The post–World War II period has shown a clear, albeit erratic, decline of organized violence. While the word “peace” has many interpretations, some of them wide enough to incorporate “all good things,”Footnote 1 the reduction of armed violence must be at its core. Violence in this period peaked during the Chinese Civil War, the Korean War, the Vietnam War, and most recently the Syrian Civil War, but the peaks are declining over time and the long-term trend is clearly downward. Some 470,000 people—combatants as well as civilians—were killed in battle-related violence in interstate or civil war in an average year in the first five-year period after the end of World War II. The number was down to around 80,000 in the most recent five-year period studied (2014–2018). In relative terms, as a share of world population, the decline is even more striking. Based on the tripling of the global population since 1950, the probability of being killed in interstate or civil war has declined by a factor of seventeen from the first years after WWII to the present.Footnote 2 Over the past sixty years, the risk of being killed as a result of one-sided violence (violence by states or organized groups against unorganized civilians) has also declined markedly. The same goes for criminal violence and capital punishment. If we look further back, the decline in violence is even more striking. Annual death rates of 0.5 percent per year as a result of organized violence were not uncommon in stateless societies in the past. The most violent countries today fall well below such levels, even if we include deaths from violent crime.Footnote 3 We are far from achieving world peace, as evidenced by the protracted civil war in Afghanistan, the numerous violent conflicts in the Middle East, and periodic belligerent threats of fire and fury from regional and global powers. But we may at least be hopeful that the world is moving in the right direction. How did we get this far, and where do we move next?
The Democratic Peace
“There is no machine that can deliver peace. No equation to unravel. No hidden secret to uncover,” writes Alex Bellamy in his new book World Peace (And How We Can Achieve It).Footnote 4 Yet, democratic peace theory claims to provide such a formula. Democracy itself is a form of organized conflict resolution. Peaceful norms generally govern the internal affairs of democratic countries and these norms appear to extend to mutual relations between democracies. Historical data show that two democratic countries rarely, if ever, go to war against each other. Wars are fought between authoritarian countries and, even more often, between democracies and autocracies. When states with different types of regimes end up at war, it is rarely a democracy that initiates the violence. The bloodiest interstate wars in the twentieth century (including the two world wars, the Korean War, and the Iran-Iraq War) were all initiated by autocracies. Highly democratic countries also rarely, if ever, fight civil wars over competing claims to government. And secessionist struggles within democracies are usually inherited from a colonial past (as in Northern Ireland) or an authoritarian past (as in the Basque conflict) and are mostly conducted with low levels of violence. One-sided violence by states or other organized parties against unorganized civilians—including genocide and politicide—is generally committed by and in authoritarian and, in particular, totalitarian states. The most glaring example of such violence in the post–World War II era is the Great Leap Forward in Maoist China, which took place from 1958 to 1962 and left around forty-five million dead.Footnote 5 Low-level communal violence between ethnic groups is rarely found in stable democracies, and even violent crime is generally less deadly in such countries than in their more autocratic counterparts. Democracies are also generally better at managing their resources in a manner that avoids preventable deaths. For example, as Amartya Sen has noted, large-scale famine does not occur in democracies.Footnote 6 India today still experiences extensive hunger and extreme poverty, but since its independence and transition to democracy there has been no catastrophe coming anywhere near the Bengal famine of 1943, which left an estimated two to three million people dead.
Challenges to the Democratic Peace
Although the empirical evidence for the democratic peace is compelling, it has serious limitations as a prescription for world peace. Let us assume, somewhat optimistically, that around half of the world's countries can be considered democratic. Then, if we follow democratic peace theory, interstate war would only be ruled out in one-quarter of any given pair of nations. The vast majority of wars occur between neighboring countries, so most pairs of states—such as Bolivia and Chad—are unlikely candidates for war in any case, regardless of regime type. Furthermore, democracies tend to cluster geographically, often forming “security communities” (Europe, for example), and therefore the risk of interstate war will be very low in these regions and much higher elsewhere.
