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Power Cycles or Power Shifts?

Charles F. Doran Andrew W. Mellon Professor of International Relations

Johns Hopkins SAIS, Washington DC Prepared for International Political Science Association Meetings

Santiago, Chile July 2009

Structural change takes place across long periods of history. Rise on the state power cycle for the United States took more than a century and one-half to unfold, and decline in U.S. relative power could involve similarly long intervals. These long-term relative power changes are fueled by changes in absolute power across states in the system, but the associated changes in absolute power can mislead – as the principles of the power cycle explain, and as has been demonstrated empirically for both individual indicators and in the aggregate. The undiminished dynamism of German absolute power ascendancy made some historians believe the rise of German power prior to WWI would continue at such elevated rates that Germany was destined to become the “master of Europe,” an outcome that the German leadership on the eve of WWI itself realized was unlikely, and that subsequent empirical analysis on indicators such as German coal, steel, and oil production has shown to be impossible.

Distinct from this “power cycle” perspective, a particular notion of “power shifts” has a long and

familiar tradition in the literature on diplomatic history and the balance of power. There the term power shift often connotes, because of a change in the parity of states, a shift in the balance itself. But this notion of power shift as “shift in the balance” is not the same as that of the movement of a single state or, of a contrasted pair of states, up or down in power terms in any long-term sense. Moreover, the notion of “power shift” as “balance” is far more aggregate and pluralistic, reflecting the net position of the power balance across all of the members of the central system.

Going well beyond the classical notion of “shift in the balance,” the modern literature on power

shifts is as rich and diverse as the usage of the concept itself.1 The notion of power shift is employed in different ways by different authors, and, in turn, the focus of explanation regarding war causation also varies. Whether the objective is to explain how war occurs, or against whom, or with what consequence, or, finally, when war occurs, the objective has been assessed across a wide spectrum of applications and interpretations of the concept of power shift.

After a brief review of some meanings recently attributed to the notion of “power shifts,” a

fundamental question contends for the attention of the analyst. If “power shifts” on the cycles of relative and absolute power are perpetually ongoing, then where and when is war causation to be situated? If the answer is that the mere fact of the “rise and decline” of states is the cause of war, this explanation is too diffuse and generalized. Such an explanation is akin to the assertion that war occurs because states are

1 A sampling of the recent usage of the “power shift” terminology in writing on international relations reveals very broad differences of conceptualization. See for example the following: Jessica Mathews, “Power Shift,” Foreign Affairs, January/February 1997; James Hoge, Jr., “A Global Power Shift in the Making,” Foreign Affairs, July/August, 2004; David Held, Power Shift: From National Government to Global Governance? (New York: Routledge, 2009); David Shambaugh, Power Shift: China and Asia’s New Dynamics (University of California Press, 2009); Frank Fukuyama, Power Shift: The Debate over American Decline, Roundtable Discussion, American Abroad Media, January 2009.

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too “power-oriented,” an assertion that however true is not an adequate explanation for war since power can be used for purposes of legitimate security and defense as much as for belligerency.

What is a ‘Power Shift’?

I will briefly summarize and discuss three prominent uses of the term “power shift” in the recent literature and relate the usage of each to theoretical and operational issues in the literature on the relationship between structural change and major war.

Usage begging for specificity regarding war-causation

Widespread in the policy literature is a usage that links “power shifts” – that is, some general sense of changing relative power – with major war. For example, in a 2004 article in Foreign Affairs entitled “A Global Power Shift in the Making,” editor James Hoge, Jr., argues that

major shifts of power between states, not to mention regions, occur infrequently and are rarely peaceful. In the early twentieth century, the imperial order and the aspiring states of Germany and Japan failed to adjust to each other.2

A careful reading of the article reveals that, vis-à-vis the “global power shift in the making,” Hoge means that the future power of the United States, Europe, and Japan will be shifted downward and that of China, India, and other Third World countries will be shifted upward. In the article, Hoge does not mention either transitions or critical points or any other aspect of the rise and decline dynamic. Hence, in saying that such major shifts “occur infrequently” and are “rarely peaceful,” without providing greater specificity regarding the type or magnitude of changing relative power, the statement suggests that rise and decline in its most macro form is responsible for war. Moreover, one may infer from the historical reference to Germany and Japan in the early twentieth century that the warfare occurs because the declining and rising powers “failed to adjust to each other.” But, without greater specificity regarding the structural dynamic and how it might account for the failure to adjust, the statement regarding “power shifts” here might be taken to mean that the mere fact of such movement upward and downward on the power cycles is cause for the major warfare that ensued. If, on the other hand, the author is contemplating acceleration of change in relative power, then what is needed is an understanding of the dynamics of the power cycle and how it impacts foreign policy perception and decision-making.

