With the patient brutality of a beating by mobsters, artillery shells fell one by one into the old city of Dubrovnik. The streets, once busy with citizens and tourists, were strangely quiet in November 1991, aside from intermittent explosions and the occasional crack of sniper fire. Dubrovnik's citizens huddled in their cellars and talked about their enemy, the Serbs. 

"I have stones," a Croatian sculptor told a reporter. "I think I could throw them on their heads. I was a kind of pacifist. Never hated anybody. But now?" 

People reading the news in Western Europe and America, people who perhaps had only recently come to view Dubrovnik's picturesque streets and massive city walls, could scarcely believe that it was all being battered into rubble. A war between Communist nations would not have surprised them. But this fight had begun after both sides, Serbia and Croatia, held free elections. Somehow a war between democracies seemed horribly wrong. 

When Eastern Europe began to turn toward democracy back in 1988, news analysts said the risk of war in Europe was "of course" diminishing. As the Soviet Union also stumbled toward democracy, then "of course" at each step the Cold War dwindled. The democracies would "of course" be good friends even with a nation like Iraq if only it were a democracy too. When troubled nations from Nicaragua to Namibia held free elections, the U.S. government drew back from intervention. Everyone from American presidents to Russian peasants spoke as if increasing democracy must decrease the risk of warfare. 

Do democracies really tend to maintain a mutual peace? Or is this a delusion that will endanger any nation so foolish as to trust it? The only way to answer this important question is to look at history. 

Dubrovnik is a good place to start. A dozen centuries earlier, when it began to build its mighty walls, the city had needed them for survival. It was an independent republic (named Ragusa) where citizens elected officials and voted in councils, generation after generation, obedient to a carefully crafted constitution. They modeled their regime on Venice, another stable republic--and a great enemy. Bitter competitors for the thriving Adriatic trade, the two merchant cities called each other evil names and now and then found a legal pretext to seize a rich galley belonging to their rival. Yet never once did the republics make war on each other. And down through the centuries, as a hundred wars tormented the region, Ragusa never made war on any other solidly established republic. For that matter, neither did Venice. 

That surprising stretch of peace is only one of many such cases that turn up in odd corners of history, wherever there were republics. When states avoid war so thoroughly, can that be a mere accident, or is there some deeper reason? If a general reason exists then we may already have at hand, in peaceful democratic regions like Western Europe, the blueprint for a solution to the problem of war. 

Such a solution becomes more essential every year. All sorts of nations are learning to build nuclear weapons. Still more unspeakable devices will someday be easy to make, in the zone where microelectronics and biochemistry are converging. Sooner than many people think, any substantial fragment of a nation will be able to do to any city in the world what the Serbs did to Dubrovnik. In the long run we may not survive unless we avoid all wars--not just among some states, but among all of them; not just for the next couple of decades, but for all time. What international order can achieve so much? 

The ideas that have guided international policy for generations are bankrupt. Few believe any longer that we will create an overarching world government, under the United Nations or any other organization, that will prevent wars through its own unified rule. Policymakers have fallen back on a traditional answer, the balance of power. They propose to deter war by mustering invincible coalitions of nations to oppose anyone who threatens the status quo. But the failures of that policy litter history. Wars in the Persian Gulf and Bosnia are only the most recent of a thousand examples. 

Almost in desperation we turn to the claim that free peoples will not make war on one another. This idea had been developed by 1785, when there were scarcely any democracies in existence, by the great philosopher Immanuel Kant. A world where every state was a democracy, he wrote, would be a world of perpetual peace. Free peoples, Kant explained, are inherently peaceful; they will make war only when driven to it by tyrants. 

Kant was wrong. Democratic belligerence is such a pervasive problem that we find it wherever democracies have existed. For example, as early as the fifth century B.C., the rocky coast where Dubrovnik now stands was the scene of deadly quarrels involving free governments. Already people of the region were sending envoys abroad to make impassioned pleas for help to fight their enemies. Corinth, a Greek republic, seized the chance to take control of a coastal town. Corcyra, a nearby island democracy, took offense and went to war. Before the affair ended the rocky Adriatic shores were littered with shattered ships and the pale corpses of sailors. That is all ancient history, but it is a good demonstration that war will not be restrained by an inherent peacefulness of ordinary citizens. In our own times, democracies have burned people to death by the tens of thousands in the fires of Hamburg and Hiroshima. 

Yet in all these wars, one side fell short of what most people would call democracy. The United States, as will be discussed later, never has fought a democratic government basically like its own. Neither did ancient Corcyra; its enemy Corinth was governed by an oligarchic elite that scarcely allowed more freedom to common people than did the elite who led Japan in the 1930s. The governments of Serbia and Croatia in 1991, although elected, were hardly democratic (I will get back to this later). Somewhere there is a line that divides genuinely democratic regimes from those pervaded by authoritarian ways. This line has been a line of battle time and again through history. 

Can it really be true that genuine democracies, however readily they attack other types of regimes, do not make war on their own kind? Even if they have never done so in the past, is that owing to any solid reason that will reliably restrain them in the future? And if there is such a reason, can it teach us anything general about how in general to conduct international relations in this world where many regimes are far from democratic? 

