Most wars have been irrational in terms of means or ends or both together. This is because choices for war are influenced by emotions, ideologies, domestic politics, and the tyranny of history, as well as by the more rational pursuit of material and strategic interests. Decisions for war have been almost invariably made by a handful of rulers and their advisors and entourages, and this is as true of democracies as authoritarian regimes.
The evidence for these propositions comes from quantitative research on modern wars, and from my own sample of long-run sequences of war across history: in the Roman Republic, ancient and imperial China, Japan from feudalism to 1945, Europe over a millennium until today, pre- and post-colonial Latin America, and the United States from the Civil War to today. There are four main types of war which we find in all periods and all regions of the world: in-and-out raiding, war to effect regime change abroad, war to conquer and rule slivers of border territory (which are often “revisionist” wars), and war to conquer and rule over territorial empire. These all have distinctive characteristics.
Why do rulers choose war to achieve ends rather than relying on softer sources of power—economic exchange, cooperative ideologies, or geopolitical diplomacy. Choice is not quite the right word, since decisions also embody social and historical constraints of which the actors are not wholly aware, constituting part of their taken-for-granted reality. Humans create social structures, but then these become institutionalized, constraining subsequent action. Wars must be studied not merely as individual cases to be fed into quantitative models, but as historical sequences of purposive action. War and peace decisions are influenced by constraints inherited from the past, and these tend to involve several non-rational elements. National “caging” produces ignorance of the values and capacities of foreigners. Also involved are emotions, ideologies, domestic politics, and a militarism which is often already “baked in” to culture and institutions.
Some rulers have tried hard to calculate the pros and cons of wars, but miscalculations occur too often to support a rational-choice model.Through history to today rulers launching offensive wars win them about 50% of the time—very poor odds if one is sacrificing many thousands of young men in pursuit of victory. Most of the offensive wars that go according to plan are imperialist wars, where sharks attack minnows. But even these aggressors often underestimate the resolve of minnows defending their homeland, and of allies who might spring up to defend the supposed minnow—Putin’s Russia being the latest example.
Some victors have conquered empires, creating what they and we today call “civilizations,” for almost all so-called civilizations were achieved by conquest. The winners of wars left the records from which we write history. In contrast they destroyed their victims’ records, and so the losers of wars have mostly vanished from history. We know much about Rome, but very little about Carthage. Thus, victory in war is seen as commoner, more profitable, more rational, and more glorious than it really was. Wars in self-defense are generally considered as rational and legitimate. Some are. But in many cases submission would have been more rational. War rarely pays, for all sides lose where it involves costs greater than its spoils can justify, where there is no clear winner, or where war does not resolve the dispute in question. These constitute the majority of wars. Imperial wars of conquest did usually benefit the victorious rulers and attendant merchants, bankers, settlers, clerics, and officials of empire—but few wars of conquest benefited the colonizing people as a whole, and almost none benefited the conquered, exploited, enslaved, or exterminated Indigenous Peoples.
War pays us back more swiftly for mistakes than any other human activity, and humans are not efficient calculating machines—more’s the pity, since peace is more rational than war. If the social world did conform to Realist theory, and if rulers did carefully calculate the costs and benefits of war, trying hard to set emotions and ideologies aside and ignoring domestic lobbying pressures, they would see that most wars are inferior to economic exchange, the sharing of norms and values, and diplomacy as ways of securing desired goals. Realism is fine as a normative theory, showing how rulers should act for maximum benefit, but it is not a description of reality, for they do not act in this way. We need more Realism, for this would bring the benefits of peace!
War is the least rational of human projects. Rulers are asked in matters of war and peace to make decisions with momentous consequences, armed with sketchy information, ideologies and emotions induced by their imprisonment within their own society amid anxiety-producing, unfolding environmental and geopolitical constraints, and the tyranny of history. The task of surmounting this is often beyond rulers, as it would be beyond us, too. Human beings are not genetically predisposed to make war, but our human nature does matter, indirectly. Our tripartite character, part rational, part emotional, part ideological, when set inside the institutional and cultural constraints of existing societies, makes war a persistently catastrophic outcome.
It is possible to generalize about wars since they have changed much less than is generally thought. True, the weapons of war have become exponentially deadlier. Indeed, in very recent times some of the available weapons are far too deadly to be ever usable for any rational purpose. But the surprising fact is that the fatality rate in battle has barely increased through history. This is because soldiers adapt to new weapons. They no longer stand upright in battle. Instead, they shrink down into holes in the ground, trying not to show themselves over the parapet of their trenches. Aerial bombing has become the main modern cause of death, especially of civilians, and that is obviously novel. But in the past civilians also suffered many casualties. For example, they were usually massacred if their city had not quickly surrendered to the conqueror.
Throughout history, soldiers have shared many of the same experiences. They have arrived in battle in good spirits, confident of victory and a swift return home. But this turns to terror as the horrors of their first battle hit hard. Then they become cautiously inured to the enduring risk, hating “hero” comrades who draw fire onto themselves. Finally, fear returns, and they become near-useless in battle.
There are many traditional features of the war between Russia and Ukraine. This is an ambiguously revisionist war, perhaps aimed only at slivers of border territory, perhaps at the absorption of all of Ukraine into the Russian empire. The Russian aggressor seeks to recover “lost territories” that used to belong to Russia. Most Ukrainians dispute this, seeing the same territories as their homeland. Thus, both sides claim the moral high ground, which is reinforced for Putin by his plausible claim that NATO had been provocatively expanding up to Russia’s borders. It is of course more difficult to end wars when both sides strike such moral stances. Putin, trapped within his national cage, grossly underestimated the determination of Ukrainians to defend their homeland as well as NATO’s willingness to aid them—another example of nationally caged miscalculation. Westerners denounce the terrors of Russian bombing of Ukraine’s cities and civilians. But this is exactly what the US and Britain had perpetrated against German and Japanese cities in World War II. It is normal in modern wars, just as sacking cities, and slaughtering the inhabitants had been in earlier centuries. Putin is not uniquely incompetent or evil. Our leaders also lack competence in war, and war itself is evil.
Michael Mann is Distinguished Research Professor of Sociology Emeritus at the University of California, Los Angeles, and Honorary Professor at the University of Cambridge. He is the author of the award-winning book series The Sources of Social Power and of Incoherent Empire, Fascists, and The Dark Side of Democracy: Explaining Ethnic Cleansing. He lives in Venice, CA.