Why Nations Fight: Past and Future Motives for War

There is a burgeoning literature on war and its causes. Almost all major studies approach the problem from a realist perspective.  They assume security is the principal motive of states and insecurity the major cause of war.  Realist theories elaborate mechanisms (balance of power) and conditions (security dilemma, polarity, power transition) that they consider responsible for conflict and war.

My dissatisfaction with the existing literature on war, and international relations more generally, was an incentive to write A Cultural Theory of International Relations (Cambridge University Press, 2008).  It develops a theory of international relations based on a parsimonious model of human motivation.  Following Plato and Aristotle, I posit spirit, appetite and reason as fundamental drives with distinct goals.  They generate different logics concerning cooperation, conflict and risk-taking. They require, and help generate, characteristic forms of hierarchy based on different principles of justice. A fourth motive – fear — enters the picture when reason is unable to constrain appetite or spirit. Fear is a powerful emotion, not an innate drive.  In real worlds, multiple motives mix rather than blend, giving rise to a range of behaviors that often appear contradictory.

In modern times the spirit (thumos) has largely been ignored by philosophy and social science. I contend it is omnipresent. It gives rise to the universal drive for self-esteem which finds expression in the quest for honor or standing.  By excelling at activities valued by our peer group or society, we win the approbation of those who matter and feel good about ourselves.  Institutions and states have neither psyches nor emotions.  The people who run these collectivities or identify with them do.  They often project their psychological needs on to their political units, and feel better about themselves when those units win victories or perform well. Transference and esteem by vicarious association are especially pronounced in the age of nationalism where the state has become the relevant unit.

I documented the relevance of the spirit for war in a series of case studies in A Cultural Theory of International Relations.  In Why Nations Fight, I extend my analysis to war throughout the modern era and analyze war initiation in terms of the relative power of states and their respective motives for war.  I constructed a data set of all inter-state wars involving great and aspiring rising powers from 1648 to the present. The data set identifies initiators of war (often multiple) ; their motives (security, material advantage, standing, revenge and domestic politics); the outcome (win, lose or draw); the nature of the rules, if any, governing warfare; the duration and intensity of the war; and the character of the peace settlement.

Contrary to realist expectations, I find security responsible for only 19 of 94 wars.  A significant number of these wars pitted great powers against other great powers and none of them were associated with power transitions.  This does not mean that security is unimportant in international affairs; it was a primary concern of all states who were attacked.  Material interests are also a weak motive for war, being responsible for only 8 wars, and most of those in the eighteenth century.  Security and material interest sometimes act in concert with one another and more often with other motives.  In some wars they are secondary to these other motives.  Standing, by contrast, is responsible for 62 wars as a primary or secondary motive.  Revenge, also a manifestation of the spirit, is implicated in another 11.  There can be little doubt that the spirit is the principal cause of war across the centuries, and that it and its consequences have been almost totally ignored in the international relations literature.

The character and robustness of domestic, regional and international societies and ideas about the efficacy of war determine the relative importance of various motives for war and its overall frequency.  Interest shows a sharp decline once mercantilism gave way to more sophisticated understandings of wealth.  Security-motivated wars show no similar decline by century but come in clusters associated with bids for hegemony by great or dominant powers.  The most recent clusters of security-related wars were associated with the run up and conduct of the two world wars of the twentieth century.  They were in turn a product of the dislocations brought about of modernization in an environment where great power competition and the drive for hegemony was conducted primarily by violent means.  Now that this era has passed in Europe and is receding in much of the Pacific rim, and hegemony achieved by force is now longer considered a legitimate ambition, the security requirements and fears of great powers should decline.

Wars of standing can also be expected to decline.  During the post-war era, and even more since the end of that conflict, war and standing have become increasingly disengaged in the sense that successful war initiation no longer enhances standing.  They may actually lead to loss of standing in the absence of United Nations’ approval of the military initiative in question.  The Anglo-American intervention in Iraq – a war in which territorial conquest was not an issue – is a case in point.  Changing values and norms encourage rational leaders to find other, peaceful ways of claiming standing.  To the extent that this happens the frequency of war involving either rising or great powers can be expected to diminish sharply.