These questions can be answered with the evidence of history. In this chapter I briefly review previous work on the subject and describe my own methods for approaching it. Then I summarize the chief results that are worked out in the rest of this book.

Are democracies more peaceful than other forms of regime? Beginning in the 1960s, scholars devoted thousands of hours to analyzing wars statistically. For a long time they failed to find any general rules. On the whole, democracies were embroiled in wars nearly as often as any other type of regime. In fact, hardly anything seemed to have a major influence on the likelihood of war--not a nation's domestic situation, nor its economic position, nor its ideology, nor any other obvious characteristic. Until scholars looked at the two rival regimes as a pair, they failed to clearly demonstrate any influence of democracy. 

Yet several scholars (including me) did notice, independently, a peculiar regularity: during the past century there have been no wars between well-established democracies. The first articles on this were scarcely noticed, but gradually a few political scientists took up systematic study. Their findings remained almost unknown outside academic circles. After all, there were obvious objections. Critics pointed out that there were only a few dozen full-fledged democracies in the world, and most of those had not been around long. Maybe they just had not yet happened upon reasons to fight one another. Or maybe the absence of wars between certain nations was not attributable to their democratic nature at all but to a specific level of capitalist economic development, international trade, or the like. 

Scholars had meanwhile compiled lists of the hundreds of conflicts of the past two centuries, assigning numerical codes to sizes of battles and degrees of electoral freedom and so forth. At first only one scholar, R. J. Rummel, approached these with an eye to the question of wars between democracies, compiling data and applying rigorous statistical tests. Gradually he was joined by Bruce Russett and others who confirmed and extended the findings. What was the probability, they asked, that the absence of wars between well-established democracies is a mere accident? The answer: less than one chance in a thousand. That is a level of certainty not often achieved with laboratory rats, let alone in studies of international relations. 

These studies ruled out out the most obvious objections. They showed convincingly that the lack of wars between democracies is not an artifact caused by the limited number of such regimes--there have been more than enough to provide robust statistics (even if the democratic alliances of the Cold War are left out). It is not because of the geographical distribution of democracies--they are found mainly in Europe, hardly known for its shortage of wars. It is not because of their advanced economic development--wealthy countries fight wars about as often as poor ones. These and other variables, from alliance structures to trade relationships, certainly influence whether nations will go to war, but none have been found useful in explaining the consistent peace between democracies. Some political scientists now feel that, as Jack Levy wrote, "this absence of war between democracies comes as close as anything we have to an empirical law in international relations." 

Others remain skeptical. The data on modern democracies are skimpy, and they tell us nothing useful about territory outside the North Atlantic region from the United States to West Germany, the only area where democracies have a long and varied record. Worse, it is far from clear just when we should or should not call a regime a well-established democracy; it seems that in each particular case, scholars defined the regime according to personal taste. Perhaps the strongest objection to the idea that democracies are inherently peaceful is that it does not fit comfortably with other beliefs that many people hold about the way nations behave. We cannot feel confident about a statistical "law" until we understand the reasons behind it. "Nobody has much idea why this relationship exists," one scholar complained. 

This is not for lack of theories. Particular cases of peace have been explained by the international configuration of the times (as democracies kept peace with one another in 1945-1990 while allied against the Soviet Union). I address this idea in cases where it arises (chapter 14, for example), but we will find that peace among democracies has been too widespread for such special explanations to work everywhere. That leaves explanations based on the internal characteristics of democratic nations. The possibilities include almost every kind of psychological, cultural, social, economic, or structural feature. I give a quick overview here, reviewing the main alternative explanations more closely in connection with particular cases (especially in chapter 3). 

The explanations are usually separated into two categories: one centered on "structures" and the other on "norms" or, more generally, "culture." 

According to the first type of explanation, democracies might keep mutual peace because of something in the structure of their governments or of their entire societies. In particular, perhaps (1) constitutional checks and balances tie the hands of a leader who would hurl a nation into a needless fight. Or perhaps (2) the whole complex structure of democratic civil society constrains the government. Or perhaps (3) democratic nations, associated through international capitalist networks, find more profit in trading than fighting. 

Alternatively, democracies might maintain peace because of something in the way their citizens think about things: their norms for behavior, their values and beliefs, their cultural traditions in general. In particular, perhaps (4) the common people, who in a democracy are able to hold back leaders, do so out of fear and horror of war, seeing little to gain from a fight. Or perhaps (5) the public holds back leaders from war because ordinary people think it disgraceful to attack people like themselves, citizens of a fellow democracy. Or perhaps, more subtly, (6) the leaders of democracies themselves are accustomed to negotiating and making compromises, whereas the sort of people who become tyrants are hungry for battle. 

Or perhaps the answer lies in some combination of explanations. The structural and the normative cannot be neatly separated, for they are only two ends of a spectrum of human forces--at one end collective and formalized, at the other end individual and internalized. These forces interact promiscuously. Courts of law and legislatures work hard to shape public ideals of behavior; reciprocally, if people did not hold particular ideals about what is proper, their institutions would be different. 

The job, then, is to disentangle the structural and cultural influences, to find which weigh on decisions about war or peace so as to inhibit war between democracies. Such a study requires a large and diverse body of historical evidence. I take up the task in this book--the first to attack the question of democratic peace comprehensively from the historian's standpoint, sifting every land and century for relevant evidence. 