Arguing the need for specificity regarding the structural dynamic and its causal mechanism has been a long-standing priority of power cycle theory. Broad power shifts are ongoing all the time – including accelerative movement such as that experienced by Germany and Japan in a prior era and by China and India today – and, the theory argues, the mere presence of large-scale movement on the power cycles is not responsible for major war. Rather, it is the abrupt alterations in these movements on the power cycles (critical points, where for example the trend of acceleration shifts to deceleration), and the expectations associated with those movements, that have made such “power shifts” difficult to navigate and hence “rarely peaceful.” Hoge’s article offers an insightful foreign policy statement with which many of us would find full agreement. It does not discuss the issue of war causation alluded to in the quoted passage; and it is only the war causation implications that follow from use of the term “power shifts” that begs for specificity regarding the dynamic of relative power change as explained by power cycle theory.

2 James F. Hoge, Jr., “A Global Power Shift in the Making: Is the United States Ready?” Foreign Affairs, Vol. 83, No. 4, July-August, 2004, pp. 2-7 (Adapted from a lecture given at Johns Hopkins University’s Paul H. Nitze School of Advanced International Studies in Washington, D.C., April, 2004).

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Usage that amounts to either “transition” or “upper turning point”

In his book Causes of War, Steven Van Evera articulates a very specialized notion of “power shifts” in a chapter entitled “Power Shifts: Windows of Opportunity and Vulnerability.”3 Beginning with the hypothesis that “war is more likely when the relative power of states fluctuates sharply,” he develops the notion of a window of opportunity for war to obtain seven sub-hypotheses regarding bellicosity and war. A window “refers to a period when a state’s relative strength is about to decline, or is in decline.” In a diagram he describes the “window” as “impending shifts in relative power” but does not explain what is meant by “shifts.” By distinguishing between “long-term” and “short-term” windows, Van Evera develops a meaning that can imply either traditional balance of power reasoning, transition theory logic, or the logic of “expectations foregone” which power cycle theory argues occurs at the upper turning point on a state power cycle. The “long-term windows arise from slow trends in the balance of power, stemming from different rates of economic growth or military buildup,” whereas the “short-term windows arise from actions that quickly change balance of power” such as military mobilizations and deployments.

In Van Evera, these “power shifts” are the agents of change, the independent variables, and their

causal relevance is made specific to “a period when a state’s relative strength is about to decline, or is in decline.” In the former situation, that is, when the state’s relative strength is “about to decline” (i.e., the window is an “impending shift”), the “period” of increased likelihood of major war could be either just prior to and after a transition or just prior to or after the peak on the power cycle of the state. So here we have a situation in which “power shift” is specified, but in completely different senses. When the Van Evera power shift takes place at the peak of the power cycle – so that the impending decline is an irreversible long-term relative decline – the ‘window of opportunity’ for war is equivalent to the “critical interval.” Whether it applies to a transition or to a critical interval, Van Evera’s is a well-defined, very specific meaning of power shift.

Of course, if ‘power shift’ is to possess the meaning equated with what takes place at the top of

the power curve, this notion of war causation is exactly equivalent to interaction between independent and dependent variable inside the interval that surrounds the upper turning point on the power cycle. This is a fully legitimate usage of the term ‘power shift,’ but it is the very restricted notion that is encompassed in the theory and empirical tests involving power cycle analysis.

At this point it is appropriate to note that the aforementioned limitations regarding the notion of

“power shift” also occur in terms of the notion of “declining power” [or of “rising power”] – namely, the lack of specificity in the independent variable “decline” on the one hand, and the incorporation of logic associated with other highly specified notions of war causation on the other hand. Consider, for instance, arguments that explain structural incentives for war solely in terms of the fact that a state is a declining state (in irreversible decline), leading to a rational decision to undertake a preventive war. I will address the critique to the particular theory espoused by one of my former students, Dale Copeland, but the critique applies to all such arguments.4 Copeland asserts, for instance, that for each of his cases, he “include[s] all the primary causal arguments that have been established to explain actor behavior” and then “use[s] the documentary evidence to test the explanatory power of these arguments” against his theory so that “we can be sure that there is no hidden variable causing the result.”

