In the Western intellectual tradition, systematic thinking about the ethics of war goes back to ancient Greece. The body of thinking that developed in that tradition over the centuries is referred to as the just war tradition. Efforts to organize the insights of the just war tradition into a single coherent understanding of the ethics of war are instances of just war theory. To introduce our discussion of just war theory in the remainder of this book, this chapter offers a brief history of the just war tradition, of the ideas that developed in this tradition. The characteristic feature of both the just war tradition and just war theory is an effort to limit war, both in its frequency and in the savagery with which it is fought.

Vitoria and the Spanish war against Native Americans

Following the European discovery of America by Columbus, various states in Europe waged war against and exploited the native populations of the New World. Consider the Spanish aggression in Latin America. In 1493, the year after his initial voyage, Columbus, sailing again for Spain, returned to the Caribbean and began a conquest of the Taino people of that region. In 1519–1521, the Spanish, under Hernán Cortés, conquered the Aztec civilization in present-day Mexico. In 1532–1533, the Spanish, under Francisco Pizzaro, conquered the Inca civilization in present-day Peru. These wars of conquest were fought primarily for the precious metals to be had. Many of the surviving natives were put under systems of forced labor. An empire was established, which “in extent and population, and cultural diversity … exceeded even [that of] ancient Roman, previously the standard of imperial power.”