We cannot study wars between well-established democracies, for no such wars have existed. But we can look through history for whatever conflicts have come close. There were confrontations in which democracies deployed military force against one another, although they did not quite go to war. And there were wars between regimes that somewhat resembled democracies. 

For example, Britain and France came close to battle in 1898 over the outpost of Fashoda on the Upper Nile. And in 1954 the United States covertly supported an armed raid that brought down the democratically elected government of Guatemala. These events were not wars, but they were close enough to make us wonder what was going on. Looking further back, we find outright wars between the French and the Roman Republic in 1849, between the Americans and the English in 1812, and so on back to the ancient Greeks, all involving regimes that had at least something in common with modern democracies. Even the most remote cases have something to tell us, if peace among democracies is truly a universal phenomenon with a deep explanation. 

I therefore compiled a list of borderline cases--crises in which regimes resembling democracies confronted one another with military force. After sorting through counterexamples proposed in the political science literature, plus discussions with scholars and my own research into over a thousand works by historians, I believe that the list is essentially complete. Even stretching terms like "war" and "democracy" to unreasonably broad definitions, it turns out to be a much shorter list than one might suppose--of the tens of thousands of recorded armed confrontations between regimes, barely three dozen cases fall into this category, including some quite trivial and unlikely ones. They are listed in the appendix. 

Lists of crises have also been assembled by political scientists, who dissect them with statistical tests. These tests are powerful tools, but some things (especially in the "cultural" sphere) are hard to reduce to numbers. Nevertheless, in the following I refer to these studies, and also to related statistical investigations by anthropologists and social psychologists, which draw on data entirely different from mine. The results all tend to confirm the ideas I present--no accident, for I gave up any ideas contradicted by solid studies. Some of the confirmatory statistics that I mention only briefly represent years of scholarly effort. 

Here I follow a procedure that avoids statistics: comparative case study. In this well-tried method, selected events are investigated with the tools of the historian until the peculiarities of each situation are understood. The method requires asking the same set of questions for each ease and comparing the answers. For a given crisis between two regimes, I ask: (1) How far did they proceed toward war? (2) What particular features of each regime were or were not fully democratic? From crises that at first seem kaleidoscopically diverse one can hope to sift out a set of features that vary in strict relationship with a regime's decision to make war or avoid it. 

Most comparative studies look at a sample of all cases, but conflict among democracies is so rare that I have been able to include virtually every significant crisis relevant to our inquiry. A typical social science study would proceed by using features of regimes to sort the regimes into categories (defined according to a preliminary theory); then it would count the percentage of regimes in a given category that acted in a given fashion. I have instead found features that let me classify regimes in categories that give essentially 100 percent results--all or nothing. This is a , hunt for truly general "laws" of history. Most historians and social scientists would call such an enterprise quixotic, and almost always they would be right. However, I am trying to study only the most deadly conflicts between certain types of regime. In this particular subject, one can turn up more consistent laws of behavior than anyone (including me) would have guessed. 

Certainly there are cases that at first glance scarcely fit any law of democratic peace: the cases gathered in the appendix. Such exceptions can be used to prove a rule, in an old sense of "prove"--to probe the rule, to test it, to uncover its limits and its essential nature. In ambiguous cases, where affairs are most delicately balanced, the underlying forces at work become especially visible. In the method of comparative case study, apparent exceptions can help us to pin down exactly which features sort regimes into categories in such a way that their mutual peace obeys general rules. 

Nobody could do original historical research work on so many diverse cases, and I have relied on historians who have specialized in the various periods. I consulted at least five works even for the most trivial crisis, and usually dozens. Some cases, however, historians have never studied with my questions in mind, and I had to go back to primary sources (which meant reading French, German, Italian, Tuscan, and Spanish, plus a bit of Alemannic, Greek, and Latin). It was startling how often these sources cleared things up: people of the time were acutely aware of connections between war and democracy that later scholars overlooked. 

Space constraints allow me to present only a small fraction of the evidence I have found. Any crisis involves thousands of events and decisions, but I relate only a few representative ones. Specialists may find the omissions and simplifications unforgivable, but I do not think that more extensive inspections would weaken my conclusions. Nowhere do I dispute what is accepted by specialists, and where they disagree I have always found enough common ground to address my question about the relationship between democracy and war. 

But when people say "democracy" and "war," what exactly do they mean? The definition of such terms is no dull formality. Definitions that divide groups into categories are the backbone of comparative case studies. The quest for categorization leads us to inspect a fabulous zoo of political communities, the more strange and remote from our own the better. As an example and a first step, let us look not at wars but at something still more puzzling: unbroken peace, in the most unlikely places and times. 

For centuries the Swiss mountain communities were only vaguely aware that they had any special political character. Everyone accepted the principle that communities should be subject to a feudal lord, in a hierarchy of nobles that extended up to the Holy Roman Emperor. Yet when one of these lords levied an unpopular tax or appointed an unpopular official, the Swiss would argue endlessly while quietly running their own affairs. Such resistance had not brought much conflict when these were bands of impoverished cowherds. But with the booming new trade through the mountains, princes began to attend to their rights over toll and tax. Certain lords assembled their knights and rode into the forests to teach their obstinate subjects a lesson. Instead they learned one: commoners in rugged terrain, standing alongside their neighbors to defend their freedom, can shatter cavalry. From the mid-1300s we can regard some of the Alpine communities as independent states, acknowledging overlords in principle but scarcely in practice. 

