How does a governing coalition’s size affect the extent and type of violence in society? The model developed here predicts that larger coalitions are less likely to fight for private goods (e.g., plunder) than for public goods (e.g., defense), yet this substitution need not reduce the overall scale of fighting. That prediction is tested by investigating how Rome’s transition from Republic to Empire affected military patterns. The raw data and three empirical tests suggest that the Republic engaged in more battles overall and that Republican battles had more of a public goods component. This study furthers our empirical knowledge about the ancient world while bringing data to bear on contemporary debates about the causes of peace and war.

执政联盟的规模如何影响社会暴力的程度和类型？这里开发的模型预测，较大的联盟为私人物品（例如掠夺）而战比为公共物品（例如防御）而战的可能性较小，但是这种替代并不需要减少总的战斗规模。通过研究罗马从共和国到帝国的过渡如何影响军事模式，检验了这一预测。原始数据和三个实证检验表明，共和国总体上参与了更多的战斗，而共和党的战斗更多地涉及公共物品。这项研究进一步丰富了我们对古代世界的经验知识，同时将数据用于有关和平与战争原因的当代辩论。