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70 Years of Peace: By Accident or Design?

Enduring Peace


One of the irritating things about being an empirical researcher is having to change your thinking when new data comes in. A new report released by One Earth Future’s think tank, OEF Research, is forcing me to reconsider some important arguments we have made in the past.

The second half of the twentieth century showed marked declines in both the number of major wars and the deaths associated with them. Conflict scientists, including OEF Research, have argued that these declines are the result of a number of global trends including improvements in human development, more economic integration, and better systems for peace intervention. In 2015, statistician Nassim Taleb and his colleague Pasquale Cirillo raised the possibility that this decline may not be as meaningful as researchers thought. While the decline is real—it is true that the rate of wars declined in the twentieth and early twenty-first centuries—it is possible that this is an accident of statistics rather than a result of genuine changes in the international system. Wars are rare, and big wars are rarer. That means it’s possible the world could simply have gotten lucky in the twentieth century. The Taleb critique was a concerning possibility, but there were some problems with it: the data they used to generate their argument were messy, and they refused to share them with other scholars to allow independent replication of their results. Their critique also dismissed the proposed scientific explanations for the decline and the evidence that supported those explanations. The research on conflict is not a purely statistical debate, and researchers who argue that the world is getting more peaceful because of economic engagement or diplomacy usually have good reasons behind that argument aside from the statistical linkages they find between their variables and peace. Still, the possibility that the decline in deaths may be an artifact of statistics raised a worrying possibility.

Following the debate triggered by Taleb’s work, OEF Research re-examined this question with Aaron Clauset, a computer scientist and internationally recognized expert in the statistics of complex systems. Clauset analyzed the Correlates of War dataset using state-of-the-art statistical modeling of complex systems to examine whether the data are more consistent with a random risk of major war or whether there is evidence that the decline is related to some external causes. In the resulting report released by OEF Research, he concludes that the Correlates of War data show the pattern of major wars is consistent with a “stationary conflict-generating process.” In other words, there is not yet enough statistical evidence to conclude that the risk of having a huge interstate war has actually declined, and it’s possible that the peace we’ve seen is the result of short-term trends or is even purely random.

What Would a Modern War Look Like?

The implications of this are fairly chilling for both policy and research. Nobody really knows what a modern war would look like: in the years since the end of WW2 there have been enormous changes in the technology and lethality of weapons but also enormous increases in their precision and the ability to limit collateral damage. If a major war breaks out between world powers, the results will be unpredictable, but likely will be devastating to the nations involved and probably the rest of the world. In research terms, this analysis is a worrying reminder that empirical science is a process of constantly testing and refining our claims, and this analysis poses a fairly foundational challenge to a large body of empirical work on the decline in war. It calls for a consideration of multiple different statistical methods, and a consideration of the possibility that the structure of conflict data makes it difficult to identify conclusive trends, even if they do exist.

There are reasons to be optimistic, however. Like Taleb’s critique, this is at its heart a statistical argument, not a theoretical one. Clauset’s analysis is purely about the structure of the data and whether the data show any measurable distortion away from underlying trends. The rareness of wars means that the data are fairly variable, and it’s possible that global trends in human and economic development and good governance have driven a decline that is not yet noticeable in the data only because we don’t have enough data to clearly demonstrate it. The arguments in support of peace are well-developed and linked to clear chains of logic and theory that support the existence of a decline. There are also nuances to his argument; Clauset finds that the period following WW2 had more moderate-sized but fewer small and major wars than would otherwise be predicted, suggesting that global systems or pressures did impact the patterns of conflict in some way. Like any single study, this research cannot be taken as the sole answer to the question of whether war is becoming rarer, and it is weighed against a body of theory and research that provides reasons to think otherwise.

Can the Peaceful Trends Continue?

Clauset’s analysis suggests that if the peaceful trends continue, we will be able to say with certainty that the risk of war has declined once we have enough data to make that claim—sometime in the middle of the twenty-second century. Until then, to me this leads to two main conclusions. The first is a reminder that researchers must be humble in our claims and prepared to change our beliefs as additional data become available. While I still fall on the side of believing that the weight of theory and research suggests that the world is doing a better job of maintaining peace than we did in the past, this research suggests to me that this conclusion is more debatable than I previously thought. The second conclusion is that specifically because this research calls into question the existing claims about the trends in peace, the research and policy work being done on the prevention of violence is more important than ever. If the risk of major war remains just as high today as it was at the outbreak of WW I, then the work being done by United Nations agencies, foreign ministries, the development community, and others on the prevention and containment of political violence is not just important for the prevention of small conflicts. It may be the main thing standing between the world and another world-changing war.