There were not a few of these little Forest States. The first independent ones called themselves Uri, Unterwalden, and Schwyz (which would eventually give its name to all of Switzerland). Later came others, such as Appenzell and the remote Gray Leagues, making nine distinct states in all. Each ran its affairs independently; usually each had its own flag and coinage. They combined with one another in a variety of pacts, but for the most part each state could and did govern itself and go to war all on its own. 

These Swiss "cantons" did not have the rigorous governmental machinery of the modern nation-state. Yet they had enough government to make sure that the quarrels of clans and factions never went beyond minor brawling. In these heights, where early in the afternoon the cold shadows of mountains settled onto the valleys, the people of a village had to cooperate or perish. It was the community as a whole that managed the irrigation ditches and pastures scattered among the pine forests. 

Since time out of mind, the men of a given district had gathered in a meadow one Sunday every spring. These were the most ordinary of people, but they felt entirely competent to speak their minds and elect their leaders and judges. When foreign affairs pressed they would assemble more often, listening to envoys and settling policy by majority vote. 

Of course these were not democratic states in the modern sense. After the assembly the men would disperse to spend the summer in high meadows with their cows; they then passed the long winter closed in wooden huts. Effective government of the district meanwhile rested in the hands of a few wealthy and respected families Who had time for it. Yet these families were no distinct oligarchic elite. Basic policy was settled in open debate where almost every man had an equal right to argue and vote. Through a half-dozen centuries the Alpine valleys constituted a laboratory of independent states that we may tentatively call well-established democracies. 

Not once did any of the Swiss democracies make war on another. This was not because the men of the Forest States were particularly peaceful. Time and again they shouldered their terrible halberds and trudged off to battle a nearby feudal lord, the duke of Milan, the duke Of Burgundy, the king of France, or the Holy Roman Emperor himself--and usually beat them. Nor did the Forest States maintain mutual peace because they were culturally similar and had common interests. In a world where peasants from Britain to Japan habitually gathered under the command of their lords to slaughter their nearest neighbors, the Swiss restraint was a phenomenal exception. Such a durable success in maintaining peace must have something to teach us. 

If this were a unique case it could be brushed off as a freak occurrence, but the Swiss democracies were not quite alone. At the other end of the Rhine lay a terrain the opposite of Switzerland's: the flat lush meadows of Flanders, dotted with sheep, and here and there with industrial cities whose winding streets clattered with the sound of a thousand looms. In the early 1300s craft guilds seized power in Ghent, Bruges, and Ypres; now commoners down to the poorest weaver or baker helped elect officials. Historians have called these governments, with many qualifications, a sort of democracy. 

From the chaotic history of Flanders I extract one important fact. Although these cities had long been bitter commercial and military rivals, once they became quasi-democracies there was no war whatsoever among them. The Flemish kept this up for only half a century, however, before they fell under the control of autocrats; then with scarcely a year's delay the cities took up their old practice of battling one another. In short, looking at Switzerland and Flanders together, we see that the connection between democracy and mutual peace is not a purely modern affair. Regimes could be far from modern democracies yet still reliably maintain peace with their own kind. If we aim to understand that fact, we must try to define "democracy" broadly enough to include these regimes. 

To define "democracy" I will begin with a more general concept--the "republic." The old dictionary meaning of the word gives us a start: in a republic, political decisions are made by a body of citizens who hold equal rights. Many political scientists see the crucial feature of these rights as "public contestation" over choices, with leaders held accountable for their actions. In all such republics the citizens vote to select and remove officials and otherwise set policy, either directly or through representative councils; in all there is freedom of political expression and association, toleration of politically dissenting minorities, and the rule of law. 

A lot is packed into that last sentence. Different scholars make up the list of key features in their own ways, but any brief list like this will do, simply to illustrate what "equal rights" to participate in "public contestation" means in practice. 

Not all republics are democracies. The body of equal, voting citizens may constitute only a small fraction of the population. In Switzerland, for example, alongside the mountain democracies there were urban republics where only a thousand or so property owners participated in elections. By the traditional dictionary definition, a democracy is a republic in which "the people" comprise the body of citizens. This "people" is never the entire population, and the name "democracy" has normally been applied even to regimes that denied the vote to women. If required to put the definition in a simple form that fits with common usage, I would begin by calling a republic a democracy if the body of citizens with political rights includes at least two-thirds of the adult males. I explore the workings of this definition more closely in subsequent chapters, beginning in chapter 2 by reaching back to ancient Greece. 

The other type of republic is oligarchy. In these regimes an entrenched elite rules over a large body of people who are part of the core life of the community--peasants, for example, or blacks until recently in South Africa, or (as we shall see in chapter 2) most of the population under many ancient Greek regimes. As a starting point, I would call a republic an oligarchy if fewer than a third of the adult males hold political rights. That leaves in question regimes in which between one-third and two-thirds of the men were voters, but these have been rare in history. Eventually I supply a definition that covers every case (chapter 7), but for most purposes the crude count of voters suffices. 

