Alarming increase in wars

New research by Professors Mark Harrison from the University of Warwick and Nikolaus Wolf from Humboldt University has revealed that between 1870 and 2001, the frequency of wars between states increased steadily by 2% a year on average. Between 1870 and 1913, the frequency of ‘pairwise’ conflicts (the numbers of pairs of countries involved in conflicts) increased on average by 6% per year. The frequency of wars increased by 17% per year in the period of the First and Second World Wars, and by 31% per year during the Cold War. In the 1990s, the frequency of wars between states rose by 36% per year.

Professor Mark Harrison explained how: ‘The number of conflicts has been rising on a stable trend. Because of two world wars, the pattern is obviously disturbed between 1914 and 1945 but remarkably, after 1945 the frequency of wars resumed its upward course on pretty much the same path as before 1913.’

The graph below illustrates this increase in pairwise conflicts. It only includes wars between states and does not include civil wars. Conflicts range from full-scale shooting wars and uses of military force to displays of force (sending warships and closing borders, for example). Although Harrison and Wolf’s study does not measure the intensity of violence, it reflects the readiness of governments to settle disputes by force.

According to Harrison and Wolf, this increase in the frequency of pairwise conflicts can be explained by two principal factors: economic growth and the proliferation of borders. The number of countries has thus almost quadrupled since 1870, rising from 47 countries in 1870 to 187 in 2001.

Harrison continued: ‘More pairs of countries have clashed because there have been more pairs. This is not reassuring: it shows that there is a close connection between wars and the creation of states and new borders.’

Looking specifically at the countries that have initiated disputes, the study shows that there is no tendency for richer countries (defined by a higher GDP per head) to make more frequent military interventions than others. The readiness to engage in war is spread relatively uniformly across the global income distribution.

Thinkers of the Enlightenment believed, and many political scientists still believe today, that the political leaders of richer and more democratic countries have fewer incentives to go to war. Over the course of the twentieth century, on the whole, countries have become richer, more democratic and more interdependent. Yet, Harrison and Wolf’s study disproves the theory that as GDP increases countries are less likely to engage in warfare.    

In Harrison’s view, political scientists have tended to focus too much on preferences for war (the ‘demand side’) and have ignored capabilities (the ‘supply side’). Although increased prosperity and democracy should have lessened the incentives for rulers to go to war, these same factors have also increased the capacity of countries to go to war. Economic growth has made destructive power cheaper. It is also easier for modern states to acquire destructive power because they able to tax more easily and borrow more money than ever before.

Mark Harrison concluded that: ‘The very things that should make politicians less likely to want war – productivity growth, democracy, and trading opportunities – have also made war cheaper. We have more wars, not because we want them, but because we can.’

The full paper is due to be published in The Economic History Review.