This is a careful and excellent study of book 2 of the first volume of Juan de Solórzano’s treatise De Indiarum Jure. An oidor (judge) in the Audiencia of Lima, Solórzano (1575-1654) served in the Councils of Castile and the Indies. He was therefore part of the Spanish administration when Spain’s hegemony was being challenged on both sides of the Atlantic, and when the Spaniards themselves were debating whether or not their nation was in decline. Sólórzano’s book, published in the first half of the seventeenth century and often quoted in Spain and abroad into the nineteenth century, is primarily a defense and a legitimation—through elaborate scholastic reasoning—of Spain’s right to America.

Besides providing an extensive summary of incisive commentary on Solórzano’s second book, James Muldoon leads the reader on a wide-ranging tour of the sources, and the methodological and cultural context, of De Indiarum Jure. Beginning, in the first chapter, with Innocent IV’s commentary on Quod Super His and the twelfth- and thirteenth-century canonical opinions on the nature of Christian and non-Christian relations, Muldoon goes on to quote Solórzano’s list of the ten titles advanced as justification for Spanish rule in the New World (p. 34). They range from the claim that God had granted the Americas to Spain to the concern about the savage nature of the natives. The last and, for Solórzano, the only valid argument was that the “pope could grant the lands of infidels to Christians” for the purpose of civilizing and Christianizing them.

Muldoon shows how Solórzano musters arguments for and against each of the titles and then proceeds to dismiss all of them except the appeal to papal authority. Along the way, Solórzano embraces the natives’ right to their own rule and emphasizes—in enlightened fashion—the universal unity of mankind. For him, the natives were no different from the ancestors of the Spaniards and other Europeans, who had also been barbarous and non-Christian. Thus the Indians were capable of being civilized, which meant also becoming Christian. In the end, what justified Spanish claims was papal jurisdiction over infidels, and specifically Alexander VI’s bulls dividing the newly discovered lands between Spain and Portugal in the 1490s. Knowing the political and religious conflicts of the early seventeenth century, Solórzano sought refuge in a long-lived medieval theory of papal power— one that was, of course, unacceptable to Protestant rulers and even some Catholic ones. But even this papal authority was limited in regard to Spain’s political claims. Alas, in the real theater of power, neither the proud kings of Spain nor their adversaries would hold truck with such doctrines.

Muldoon has done an excellent job of summarizing, explaining, and contextualizing Solórzano’s views. Muldoon’s erudition and remarkable mastery of the development of legal thought allow him to restore Solórzano to the important role he played in the formulation of an international order in early modern Europe.