The main alternative to republics, of course, are autocracies, shading off into authoritarian regimes, such as military juntas and pseudo-republics with sham elections. Another alternative is a regime in which the central government is nonexistent or counts for little, as seen in many tribes, some medieval communities, and Somalia, Afghanistan, and the hinterlands of Colombia and Cambodia in the 1990s. This is sometimes called "anocracy." I explore the borderlines more closely in later chapters, but in practice most regimes can be quickly classified as either thorough republics or something far different. In the overwhelming majority of cases the answer is obvious to anyone who takes a good look--foreigners, the populace itself, or later historians. 

The other term that must be carefully defined is "war." This phenomenon is usually only too obvious, but here also it will repay us to inspect ambiguous cases. 

Consider, for example, a crisis in Switzerland in 1490. The instigator was the abbot of the monastery of St. Gall, the theocratic ruler of a mountain territory. He had persuaded democratic Schwyz and other neighboring Swiss states to join him in what seemed an innocuous defensive pact. The pact became a problem when peasants under the abbot's authority resisted his tyrannical rule, and the citizens of nearby Appenzell took up arms to help their fellow peasants win liberty. Other Swiss democracies felt bound by their oath to support the abbot's traditional rights; they declared war and sent an army. The outnumbered Appenzellers held back sullenly behind their frontier, and the rebels of St. Gall gave in without a fight. This paltry and bloodless affair would scarcely be worth mentioning, except that it was the only occasion that I have uncovered between 362 B.C. and 1847 when democratic states confronted one another in arms. 

The St. Gall conflict hardly seems to qualify as war. But where should we draw the line? One satisfactory definition of war is violence organized by political units against one another across their boundaries. For this study I set the level of violence to include any conflict involving at least two hundred deaths in organized combat. I give further examples of not-quite-wars between democracies in chapter 2 and later chapters. 

First is an observation only slightly different from what others have reported: Well-established democracies have never made war on one another. I defer considering a few ambiguous cases by insisting that democracies be "well established"--I clarify what this means as we look through the possible exceptions. The only new feature of this statement is that it does not explicitly or implicitly specify "modern" democracies. The statement applies to dozens of earlier regimes that have scarcely been studied in this context. 

In the vastly distant society of ancient Greece there were a number of democracies, by my inclusive way of defining the term. In chapter 2, I review their history and find not a single unambiguous case of Greek democracies warring on one another. The surviving evidence is so meager that we cannot be sure, yet it is remarkable that no clear-cut example can be found during nearly three centuries of democratic regimes--a period during which we know of many undoubted wars between these regimes and oligarchies or monarchies. Another half-dozen communities that have usually been called democracies were the Forest States of medieval and early modern Switzerland; these definitely never warred with one another. It is surprising that scholars have failed to notice the absence of wars among the Greek and Swiss democracies as well as modern ones. Any rule that holds in such an extraordinary variety of societies should have a correspondingly general explanation. 

The search for explanation is advanced by a second result, wholly new and unexpected: Well-established oligarchic republics have scarcely ever made war on one another. Almost as completely as democracies, oligarchic republics have historically kept peace with their own kind. For example, in Germany more than seventy autonomous Hanseatic city-republics maintained absolute peace among themselves for three and a half centuries, even as they battled every neighboring autocrat. Oligarchic republics may not seem relevant to modern history, where only a few are found. Yet their amazing success in maintaining peace deserves our respect and attention. 

This record imposes severe limits on explanations for republican peace. Oligarchic republics have warred abundantly with every other type of regime, including democracies. Peace has prevailed only between the same kinds of republics, oligarchies or democracies, as the case may be. This pattern of war and peace undermines explanations that invoke formal constitutional structures. Oligarchic republics, just like democratic ones, have traditionally had an elaborate array of formal structural checks on policy decisions, yet that has not kept them from fierce wars with democracies. Explanations that invoke domestic or international economic and social structures run into much the same difficulty. At any rate, purely economic or social explanations must be strained to cover societies as radically diverse as ancient Greece, medieval Switzerland, and our own. 

A better explanation may be found by turning to the few exceptional cases in which republics did confront their own kind in arms. Whatever it is that normally prevents such conflict must have been weak or absent here. I learned about this especially in the history of Italy up to the Renaissance, a laboratory of wars fought by every variety of regime including cities resembling oligarchic republics. These cities often fought one another--leading to the only substantial set of wars that I have found among apparent republics in any historical locale. In chapters 3 and 4, I review the Italian history and find a striking regularity. The city-republics entirely ceased fighting one another in the latter 1300s, although they continued to battle cities ruled by autocrats. What was the changed factor that brought peace? We shall see that the cities before the change had an anocratic character, resembling that of primitive "tribal" regimes--a type of "democracy" that does war on like regimes. Evidence from anthropology as well as from the Italian and other historical cases shows that a condition for republican peace is th existence of governments that can keep private feuding from spiraling into group warfare. When I say peace among "republics," then, I mean among republican territorial states. 