Scholars from a variety of theoretical perspectives have questioned the causal mechanisms of the democratic peace, some of them drawing on other liberal perspectives on international affairs. Proponents of the “quality of government peace” highlight the value of a benign government with low corruption in maintaining peace even in the absence of electoral democracy.Footnote 7 Proponents of the “capitalist peace” point to the lack of democracy in command economies. To them, the emergence of a market economy accounts for democracy as well as peace.Footnote 8 This perspective is closely linked to the idea that economic integration provides a powerful incentive to avoid violent conflict, an important ingredient in Bruce Russett and John Oneal's notion of a “liberal peace.”Footnote 9 Others have focused on economic development, which makes war less attractive. An influential World Bank report argued that low levels of economic development provide many individuals with an economic incentive to join violent insurgencies.Footnote 10 Some have argued for a “territorial peace,” whereby it is the absence of active territorial disputes and the existence of a stable border that is the best predictor of peace between two countries—not whether they are both democracies.Footnote 11 Based on findings that gender equality in politics reduces violence within as well as between societies, some have argued for a “feminine peace” as the core of the democratic peace.Footnote 12 Finally, a recent study argues for a “civil society peace.”Footnote 13
A great deal of effort has been invested in studying whether one or more of these factors can better provide the explanatory power behind what is most commonly observed and referred to as the “democratic peace.” Many studies conclude that though they cannot provide such an explanation, certain aspects of democracy may play a more important role than others. Håvard Hegre and his colleagues, for instance, find that in democratic dyads, social accountability—that is, civil society holding government and politicians to account for their actions—is a stronger predictor of non-belligerence than electoral accountability or horizontal accountability (to other national institutions and branches of government), but not to the exclusion of the other two dimensions.Footnote 14 Most studies also argue that other factors can make independent contributions to peace, even in the absence of democracy. The “East Asian peace”—the absence of interstate war in East Asia since 1979—for instance, has been considered a key factor in the global decline of armed conflict in recent decades. This peace is arguably due more to economic development and economic integration than to democracy, although several states in the region have moved in the direction of greater democracy during the same period.Footnote 15
Separating the effects of the different factors is difficult because they are so closely related to each other, with one influencing the next, and vice versa. If, for instance, a market economy is important for the emergence of democracy, we may interpret democracy as a key mechanism for translating the market economy into peace. And, with regard to the “feminine peace,” it is hard to see how gender equality can emerge except as part of a broader set of democratic institutions.
The Realist Challenge
Realists have always presented a different and serious challenge to any explanation of peace based on democratic norms. Peace, they insist, requires a certain amount of force. On this view, the state provides internal peace by establishing an authority with a monopoly on violence. Rather than succumbing to violent fights between competing warlords or ethnic groups, society is regulated by a set of institutions that provide a measure of order and that intervene, forcefully if necessary, against those who disturb it. Although the power of a strong central government can be misused for repression and violence, the emergence of competent states generally reduces violence within nations and increases the chances of compromise between nations to resolve conflicts.
At the interstate level, we lack a similar monopoly on violence and realists see the international community of nations as anarchic, much like a failed state at the national level. International peace, then, depends on the distribution of power in the international system, including patterns of alliance building. Power is the key variable, although realists differ on the issue of whether a balance of power or power preponderance provides the most stable outcome.Footnote 16
This challenge is formidable, but it has blind spots. For one, this perspective ignores the growth of international law and the phenomenal proliferation of both public and private international institutions, particularly in the period after World War II. The growing web of shared organizational memberships increasingly ties countries together with a set of mutual obligations that work to their advantage in the long run. In particular, the United Nations and its specialized agencies exercise considerable influence in international affairs, not just in political terms but over a wide spectrum of functional cooperation in health, education, transportation, and so forth. Similarly, the Bretton Woods institutions (the World Bank and the International Monetary Fund) play a leading role in the international coordination of economic affairs, along with regional institutions such as the Association of Southeast Asian Nations (ASEAN). In parallel, international law is generated formally through treaties and also informally through everyday practice. In this way, international law and international organizations provide a third pillar of what its proponents term the liberal peace.Footnote 17
Realists object that the United Nations has limited power to intervene in armed conflict because doing so would require full agreement among the major powers, which may be impossible to achieve without the consent of the antagonists. However, international society is not without tools that have coercive elements, which contribute to keeping the peace.Footnote 18 The post–World War II era has seen the massive expansion of international peacekeeping, both in terms of the number of missions and the number of personnel involved. From a modest start with a handful of observers in the Middle East in 1948, the fourteen current UN worldwide peacekeeping operations command some 110,000 personnel. Additional peacekeeping is provided by operations conducted by regional organizations, such as the African Union. These operations have a clear effect in limiting violence: one study finds that the deployment of 10,000 peacekeepers reduces battlefield violence by over 70 percent.Footnote 19 The mandates for peacekeeping missions have also moved toward a greater role for peace enforcement—that is, enforcing peace against the will of the parties to the conflict. Here, the boundaries between cooperation and coercion can easily become blurry. Moreover, missions that aspire to peacekeeping can also be exploited for selfish reasons by major powers, as was the case with the NATO-led intervention in Libya in 2011. The collaborative and peace-promoting pattern of peacekeeping is best secured when it is founded in international law and approved by the United Nations Security Council or a similar representative regional body for conflicts where the major powers do not have a direct stake in the outcome.
Clearly, peacekeeping and, even more so, peace enforcement are most promising for smaller conflicts and particularly for conflicts where the major powers do not have a direct stake in the outcome and are likely to exercise a veto in the Security Council. Conflicts such as the Korean War and the Vietnam War, and more recently the civil war in Syria, have escalated beyond recognition because of the involvement of major powers. At their peak, these wars each accounted for a large fraction of global violence. Peacekeeping is unlikely to be applied to prevent such conflicts from escalating.