However, Copeland notably failed to include the “primary causal arguments” of power cycle

theory at any point in his analysis (so that “critical change on the power cycle” may be such a “hidden variable causing the result”). Moreover, the very logic which Copeland applies regarding Germany’s fear 3 Stephan Van Evera, Causes of War: Roots of Conflict (Ithaca: Cornell University Press, 1999). 4 Dale C. Copeland, The Origins of Major War (Ithaca: Cornell University Press, 2000).

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of irreversible deep decline is the logic of “expectations foregone” at the upper turning point as established in power cycle theory. But at the critical point, the “trauma of expectations foregone” does not have a necessary link with such a rational preventive war motivation. Essential to any analysis of World War I is assessment of the critical interval on the German power cycle amidst the broader structural changes and the severe disequilibrium between power and role throughout the system, other primary causal arguments” or “hidden variables” which Copeland likewise failed to assess. Vis-à-vis war causation, the notion of “declining power,” like that of generic “power shifts,” begs specificity.

Power Shifts from the Transition Perspective in Comparative Perspective

Jonathan DiCicco and Jack Levy’s “Power Shifts and Problem Shifts: The Evolution of the

Power Transition Research Program” 5 goes far in exposing the difficulties associated with the term “power shifts” and, in particular, in emphasizing the great difference in meaning and in causal relevance between the “transition points” and “critical points” that occur at specific times during these “power shifts.”

Doran6 maintains that power transition theory is misspecified and fails to provide as complete an explanation of major power war as power cycle theory. He tested the two theories against the same data set7 and found that power transitions are associated with major war only when coinciding with “critical points” in states’ relative power trajectories, whereas critical points do predict wars even in the absence of transitions.8

The authors in this meticulous study urge “additional competitive tests of the two theories,”9 a number of which have subsequently taken place. In the context of the question raised in this paper regarding ongoing research in the field, this means as well competitive tests of power cycles and power shifts in the broader sense. And such a competitive test must confront the full implications of the principles of the power cycle which explain at once “what sets the cycles in motion” and the nature of change on the power cycles – most notably, the necessary occurrence of the points of nonlinearity which mark a sudden reversal of the prior trend of the dynamic even when absolute trends do not change.

Although the authors discuss some of the continuing research in the transition format (the focus

of their analysis), they do not try to offer a precise definition of “power shift,” nor do they identify any other authors who offer such a precise definition. But they do emphasize that “power shifts” involve more than a consideration of the transition. They imply that the entire rise and decline of the state is encompassed in the notion of a power shift, not just the transition, and that the explanation for war is possibly located in these larger dynamics. Of course, the entire rise and decline of the state is precisely the state power cycle, and the larger dynamics is precisely what is explained by the fundamental principles of the power cycle established within power cycle theory. However, the authors do not refer

5 Jonathan M. DiCicco and Jack S. Levy, “Power Shifts and Problem Shifts: The Evolution of the Power Transition Research Program,” The Journal of Conflict Resolution 43, 6 (1999): 673-704. 6 References cited by DiCicco and Levy: Charles F. Doran, Systems in Crisis, Cambridge: New Imperatives of High Politics at Century’s End (Cambridge University Press, 1991); Charles F. Doran, “Confronting the Principles of the Power Cycle: Changing Systems Structure, Expectations, and War,” in Handbook of War Studies II, edited by Manus I. Midlarsky (Ann Arbor: University of Michigan Press, 2000). 7 Reference cited by DiCicco and Levy: Charles F. Doran, “Power Cycle Theory of Systems Structure and Stability: Commonalities and Complementarities,” in Manus I. Midlarsky, ed., Handbook of War Studies (Boston: Unwin Hyman, 1989), pp.83-110. 8 DiCicco and Levy, “Power Shifts and Problem Shifts,” 681. 9 Ibid., p. 681.

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the reader to the power cycle theory of state rise and decline – the “structural” dynamic of power cycle theory which is independent of the war causation component of the theory.10 Regarding the causal relevance of power shifts, they say, quoting Organski, that if a state is too small or too large, the state is not likely to be a source of instability. They also speculate that the speed of the challenger’s rise may have something to do with the origin of war. But for the speed of the rise to be important, the entire interval of rise and decline must be encompassed in the analysis. If by “power shift” the authors mean deceleration or acceleration of change in relative power, they are in effect referring to aspects of the dynamic of the power cycle as explicated in power cycle theory. So a major element of the “power shift” notion argued in their paper is that, without taking into account the broad sweep of structural change such as the term “rise and decline of states” implies, analysis will fail to capture the larger explanation for war.