The early Italian cities had formal constitutions with voting councils. These did not keep peace until people became obedient to the structure, putting their trust in law rather than private vendetta. So we should look beyond structures to norms, and in particular to political culture. 

In chapters 4 and 5, I take up this slippery subject. "Political culture," however it is defined, at a minimum includes some set of beliefs about political action--beliefs about how people ideally ought to deal with one another, and beliefs about how they really do deal with one another in practice, when groups are in conflict. These beliefs are inseparably linked with customary practices and formal institutions. But in the narrow sense of the term, political culture stands near the normative end of the spectrum of human forces, among private values and expectations. 

What makes a political culture republican? One key element, tied up with equal rights and public contestation, is toleration of political dissent. Another element is allegiance to the republican political process itself (something that is crucially absent in an anocratic regime). Where these ideals are well established, disputes among citizens are settled not by lawless coercion, but by negotiation and mutual accommodation in the name of the common good. 

People are conservative about such things. Experiments in social psychology show us, and common sense tells us, that we cling to our ways of thinking. We repeat accustomed practices in new situations, unless emphatic experience convinces us that we must change. This fact suggests a key hypothesis: leaders will tend to act toward their foreign counterparts in the way they are accustomed to act toward rival domestic political leaders. 

In particular, leaders of well-established republics are expert in applying the methods preferred in a republican political culture; such leaders deal with their equals at home through negotiation and compromise rather than coercion. We would expect them to try the same methods abroad. The thesis sounds simple, yet it is grounded in facts of social psychology. 

This thesis seems to contradict to a widely respected way of approaching international relations--the school of "realpolitik" (more recently, "neorealism"). According to this long-established view, leaders make up their minds about something like war through rational calculations of what will most augment their nation's strength, taking into account the potential costs and gains of attacking or of making a concession and other pragmatic factors. Undoubtedly such calculations do have much to do with war and peace. 

There is a straightforward way to reconcile this viewpoint with ideas about political culture. One only needs to accept, as many of the great realpolitik theorists have acknowledged, that the actions of leaders are partly constrained by their political culture. Some painstaking statistical studies (reviewed in chapter 5) have indeed found that, on average, democratic leaders tend to act abroad in a somewhat more accommodating fashion than authoritarian ones. 

That is not necessarily a matter of involuntary habit alone. Leaders can rationally choose to maintain a reputation for dealing in a consistent way, whether vengeful or cooperative. The tendency of such leaders to negotiate or to apply force then becomes an objective factor, providing vital information which rival leaders should consider in any calculation. In a confused crisis this approach may be more reliable and efficient than for each side to guess how the other will make realpolitik calculations. The cost of holding true to one's ideals is thus repaid by the benefits of credible communication. When republican ideals are steadily maintained on both sides, the result can be something of the greatest value--mutual trust, where each side counts on the other to negotiate a solution without violence. 

This argument so far has a gaping hole. The observed inclination of republican leaders toward accommodation is only a crude statistical tendency. Republics have violated it time after time, launching atrocious aggression against other regimes ranging from tribal peoples to dictatorships. Still more disconcerting, democracies have regularly warred with oligarchic elites, although the leaders on both sides were used to peaceful ways at home. Why didn't republican political culture hold them back? Some factor is missing from the explanation. 

To find this missing factor, in chapter 6 I take a closer look at the instructive history of Switzerland, plus a few parallel cases. These show that the republican practice of accommodation applies only where the leaders of a state regard their foreign rivals as people who merit equal treatment, in roughly the same sense as domestic fellow citizens. In particular, oligarchic elites deny that democratic commoners are worthy of political equality, and readily put them down by force at home and abroad. 

We meet here the universal human tendency to divide people into "ingroup" and "outgroups"--a tendency that anthropologists and sociologists have long identified as central to war-making. People normally use one set of attitudes and norms for behavior with their ingroup, and a different set, often far more suspicious and belligerent, with outgroups. That makes it crucial to understand just where the political culture of people in republics instructs them to draw the dividing line. Our main task is to locate these boundaries, to check how they compare with the boundaries between various other types of regimes, and to see how those compare with the actual frontiers that men will do battle across. 

Watching ingroups gives us a sharp tool for dividing regimes into categories. The citizen elite of an oligarchic republic sees the bulk of its population as outgroup, a rabble which must be forced into submission. Democratic nations hold that coercion is legitimate against a much smaller category of their populations--chiefly those who are unwilling to abide by the law, namely "criminals." They may also view foreigners who reject democratic principles (despots or oligarchs who suppress commoners, for example) as virtual criminals, outside the group of "people like us." 

This suggests a deep connection between domestic suppression and wars among republics. The two types of coercion almost converge in civil wars. In chapter 7 I take these up, notably that troubling possible counterexample, the American Civil War. It turns out to fit into a larger category of warfare between republics which inhabit the border zone between oligarchies and democracies. On one side of such wars we always find a leadership that lived in dread of rebellion by an internal "enemy," a group or class whose liberty would pose a genuine threat to the authority of the elite--slaves, for example. The other side, distinctly more democratic, had no such problem. We shall find that republics can reliably be separated into two categories in a manner that is consistent with their pattern of mutual peace by stipulating that the suppression of a crucial domestic "enemy" political group as a body distinguishes oligarchies from democracies. Throughout history, I find, each category of regime readily warred with the other kind but not its own. 

