Miller, Benjamin. States, Nations, and the Great Powers: The Sources of Regional War and Peace. Cambridge: Cambridge University Press, 2007.

This book seeks to address two related empirical questions about interstate conflict: to account for transitions between war and peace in different regions across time, and to explain variations in the level of regional peace that exists in different regions in a particular time period. (p. 369) Benjamin Miller’s explanation crosses the typical levels-of-analysis divide in international relations in its suggestion that both regional and international factors play a crucial role. On its face, Miller’s argument appears straightforward and parsimonious as he points to only two explanatory variables: great power involvement and state-to-nation congruence. However, as explained below, the causal mechanisms of his argument are more complicated than first admitted.

Miller proposes that the state-to-nation congruence in a given region shapes its risk of conflict. Moreover, whether regional outcomes are “hot” or “cold” depends on domestic and regional factors (i.e., the strength of the state and the extent of the imbalance between states and nations), international factors, and the type of great power involvement, respectively. Miller claims his approach unifies realist and liberal approaches: great power involvement is considered a structural (i.e., realist) force, while the state-to-nation balance is regarded as a domestic (i.e., liberal) factor. (p. 21-23) The state-to-nation balance, which can be either internal or external, is an important factor in determining whether first, strong states are status quo enforcing when congruent or revision seeking when incongruent, and second, weak states are frontier states (i.e., prone to boundary conflicts) when congruent or failed states when incongruent. Internally incongruent states have more than one national group inside the territory (i.e., Switzerland) whereas externally incongruent states arise when a national group resides within several state territories (i.e., the Kurdish nation). Miller suggests that internal and external congruence are equally important. (p. 56) Great power behavior in regional environments can be characterized by cooperation or competition when more than one actor is involved; however, in the case of a single great power acting in a region, there can be either hegemony or disengagement.

After establishing this general framework Miller’s argument goes on to suggest that regime type or “liberal compatibility” (p. 61) acts as an extremely important intervening variable, leading to either a “normal peace” between non-democracies or a “high-level warm peace” between democracies. The difference between normal and high-level peace is related to the risk of returning to conflict: for high-level peace, consistent with the democratic peace proposition, there is no risk of war; for normal peace, there is minimal risk of conflict if revisionist states arise. (p. 47) Different combinations of the explanatory factors will lead to either hot/cold war (incongruence + competition/disengagement), cold peace (incongruence + cooperation/hegemony), normal peace, or high-level warm peace. (p. 66)

All told, Miller’s claim of theoretical parsimony seems suspect. First, though he attempts to present a simple 2x2 table (p. 64) to place states into four categories, his failure to differentiate between the internal and external elements of incongruence (which might mask considerable differences in conflict dynamics), the fact that the categories themselves are not mutually exclusive, and the fact that great power involvement takes four values instead of the two depicted in the table, all suggest that the reality of war and peace is more complex than specified in the base theory. Moreover the insertion of regime type could be seen as either an attempt to adopt post hoc auxiliary propositions or as an implicit admission that the state-to-nation balance does not sufficiently capture liberal arguments. Regardless of the increasing complexity of the theory, however, Miller does identify expected outcomes and examines his expectations based on qualitative comparative case studies over several chapters.

The case studies of the Middle East, Western Europe, Latin American, and the Balkans provide evidence to support many of the author’s claims. However, some concerns remained for this reader with respect to the case studies. First Miller suggests great powers employ a single strategy in their regional involvement in a given time period; yet an examination of the case for European integration in the Cold War suggests the US simultaneously pursued cooperative policies over political and economic integration while discouraging cooperation in the security domain. The US has historically viewed independent European security cooperation as a substitute for NATO; thus, the development of a European common foreign and defense policy is viewed as competing with that of NATO’s to the extent that European states allocate resources away from NATO.

Second Miller suggests that democracy resolves the state-to-nation imbalance. However, democracy must be properly structured in order to rectify the imbalance via representation or it risks unifying those marginalized against the government. Furthermore, he points to South America as an example of a case where state-to-nation imbalance has been resolved via democracy, thus reducing the risk of conflict. However, it might otherwise be claimed that democracy has not reduced the risk of conflict; instead the unwillingness of the US to change the balance of capabilities, the incapacity of those states to internally increase capabilities, and the collective action problem have limited the capacity of political actors to challenge the state-to-nation imbalance. The recent electoral success of “leftist” collective action movements in places Bolivia, Argentina, Columbia, and Venezuela on the basis of indigenous rights and egalitarianism suggests an imbalance remains despite “consolidated” democracy.

Despite these weaknesses, Miller presents an interesting theory capable of explaining both civil and interstate conflicts within a regional context by transcending the typical levels of analysis divide. As such, this book presents a step forward for conflict studies.

Anessa L. Kimball is an Assistant Professor in the Department of Political Science at the Université Laval.