Yet, since it does not confront the power cycle dynamic or offer an alternative dynamic, the

DiCicco and Levy usage of the term “power shift” suffers from the very lack of specificity discussed above regarding common usage in the policy literature. Both interpretations equate the notion of “power shift” with very large alterations in the structure of the system in terms of the overall rise and decline of states. This overall rise and decline corresponds to the lengthy segments of the power cycle located between the critical points. To ignore the critical points is to not acknowledge the full dynamic of change that must occur on the power cycles (the principles of relative power change that determine the nature of the trajectory, including the necessary occurrence of critical points). The notion of “power shifts” hence would merely refer to broad portions of the power cycle curve where the rise and decline of states is most visible and hypothetically (therefore) the most disruptive to world order – which is the exact opposite of the power cycle thesis regarding critical intervals on the power cycle.

Why “Power Shifts” Needs “Power Cycles”

Such power shifts (in the sense of changing relative power) are occurring all of the time.11 That is part of the problem for the power shift paradigm. As Bruce Russett has observed, the identification of when war occurs, not just of why, is a most difficult puzzle. The reality is that war is an event. It is time-specific. Therefore, the explanation for the onset of war must also possess the attribute of temporal specificity. At the very least, the explanation for war must be able to address the question not only of why war occurs but the question of when it is most likely.

Major war is a singular event. It happens at a particular point in time and geopolitical locus. Many factors contribute to its onset. But it takes place at a single point in time. Long periods of history 10 As explained in Doran, Systems in Crisis, pages 10-13, at 11, “I always emphasized that power cycle theory had these two parts so that scholars could accept the first half of the theory (the theory of the cycle of power and role) without necessarily accepting the second half (the theory of how that cycles relates to major war). In my view, the notions of power transition, and a declining hegemon can (must) be interpreted within the context of such a power cycle dynamic (whether or not proponents of those theories agree with the indicators utilized in the ultimate empirical test of the power cycle). The power cycle is an analytic paradigm within which many explanations for war may find understanding.” 11 A “power shift” viewed as mere changing relative power would refer to any movement on the power cycles. For the argument that such movement is pervasive, see Charles Doran, Systems in Crisis; “Confronting the Principles...”; and “Economics, Philosophy of History and the Single Dynamic of Power Cycle Theory,” Power Cycle Theory and Global Politics, International Political Science Review 24, 1 (2003): 13-50, in particular Figure 2 (p. 24) depicting the “dynamics of changing systems structure” in the European system, 1500-1993. See also the shifts identified in long sweeps of history in Jack S. Levy and William R. Thompson, “Hegemonic Threats and Great-Power Balancing in Europe, 1495-1999,” Security Studies 14, 1 (2005): 1-33; and William C. Wohlforth et al., “Testing Balance-of-Power Theory in World History,” European Journal of International Relations 13, 2 (2007): 155-185.

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separate major war where comparative peace prevails. Hence in attempting to comprehend the origin of major war, the point in time when major war does occur (and its unique identity) must be kept foremost in the mind of the analyst.

Second, major war is, thankfully, a rare event. War itself may not be so rare. But major war,

because of its consequence and cost, stands out in history. It can be defined rather easily. Major war is of high intensity (high casualties). It is not easily quenched (long duration). Major war is major because it involves a huge military clash among a large number of big states (high magnitude).12 Operationally magnitude constitutes: (the number of big states that are involved in war) x (their size measured in terms of relative power).

Third, major war may appear random: when governments least anticipate its occurrence, it seems

to break out.13 Yet when major war is examined against the nature of structural change within the international system, an astonishing regularity emerges.14 This observation persists for a variety of types of structural change and on various measures of major war.15 In particular, the relationship has been shown to be particularly strong regarding the critical structural change postulated in power cycle theory. In an atmosphere of high political uncertainty and invitation to belligerence, the probability of war increases sharply following each interval of abrupt, unanticipated, massive structural change known as systems transformation.

Fourth, when it is realized that, as components of a single dynamic, each state follows a cycle of

relative power (and an associated cycle of foreign policy role), rising, reaching a peak, and entering decline in relative power terms as other states also traverse their own power cycles, structural change within the international system itself is rendered amenable to very precise assessment.16 These state power cycles underlie the structure of the international system and give the system its dynamism. They precipitate systems transformation.