Am I not making a circular argument, arbitrarily calling a regime an oligarchy, for example, only because it has gotten into a war with a democracy? Not at all: I have used the pattern of wars as a tool to discover reliable criteria for dividing regimes into consistent categories. We could call them Xs and Ys, but we may as well call them oligarchies and democracies, the terms generally used by people at the time. If a new regime arises, the criteria will allow us to place it in a category and predict with whom it will keep peace. 

The threat of domestic rebellion suggests why the character of a republican regime changes somewhere between having roughly one-third and two-thirds of men voting. The key is not in the exact numbers but in the emphasis given to holding down a domestic group. Oligarchic leaders, living in fear of the "rabble" at home, have readily battled the same sort of people abroad. Democratic leaders have often been equally belligerent with elites that stamped upon common people. Indeed, we will find that the detailed histories of the cases show that the suppression of a domestic group was usually one of the central issues in the crisis that led to war. 

Some may find it improbable that criteria based on simple political characteristics could be crucial in a world where so much strife seems to revolve blindly around religious, ethnic, or territorial distinctions. In fact, social psychology experiments and historical and ethnographic surveys have demonstrated that group boundaries are typically set in ways connected with political circumstances. In particular, democrats (or oligarchs) normally define even foreign democrats (or oligarchs) as ingroup, "people like us," at least in terms of what kind of political relations they expect. This manner of defining groups in terms of shared political beliefs and practices is probably an integral part of the political culture of republics. 

The border between oligarchy and democracy is only one of the zones of ambiguity. We also need specific criteria to distinguish republics from ambiguous autocracies and other authoritarian regimes. A survey of borderline cases in chapter 8 finds that a definite republic would go to war with a regime whose leader commanded powers like those held by, for example, the Prince Regent of England in 1812 or Kaiser Wilhelm II of Germany in 1914. To be precise, the rulers in question held an uncontested veto over military and foreign policy decisions, and the regime forcibly suppressed domestic dissent that threatened to remove that power. This category of regime may reasonably be called, if not pure autocracy, certainly authoritarian rather than republican. 

We are left with only a few other ambiguous cases of wars between regimes that might be called republics of the same kind. In chapter 9 I look these over, and find that historically a republic could war even with a regime that had recently held approximately free elections, provided the government was controlled by a leader or a small junta acting in a despotic manner. While constitutional mechanisms might function on the surface, the manifest political beliefs and domestic practices of the leadership rested on domination by force. Such regimes are easy to identify: the ruling clique executes other leading citizens to suppress their political activity, or throws some into jail and drives others into exile. We can lump these regimes with autocracies in the overall category of authoritarian regimes. 

Thus everything falls into place provided we understand that a "well-established" republic is a regime that not only has formal republican institutions to allow for public contestation among equals, but also a political culture among the leadership such that governance actually uses and relies upon those institutions. In short, we can only call a regime a well-established republic if the leaders customarily tolerate full public contestation among citizens. We can set authoritarian regimes of every kind apart from republics simply by looking to see whether demands for loyalty are so concentrated on a leader, family, or clique that anyone, even in the citizen class, who works to have the leadership replaced is risking severe punishment. 

There still remain a few cases where it is hard to be sure whether or not toleration of dissent was a reliable practice at the time of an international crisis. In chapter 10 I review these cases and find that the problem is usually that the regime was only recently created. It is reasonable not to call any republic "well-established" until it has existed long enough to demonstrate a stable, tolerant character. If required to be specific I would include as many regimes as possible in this category, while preserving the rule of peace among well-established republics of the same kind. When toleration of dissent has persisted for three years, but not until then, we can call a new republic "well established." For there have been no wars between democracies more than three years old (aside from a few doubtful ancient Greek cases), and wars between such oligarchic republics have been exceedingly rare (only two or three ambiguous cases exist). 

The way this category must be circumscribed is instructive, for proto-republics less than three years old do fight wars with republics. Whatever normally inhibits confrontations between republics is evidently weak when a republic is born, but rapidly becomes stronger. Just what is this thing that was not "established"? The republican constitutional structures, the elections and legislatures, were often operating well before the war broke out. That is further evidence against the proposition that constitutional features necessarily make for peace. They are only a precondition. Another and decisive factor is something set in place more gradually--but not the sort of social, economic, or cultural change that takes decades to develop. 

The most likely candidate for this factor is the political culture of the leadership. If there is to be a stable republican government, the new leaders must rapidly learn to make compromises, or give way to people who will. This has the right time scale of a few years: partly through changes in personnel, partly through personal changes, new beliefs and practices for managing conflicts take hold. 

One important qualification remains. People may see enemies where the historian is not so sure. There have been cases where regimes attracted more hostility from a republic than seems appropriate in hindsight. In all such conflicts I find that the leaders on one side believed, not without evidence, that the other side refused to behave in the ideal republican fashion, preferring subterfuge and violence to honest compromise. The way historians classify a regime evidently matters less than what each side believed at the time. That reinforces the proposition that the perception of a shared political culture is essential for maintaining peace among republics. Fortunately, misperception has encouraged conflict only in a few cases of especially young and ambiguous regimes. 

