themselves continuing to use or threaten force against non-democracies. No such tension exists for other elements of the Kantian liberal triad. In particular, trade appears to consistently contribute to a systemic liberal peace.




Nuclear Proliferation Dynamics and Conventional Conflict




New nuclear nations are more prone to militarized conflict, though the overall effect of nuclear weapons on conventional disputes is neutral (Horowitz 2009; Gartzke and Jo 2009). Several processes might explain the non-linear relationship between proliferation and conflict. Nominal nuclear status could constitute a capability shock, altering the balance of power and increasing the probability of disputes. Alternately, proliferation might introduce uncertainty about relative power, again increasing the risk of conflict. Familiarity with nuclear weapons should allow countries to manage conflict more effectively, even as a growing nuclear stockpile may exacerbate tensions. Informational factors (uncertainty and learning) are statistically significant determinants of conflict, while material factors (nuclear status and stockpiles) are not so salient.



Prosperous Pacifists: The Effects of Development on Initiators and Targets of Territorial Conflict

With Dominic Rohner





Students of international relations have long conjectured diverse and sometimes contradictory connections between economic development and interstate conflict or peace. Supply side ar- guments view modern economies as more difficult to subdue or exploit through force (i.e., development creates states that are “bitter pills”). Demand side perspectives argue in contrast that development either increases or lessens the appeal of conquest among potential aggressors (i.e., development can create “prosperous pacifists”). We resolve this debate by means of a formal model that isolates contrasting consequences of development for initiators and targets. We then test hypotheses drawn from the model on measures of territorial conflict, showing that the development of potential initiators, not of targets, best discourages conflict among nations.



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