The singularity of major war becomes clear. At highly visible points on these power cycles

called critical points, structural change becomes sharply identifiable, and the probability of major war surges.17 Critical points are points where non-linearity occurs – that is, an inversion in the prior trend of change in relative power. Change accelerates, or decelerates, as the velocity of structural change itself abruptly alters. At these points, gaps between power and role come to the surface and demand

12 W. B. Moul, “Polarization, Polynomials, War,” Journal of Conflict Resolution 37, 4 (1993): 735-748. 13 This point is made explicitly in Michael P. Coloresi, Karen Rasler, and William R. Thompson, Strategic Rivalries in World Politics: Position, Space, and Conflict Resolution (Cambridge: Cambridge University Press, 2008). Ekkart Zimmermann, Political Violence, Crises and Revolutions: Theories and Research (New York: Schenkman, 1983). Andre Donneur, “La politique du Canada face au terrorisme: un étude comparée,” in A. Macleod, ed., Lutte anti-terroriste et relations trans atlantiques (Bruxelles: Bruglant, 2006): 127-151. 14 This is one of the crucial insights found in the careful, empirical study by Daniel S. Geller and J. David Singer, Nations at War: A Scientific Study of International Conflict (Cambridge: Cambridge University Press, 1998), at 58. 15 One of the most important expressions of the idea that war occurs as a series of steps is John Vasquez, The War Puzzle (Cambridge: Cambridge University Press, 1993). 16 Power cycle theory was first articulated in published form in Charles F. Doran, The Politics of Assimilation: Hegemony and Its Aftermath (Baltimore: Johns Hopkins University Press, 1971). The understanding expressed in Midlarski’s writings that each of the members of the central system has an impact in dynamic terms on the leading state or states is crucial. Manus I. Midlarsky, The Onset of War (Boston: Unwin Hyman, 1988). 17 For a full explication of these concepts see Charles F. Doran, Systems in Crisis: New Imperatives of High Politics at Century’s End (Cambridge: Cambridge University Press, 1991). For a highlight of the key components of the theory, see Charles Doran, “Economics, the Philosophy of History, and the Single Dynamic of Power Cycle Theory,” Power Cycle Theory and Global Politics, International Political Science Review 24, 1 (2003): 13-50.

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resolution.18 Discontinuities in future security and foreign policy role shatter policy expectations. The singularity of major war associated with the passage of a state through a critical point on its power cycle is empirically demonstrable at a high degree of statistical significance.

In normal periods of history, statecraft is very much like chess. The number of principal actors in the central system is readily perceived. The relative power of each actor is known or can easily be estimated. Rules of the game of diplomacy are understood and largely adhered to. A concept of balance emerges whose limits are respected. Political stability midst structural change prevails.

But when a principal power passes through a critical point on its power cycle, and especially

when several states do so at about the same time in history (systems transformation), everything changes. The flat chessboard is now twisted and distorted. None of the prior assumptions about statecraft is sustainable: the number of principal actors is not known; the impact of the new relative power trajectories on long-standing foreign policy expectations is impossible to estimate; no one knows whether the prior rules of the game of diplomacy will be observed; balance arrangements are turned upside down. All is uncertainty. Such structural turbulence historically has elicited major war.

At the essence of this power cycle conception of world order is that war is a singular event, and

that it is the passage through critical points of radical structural change on the state power cycle which precipitates the conditions for major war. These same conditions are responsible for the emergence of alliance arrangements and for statistically significant differences in deterrence behavior.19 It is the precision of the theory, and its underlying plausibility in terms of the practice of statecraft, that lead to the ease with which the theory can be tested empirically and to the highly significant statistical results that reinforce its validity across more than two centuries of history.

Alternatively, instead of explaining war in terms of radical structural change at critical points on

the power cycles of states, the notion of power shifts attempts to locate the explanation for war in the long intervals located between the critical points. One advantage of this approach to war explanation is that most of history is located in these long intervals. By definition, critical points occupy comparatively short intervals of history. Longer intervals permit a greater opportunity for incidences of war to occur.

Likewise with the use of longer time intervals, less precision is needed in terms of the temporal

location of the drivers of war causation. Hence a greater variety of statistical technique and method of assessment is presumably available to the analyst.

Critical Points or Power Shifts?