The consistent pattern of oligarchic/democratic war and peace, the type of criteria that make the crucial distinctions, and the few exceptions for newborn and misperceived regimes all suggest that the key is the political culture of the leadership. But it is not enough to explain something in abstract terms; we must check whether the explanation fits the details of specific cases. If we look at the actions of leaders in a given crisis, does their diplomatic style reflect their regime's domestic political culture? If so, does the style affect the outcome of the crisis? In chapter 11 I review the few relevant social science studies, which agree that on average these effects are real. But that is only suggestive, and such things are difficult to measure. I approach the problem through the investigation of individual cases. This method does not line up features of cases alongside one another, as in the method of comparative case study, but tries to understand directly the mechanisms at work. My approach is to ask a counterfactual question: "If that regime had conformed to a different political culture, would its leaders have negotiated differently, in such a way as to change the chances for war?" 

Such a question can be answered wrongly for a given crisis, but if one finds a plain connection running from the political culture to the negotiating style to the outcome, and finds such a connection in crisis after crisis, then it becomes plausible that political culture provides the explanation for democratic peace. That takes us far enough for practical purposes--in the end the best we can hope for is to find an explanation plausible enough to suggest which factors people should take into account in the real world. 

Such anecdotal evidence, displaying political culture as a major diplomatic factor, is presented in cases throughout the book, but I focus on the question in chapters 11 through 13. First I give some examples of diplomacy between republics and autocracies and between autocracies. I picked cases that would provide the toughest test, drawing from my list of borderline cases plus some additional cases that have been exceptionally well documented by historians. 

The results can only be impressionistic, but the impression is very clear. In negotiations each regime did tend to behave according to its political culture. Time and again we observe authoritarian leaders undeniably extending their domestic style of behavior abroad by using coercion rather than seeking mutual accommodation, in ways that made war more likely. Republican behavior was plainly different--so much so that in quite a few cases the difference created an "appeasement trap." The republic tried to accommodate a tyrant as if he were a fellow republican; the tyrant concluded that he could safely make an aggressive response; eventually the republic replied furiously with war. The frequency of such errors on both sides is evidence that negotiating styles are not based strictly on sound reasoning. 

Republics can turn willfully bellicose. In chapter 12 I offer examples of republican leaders acting belligerently and even abusively from the very outset. In every case, however, this behavior was incontestably connected with their conviction that the rival regime was far from republican, and hence fit to be coerced. Some examples of negotiation among undoubted democracies leave a contrasting impression, obvious and consistent, of a less belligerent style of diplomacy. 

There remain a few troubling confrontations--not wars but serious nonetheless--in which democracies acted belligerently toward other democracies. In chapter 13 the problem is identified as a conflict between ways of defining the ingroup. Leaders may decline to see others as "people like us" simply because they are dark-skinned, for example, or Catholic, or born on foreign soil. Such prejudiced identifications may displace the principle of republican ingroup solidarity. The danger is greatest in imperialist situations where local affairs are put in the hands of a hierarchical subculture such as the military. Fortunately, none of this has brought war except where one regime was so poorly established that there were excellent grounds for doubting that its leaders should be considered republicans, 

If well-established republics do not fight their own kind, just what sort of diplomatic relationships do they form with one another? Chapter 14 surveys comprehensively a record of republican confederation--hitherto overlooked so far as I know--which reaches back to the ancient Greeks. A remarkably large number of cases can be summarized in a final generalization, new and important: Republics and only republics have tended to form durable, peaceful leagues. Wherever in history several republics were found, they surrendered some degree of sovereignty to international councils of representatives who negotiated and voted as equals. The spectacular record of republican confederation is further evidence of a powerful tendency for political culture to extend from domestic into foreign affairs, among those who perceive each other as equals. Republican leaders establish the same kinds of mechanisms for peaceful decision-making internationally that they are familiar with domestically. This confounds realpolitik theory, which sees alliances and other forms of maintaining peace as simply a matter of balancing material forces against some external threat (as NATO countered the Soviet Union). That cannot explain why alliances among authoritarian regimes are far less stable. 

It would be easy to conclude that we may find security from war by striving to create more democracies. The idea is an old one, yet even historians seldom recognize how often democracies have thrown themselves into just such efforts, from ancient Greece to our own day. In chapter 15 I give a historical survey--again, to my knowledge the only comprehensive one to date--of the results of such democratic crusades. The policy has often been successful, but more often it was applied with too heavy a hand and failed. Any attempt to impose democratic regimes by force can also undermine a more immediate goal: fostering an international "republican" political culture of peaceful negotiation. 

This has been only a sketch of my argument, and much will become clear only as we look over borderline cases. It is there above all that we will turn up all the clues we need to solve the puzzle. The puzzle, that is, of exactly how well-established democracies like the Swiss Forest States could maintain centuries of peace, and precisely where there are defects in democracies that make the streets of their cities shudder with explosions. 

--From Never at War: Why Democracies Will Not Fight One Another, by Spencer R. Weart. (New Haven, CT: Yale University Press, 1997) © 1997 by Spencer R. Weart and Yale University Press, used by permission.

You are the visitor since 11/25/02