Abstract
Previous analyses of civil war trends tend to be informal and consider only post 1945 data. We examine data on civil wars over the period 1816–2005, using new methods for evolutionary growth processes. We find a number of new patterns and trends in civil war that have received little attention in previous research, including a structural break in frequency of conflict with decolonialization, as well as evidence of periodicity in civil conflict. We develop new measures of civil war intensity and impact, and find that conflicts have been generally more severe in the 20th than in the 19th century. We also find that the frequency-severity distribution of civil war does not appear to follow a power-law distribution, unlike data on many other types of conflict. Although structural trends suggest an increase in future civil wars, we discuss possible limiting factors that might prevent this in light of the recent observed decline in civil wars after the Cold War.
Acknowledgments
L.C.M. Miranda and L.F. Perondi acknowledge the Brazilian National Research Council for the partial support of their work. K.S. Gleditsch would like to acknowledge support from the Research Council of Norway (180441/V10). We are grateful for comments and helpful discussions with Vincenzo Bove, Raul Caruso, Belén González, Nils Metternich, Cliff Morgan, Andrea Ruggeri, and Anja Shortland.
Appendix: Probability density as a function of the severity indicators
The civil wars distribution as a function of the severity indicators were constructed as by counting, for each value of the corresponding indicator, the number of conflicts. Since the values of both indicators vary typically four orders of magnitude, our distributions were assembled using a logarithmic binning for both indicators. In the Table below we present a summary of the data used in this study. Table 6 shows, for instance, that beginning with 1 conflict ln (Intensity)=–1.7±0.1 we ended up with 1 war having log (Intensity)=8.4±0.1 (i.e. between roughly 6310 and 10,000 battle deaths per day).
| ln (Intensity) | Intensity probability density function | ln (Impact) | Impact probability density function, a |
|---|---|---|---|
| –1.7±0.1 | 0.023 | –3.7±0.1 | 0.017 |
| –1.4±0.1 | 0.023 | –1.7±0.1 | 0.017 |
| –1.1±0.1 | 0.023 | –1.5±0.1 | 0.034 |
| –0.8±0.1 | 0.023 | –1.3±0.1 | 0.017 |
| –0.4±0.1 | 0.070 | –1.1±0.1 | 0.034 |
| 0±0.1 | 0.023 | –0.9±0.1 | 0.017 |
| 0.2±0.1 | 0.023 | –0.7±0.1 | 0.017 |
| 0.4±0.1 | 0.164 | –0.5±0.1 | 0.034 |
| 0.6±0.1 | 0.047 | –0.3±0.1 | 0.017 |
| 0.8±0.1 | 0.023 | 0±0.1 | 0.017 |
| 1±0.1 | 0.210 | 0.2±0.1 | 0.069 |
| 1.2±0.1 | 0.210 | 0.4±0.1 | 0.034 |
| 1.4±0.1 | 0.280 | 0.6±0.1 | 0.034 |
| 1.6±0.1 | 0.374 | 0.8±0.1 | 0.155 |
| 1.8±0.1 | 0.210 | 1±0.1 | 0.223 |
| 2±0.1 | 0.164 | 1.2±0.1 | 0.069 |
| 2.2±0.1 | 0.164 | 1.4±0.1 | 0.086 |
| 2.4±0.1 | 0.234 | 1.6±0.1 | 0.155 |
| 2.6±0.1 | 0.257 | 1.8±0.1 | 0.137 |
| 2.8±0.1 | 0.187 | 2±0.1 | 0.155 |
| 3±0.1 | 0.164 | 2.2±0.1 | 0.120 |
| 3.2±0.1 | 0.164 | 2.4±0.1 | 0.137 |
| 3.4±0.1 | 0.257 | 2.6±0.1 | 0.155 |
| 3.6±0.1 | 0.140 | 2.8±0.1 | 0.103 |
| 3.8±0.1 | 0.164 | 3±0.1 | 0.241 |
| 4±0.1 | 0.187 | 3.2±0.1 | 0.155 |
| 4.2±0.1 | 0.117 | 3.4±0.1 | 0.189 |
| 4.4±0.1 | 0.093 | 3.6±0.1 | 0.223 |
| 4.6±0.1 | 0.093 | 3.8±0.1 | 0.344 |
| 4.8±0.1 | 0.140 | 4±0.1 | 0.206 |
| 5±0.1 | 0.117 | 4.2±0.1 | 0.120 |
| 5.2±0.1 | 0.047 | 4.4±0.1 | 0.189 |
| 5.4±0.1 | 0.070 | 4.6±0.1 | 0.137 |
| 5.6±0.1 | 0.093 | 4.8±0.1 | 0.086 |
| 5.8±0.1 | 0.047 | 5±0.1 | 0.137 |
| 6±0.1 | 0.023 | 5.2±0.1 | 0.155 |
| 6.2±0.1 | 0.023 | 5.4±0.1 | 0.103 |
| 6.4±0.1 | 0.047 | 5.6±0.1 | 0.034 |
| 6.6±0.1 | 0.093 | 5.8±0.1 | 0.069 |
| 7±0.1 | 0.047 | 6±0.1 | 0.017 |
| 7.2±0.1 | 0.023 | 6.2±0.1 | 0.052 |
| 7.6±0.1 | 0.070 | 6.4±0.1 | 0.120 |
| 7.8±0.1 | 0.023 | 6.6±0.1 | 0.086 |
| 8.4±0.1 | 0.023 | 6.8±0.1 | 0.034 |
| 7±0.1 | 0.069 | ||
| 7.2±0.1 | 0.086 | ||
| 7.4±0.1 | 0.069 | ||
| 7.6±0.1 | 0.034 | ||
| 7.8±0.1 | 0.052 | ||
| 8.2±0.1 | 0.034 | ||
| 8.6±0.1 | 0.052 | ||
| 8.8±0.1 | 0.017 | ||
| 9±0.1 | 0.034 |
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