According to the power shift literature, the explanation for major war lies in the general rise and

decline of states.20 It is the sweep upwards and the sweep downwards within the international system that

18 For an examination of the origins of different types of role differentiation and interaction with the power cycle dynamic, see William J. Lahneman, “Changing Power Cycles and Foreign Policy Role-Power Realignments: Asia, Europe, and North America,” International Political Science Review 24, 1 (2003): 97-111. 19 Daniel Y. Chiu, “International Alliances in the Power Cycle Theory of State Behavior,” International Political Science Review 24, 1 (2003): 123-136; Brock F. Tessman and Steve Chan, “Power Cycles, Risk Propensity, and Great-Power Deterrence” Journal of Conflict Resolution 48, 2 (2004): 131-153. 20 See for example some of the prominent discussions of the notion of the power shift in the quantitative, empirical literature: Woosang Kim and James Morrow, “When Do Power Shifts Lead to War?” American Journal of Political Science, 36 (1992): 896-992; DiCicco and Levy, “Power Shifts and Problem Shifts” (1999); Frank Whelon Wayman, “Power Shifts and the Onset of War,” in Jacek Kugler and Douglas Lemke, eds., Parity and War:

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causes war to occur. No differentiation occurs in terms of place in this rise and decline explanation. Nor is rise considered any more provocative than decline since they necessarily occur together.

On the other hand, if war causation within the power shift notion is restricted to “decline,” then

what is meant by decline becomes crucial to the argument. Is “decline” to be construed as decline in absolute power or in relative power? In dyadic analysis, these two concepts are identical because the decline of one state automatically means the rise of the other. Rise and decline are the exact inverse of each other when treated between dyads. Only when more than two states are considered interactively does the concept of “relative” obtain meaning that goes beyond what one could infer from absolute power scores. In this more complex dynamic context of a system, relative decline and absolute decline become truly delineated and convey very distinct meaning.

But even within the notion of relative decline, differentiation of important meaning persists. Is

relative decline to be thought of as a decline in level or decline in the rate? If the former concept of decline is adopted, such decline begins at the upper turning point on the state power cycle. But if the latter concept of decline is adopted, namely, rate of decline, the place where decline starts could be as early as the first inflection point on the power cycle or as late as the second inflection point, or anywhere in between. In practice, the proponents of the power shift argument do not observe these distinctions and instead associate declining power shifts with general movement downwards on the power cycle. Rate becomes incidental to level.

Some argue that proximity to a transition may create a greater likelihood of impact on war than

location elsewhere. Although this issue has been thoroughly examined in the transition literature, the debate continues. Regarding the impact of power shifts, some argue that proximity to a transition presumably is more important prior to a transition than after. One reason why location prior to the transition might be considered more important than location after a transition is that, logically, effects after the transition cannot be responsible for causing the transition itself. However, if fear of subsequent decline is the source of explanation, then a so-called subsequent effect (fear of anticipated decline) might act as though it has an impact on the incidence of the transition. But this hypothetical impact would only be causally relevant if anticipation of a transition is itself deemed theoretically possible. Many analysts question whether such anticipation of an event, in this case a transition, is theoretically or practically feasible, because forecasting such an event is so inherently difficult. Power cycle theory, for example, does not require the forecasting of a critical point as a condition of war explanation.

For purposes of this discussion, location near a transition in any case is moot. The matter of the

anticipation of a transition is not an issue here, since it is the overall thrust of rise and decline that for most writers is held to be the principal source of explanation for the onset of war in the hypothesis tested here, not a more time-specific accounting of power shifts.

If the argument is that power shifts, broadly defined and understood, are superior to critical points

as an explanation for war, then the logic of this assertion can quite easily be captured in a research design and submitted to quantitative, empirical test. Suppose as in Figure 1 that the argument is as illustrated. In

Evaluations and Extensions of The War Ledger (Ann Arbor: University of Michigan Press, 1996), Ch. 9, pp. 145-162; Steven Van Evera, “Power Shifts: Windows of Opportunity and Vulnerability,” Causes of War, Ch. 4, pp. 73-95; Jeffrey W. Taliaferro, “Realism, Power Shifts, and Major War,” Security Studies 10, 4 (Summer 2001); Dong Sun Lee, “Committing Suicide for Fear of Death: Power Shifts and Preventive War,” East-West Center Washington Working Papers, No. 6, September, 2006; Dong Sun Lee, Power Shifts, Strategy and War (Routledge, 2007); M. Taylor Fravel, “Power Shifts and Escalation: Explaining China’s Use of Force in Territorial Disputes,” International Security 32, 3 (Winter 2007/2008): 44-83.