Even in the absence of agreement between the major powers to allow interventions authorized by the Security Council, there has been a large increase in peace agreements in ongoing conflicts, often facilitated by the mediation efforts of states and nongovernmental organizations.
An Unjust Peace?
While the world has become more democratic and more peaceful, has more competent states, and is becoming ever more economically and politically collaborative, many scholars and policymakers worry about the effects of the rising global inequality that has accompanied these changes. Is the relative peace of the current period a temporary phenomenon, distracting from the extreme inequity that is breeding dissatisfaction and that will eventually explode into violence? In many industrialized countries, following a long period of decline, inequality has been rising since the early 1990s. Interpersonal inequality at the global level has decreased markedly, mainly because of the large-scale reduction in extreme poverty in the world's two most populous counties, China and India.Footnote 20 But at the same time, interpersonal inequality within each nation is on the increase. Could this lead to internal unrest and even civil war?
There is little evidence for a strong direct relationship between interpersonal economic inequality and violent conflict as measured by, for instance, the Gini index. However, inequality between ethnic or national groups (particularly when coupled with political exclusion) are factors significantly associated with civil war.Footnote 21 The good news is that while economic inequality has been increasing in many countries, group inequality and discrimination are, if anything, declining. A competent state plays an important role in alleviating the potential negative effects of globalization and the market economy and in preventing discrimination, just as the capitalist peace will not be peaceful in the long run if the market economy is left to itself with no regulation.
A Social-Democratic Peace
Let us consider some of the above elements that can contribute to a more peaceful world: democracy, a market economy, a competent state, international economic and political cooperation, and policies for reducing discrimination and inequalities along ethnic and national lines. This looks very much like social democracy. Of course, if we require that all of these things be present at the same time, we limit the likely zone of peace even more stringently than the democratic peace itself. On the other hand, if we assume that all of these factors have some influence on peace, we not only have a formula for peace but also a political program for the continued expansion of the zone of peace. As a leading social-democratic politician in Norway, the late Einar Førde, sloganized in a book title almost forty years ago, “We are all social democrats.”Footnote 22 Had Førde lived to see the rise of Donald Trump and right-wing populism in Europe and the decline of traditional social-democratic parties in Europe, he might have been more cautious. But the point still stands: The values associated with social democracy have, to a large extent, been embraced by competing parties. Most socialists accept an important role for the market economy, and conservatives go along with high taxation and an active public sector. Even populists embrace the welfare state and often try to adopt social-democratic values to defend their positions, as when opposition to immigration is justified with the sustainability of the welfare state. While, in recent elections, voters in Europe have defected from social-democratic candidates, public opinion polls show that they have maintained (or even increased) their allegiance to a fair distribution of resources and an active role for the government in education and healthcare.Footnote 23 And right-wing authoritarianism is not rising unchecked. In the U.S. presidential election of 2016, after all, a majority of Americans voted for Hillary Clinton to succeed Barack Obama. Autocrats are under siege in Hong Kong, Turkey, and Russia. International trade remains high even under current trade wars.
To reiterate, the world is still a violent place, but substantially less so than it was during World War II, the Great Leap Forward in China, or the Vietnam War. International wars on such a scale, or even larger, are low-probability events, but not so improbable that they can be discounted. Lewis Fry Richardson, the British physicist who first discovered that the size of interstate wars over time follows a power-law distribution, said in a discussion of his work on arms races that his equations “describe only what happens if men do not stop to think.”Footnote 24 Today, we have the opportunity to see clearly the dire consequences of a future cataclysm and nurture the hope that humankind will collectively be able to avert it.
In this essay, I have generally interpreted “peace” to mean the reduction of organized physical violence. Many critics argue that this is too limited and that the word peace must entail a broader interpretation. This is a fair perspective, but given the history of organized human violence, I do not at all see reduction of physical violence as a limited program. Numerous proposals have been put forward to add a “positive peace” dimension to the “negative” aim of reduced violence. The social-democratic peace in many ways looks like some of these positive peace notions. As Bellamy notes, the Global Peace Index, by including low levels of corruption, a sound business environment, good relations with neighbors, the free flow of information, a well-functioning government, and the equitable distribution of resources, defines peace as “those things most valued by social democratic societies.”Footnote 25 Similarly, goal sixteen of the UN's Sustainable Development Goals calls upon states to “promote peaceful and inclusive societies for sustainable development, provide access to justice for all and build effective, accountable and inclusive institutions at all levels.”Footnote 26 I have put forward social-democratic peace as a formula for reducing violence rather than as another extended notion of peace. Nevertheless, it is hardly a weakness if a proposed program for moving closer to world peace coincides with common definitions of a widespread extended concept of peace. In other words, the medicine tastes sweet while also curing the disease.
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