Three shifts in thinking influenced the frequency of war and its motives. The first concerns the nature of wealth.  Until Adam Smith and modern economics, the world’s wealth was thought to be finite, making an increase in wealth for any state thought to result in a loss for others.  Once political elites learned that total wealth could be augmented by the division of labor, mechanical sources of energy and economies of scale, economic cooperation became feasible and increasingly important.  It all but put an end to wars of material aggrandizement among the great powers.

The second shift began in the nineteenth century and is about collective versus autarkic pursuit of security.  Alliances assumed new meaning at the Congress of Vienna as they had the goal of conflict prevention. Later congresses helped great powers ease regional tensions through agreements and moral suasion.  Following World War I, the League of Nations was given the more ambitious task of preventing war by means of collective security, but failed miserably.  The principle of collective security endured and thee United Nations, established in 1945, made it the principal mission of the Security Council.  The UN’s record is mixed, but the North Atlantic Treaty Organization (NATO) has been more successful.  It and other international groupings have played a prominent and arguably successful role in keeping the peace or terminating wars in the post-Cold War world.  Collective security has become the norm and an important source of regional and international stability.

The third and most recent shift in thinking concerns the nature of standing in international affairs. Historically, military success was the principal means of gaining standing and recognition as a great power.  There are other of achieving status within states, and the European Union, Scandinavia, Canada, Japan and Brazil all claim standing on grounds that have nothing to do with military might.  The more robust regional and international orders become the more multiple hierarchies of standing will also emerge at the international level.  States will feel more confident about seeking standing in diverse ways and devoting resources toward this end that might otherwise be reserved for the military. BBC World Service polls consistently indicate high standing for countries associated with alternate visions of the international system.  When asked what countries exerted a positive influence in the world, Canada and Japan routinely top the list, followed by France, Britain, China and India.

If peace continues among the major powers, claims for standing on the basis of military power will become even less persuasive.  As standing confers influence, states will have additional incentives to shift their foreign policies to bring them in line with the dominant incentive structure.  In such a world states would view even more negatively the use of force in the absence of unqualified international support.  From the vantage point of say the year 2030 we might look back on the Iraq war as one of the defining moments of the international relations of the twenty-first century because of the way it delegitimized the unilateral use of force and foregrounded and encouraged alternative, peaceful means of gaining standing.

The three shifts in thinking I identity have two common features.  Each developed slowly and progressed in fits and starts.  Changes in beliefs took a long time to become sufficiently widespread to affect practice and practice was at first halting and unsuccessful.  Over time, however, patterns of behavior changed and the motives in question become increasingly disaggregated from war.  The revolution in thinking about wealth began in late eighteenth century, did not fully become the conventional wisdom until the late nineteenth century and did not act as a check on war until at least a half-century later.  Collective security, a product of the early nineteenth century, took almost 150 years to show meaningful political consequences.  Shifts in thinking about standing are a twentieth century phenomenon and only began to affect political practice during the Cold War.

The third shift, that I am trying to encourage, concerns standing.  Iraq and other recent wars indicate the extent to which war undermines standing unless it is carried out with the authorization of appropriate international organizations for purposes considered beneficial to regional or international communities.  The sooner more policymakers grasp this truth, the more the frequency of war will decline.

I can only hope that research that demonstrates how traditional conceptions of standing have been responsible for war can help accelerate this change and with it, the search and acceptance of alternate means of claiming and receiving standing.


Richard Ned Lebow is Professor of International Political Theory at the Department of War Studies, King’s College London and James O. Freedman Presidential Professor, Emeritus, Dartmouth College

Further Reading on E-International Relations

Please Consider Donating

Before you download your free e-book, please consider donating to support open access publishing.

E-IR is an independent non-profit publisher run by an all volunteer team. Your donations allow us to invest in new open access titles and pay our bandwidth bills to ensure we keep our existing titles free to view. Any amount, in any currency, is appreciated. Many thanks!

Donations are voluntary and not required to download the e-book - your link to download is below.


Get our weekly email