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this sub-set of an idealized system of states, there are only two possibilities. One is the assumption that underlies the power cycle explanation for war. The other is the assumption that underlies the power shift explanation for war.

In the former understanding, war occurs as a result of passage through critical points of abrupt,

unanticipated change on the state power cycle where political uncertainty is enormous and the invitations to aggression and belligerency are substantial. So the critical points are the occasion for war.

Conversely, in the latter understanding, war results from generalized rise and decline of power

between the critical points on the comparatively linear segments of the power cycle. These segments thus separate the critical points. Moreover, since the line segment between critical points tends to be quite long, the temporal possibility is very great, one would think, that war will occur in one of these segments. Indeed, the probability of war occurring along these power shift segments of rise and decline ought to be far, far higher than in the much shorter intervals at the critical points. The power cycle interpretation is characterized by the incidence of upper and lower turning points and first and second inflection points. The power shift interpretation is characterized by the long non-linear time periods located between pairs of critical points.

Consider the following hypothesis and its null equivalent. H (1) Passage through critical points provides a more robust explanation than power shifts for the onset of war. H (0) Passage through critical points does not provide a more robust explanation than power shifts for the onset of war.

No amount of data would ever allow the analyst to prove a hypothesis directly and thus to accept that hypothesis directly. But a single test is sufficient to allow the analyst to reject a null hypothesis and, therefore, to accept its opposite, namely the hypothesis itself. That is the goal of the simple empirical test, carried out here, to determine which set of theoretical assumptions about war causation is the more plausible, the power shift interpretation, or the power cycle interpretation. Acceptance of the hypothesis favors the power cycle interpretation.

Operationalization of the Test

Of course, all prior tests of war causation comparing critical intervals and non-critical intervals

amount to a test of “critical points” versus “power shifts” and can be so expressed. But here we carry out an explicit test of the above hypotheses with the specific purpose of examining the power shift assumptions.21

In this test, two measures of major war are examined as the dependent variable. The first is

intensity measured in terms of the total number of casualties in war. The second is duration measured in terms of the length of war in days. Each of these variables is logged so as to normalize the distribution. The countries are those generally accepted as members of the central system for at least a part of the interval 1820-1997. Wars and war data are drawn from version 3.0 of the Correlates of War Inter-State War data set. Critical points are those calculated in Doran, 1991. A ten-year critical interval is calculated around each critical point to overcome the possibility of errors of estimate and data imprecision. The independent variable is binary and is coded in the following way. A state received a value of 1 if it was 21 Carried out by Jacob Heim, and directed by Charles Doran, this analysis appears in more extensive form in a forthcoming article by Jacob Heim.

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passing through a critical interval; wars occurring during these intervals correspond to the power cycle argument that the trauma of shifting tides at critical points on the power cycle are causally determinative of the major wars of history. A state received a value of 0 if it was not passing through a critical interval; wars initiated during these intervals correspond to the proposition advanced by the power shift argument that wars arise for the most part during the long sweep of state rise and decline irrespective of the trauma of structural change during a critical period on the trajectory of state rise or decline.

Interpretation of the Results

In the first regression run (Table A) examining the impact on war intensity, six of nine countries

had a statistically significant result with some 56 percent of the variance explained in the dependent variable. This means that six of nine countries when passing through a critical point had a statistically significant result at the 95 percent level in terms of the impact on war intensity. These countries were the United States, Germany, France, Japan, Austria-Hungary, and Italy. Overall, the null hypothesis that power cycle theory does not offer a more robust explanation than the power shift argument for the explanation of war can be rejected at the 99 percent level of statistical significance. The F statistic is 25.

A test of the same hypothesis using instead war duration as the dependent variable yielded similar

results but at a slightly lower level of variance explained in the dependent variable (34 percent) and level of significance. The United States, Japan, and China were statistically significant at the 95 percent level. With an F statistic of 10, the null hypothesis that power cycle theory does not offer a more robust explanation for the outbreak of war than the power shift argument can be rejected at the 99 percent level.

It should be noted that for several reasons these results are quite conservatively reported. (1) The

independent variable threw away a lot of information because of the coding rule using only binary data. However, as an initial cut, the results are highly significant even without exploiting the additional information that is available in the independent variable. (2) The approach employed here linearly approximates the function that underlies the actual data. Analysis that better captures the non-linearities in the power cycle would likely explain more variance in the dependent variable. (3) One critical point for Japan (its lower turning point upon entry into the system, which accompanied major war with Russia) was not included in the Doran list of critical points or in this analysis, slightly reducing the explanatory power of the critical points as a group. (4) The most important dependent variable, magnitude (number of states involved in a war x size of the state in power terms), was not used here because of the greater complexity of the calculation. Were this variable to be employed, the regression equations would likely yield better results because magnitude so effectively captures the theoretical conceptualization reflected in impact on major war, that is, the reality that it takes big states to cause big wars. Nonetheless, the results based on this preliminary analysis appear sufficient to reject the null hypothesis that power shifts better explain the origins of war than the power cycle explanation.

Comparisons and Contrasts

The power shift idea in its modern empirical form emerged in the aftermath of the tests

comparing critical points and transitions and the appearance of Systems in Crisis. If abrupt change on the power cycle could explain war, the argument sometimes heard, was why would not any trend or any change in trend do the same? Formal models looked at decision-making logic of rising and declining states without consideration of critical changes on those trajectories. The idea was that the trend itself could explain war. This is the logic of the argument, but what is wrong with the argument?

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(1)How is a trend or a change in trend to be defined? All trend alterations are not equal. Trends themselves come in different lengths and combinations. Theory has not guided definition. Definition is key to explanatory success.

(2) Decision-makers are adroit at coping with minor, or anticipated, trends or changes in trends.

Decision-makers must be able to cope with minor kinks in a trend line, or new trends, within a certain margin of variation in the course of the daily business of diplomacy. Therefore most trends and trend variations will be discounted and will not contain much impact on an event as serious as war.

(3) The reason a critical point explains war so effectively is that it is totally unanticipated (and

often counterintuitive, involving contradictions between the expectations of absolute power change and the associated relative power change), it is massive in terms of the structural changes from which it arises and therefore in terms of its impact on expectations and behavior, and it elicits over-reaction and belligerency on the part of governments attempting to react to the enormous political uncertainty that results. Across different data sets, temporal periods, and members of the system, the empirical results have been the same.22 This is because critical points tap the acceleration and deceleration of deep change in underlying structure involving all of the actors in the central system, or, when applied to a region such as the Middle East, all of the actors within the region, simultaneously and interactively. Most changes of direction in a trend, or trends in themselves, lack this potential for spectacular disruptiveness.

(4) Finally the concept of the critical point works because a critical point is imbedded in the

overall theoretical construct of the state power cycle and cycle of foreign policy role. All state power cycles and role cycles together compose the international system. Moreover, the power cycle and the role cycle are manifest in the asymmetric (second-order) logistic in which a critical point has a clear and interpretable mathematical meaning that accounts for the timing of war. This mathematical reality is the underlying international political reality with which the foreign policy decision-maker actually contends.

Reflections and Implications

We return to the theme that introduced the present paper. The problem for the power shift

hypothesis is three-fold. First, structural change in the system is just too abundant and diverse to enable general movement up and down the state cycles of relative power to be the primary source of explanation for major war. Common as war has been historically, there are too few examples of war and too many years of structural change for the power shift hypothesis to receive statistical substantiation.

Second, war is temporally specific. Structural change is not. If war is to be explained, that

explanation must capture the time-specific nature of war. When war occurs is not just a puzzle. It is the crucial question that valid causal analysis must be able to answer.

Third, if change in relative power is to be linked to the incidence of war, the relative nature of

power must truly be tapped. Dyadic measures of power are unable to do that because the increase of one state’s power is merely the decrease of the other state’s power. For genuine relativity to be tapped in the explanation regarding why and when war occurs, all of the members of the central system must be examined simultaneously to determine the contributions they make to structural change and to war causation. Only by including more than two actors in the analysis is relative power change truly relative (not just an inverse linear relationship between two actors).

22 Patrick James and Luis Hebron, “Great Powers, Cycles of Relative Capability, and Crises in World Politics,” International Interactions 23 (1997): 145-173.

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Power cycle theory offers both a time-specific explanation for when war occurs and a truly relative operationalization of power change that captures the abruptness of change at critical points of non-linearity on the power cycle. The abruptness of change at critical points in turn impacts sharply on perceptions of future foreign policy role. These are among the crucial reasons why the power cycle explanation continues to report such strong results concerning the origin of war in the modern state system.

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