Slavery in Sixteenth-Century Spanish Scholastic Thought

Daniel Allemann

My doctoral research focuses on the notion of slavery in Spanish scholastic thought in the context of the broader question of the human in the sixteenth century. The members of the ‘School of Salamanca’ or ‘second scholastic,’ a group of early modern Spanish theologians whose work centered around the re-evaluation of questions initially raised in Thomas Aquinas’s Summa theologiae, famously engaged in the debate about the nature and the political status of the ‘barbarians,’ that is, of infidel peoples who had become known to the Spaniards in the course of their colonizing ventures in the New World. However, the theologians of the second scholastic also addressed the question of slavery as part of a discourse of commutative justice, the justice in inter-individual exchange and contracts. In this juridical perspective, they thoroughly theorized the morality and legality of driving oneself into slavery in cases of extreme necessity and of enslavement of the vanquished in a ‘just war.’ Under certain circumstances, they argued, human liberty could be traded for the preservation of one’s life. But what implications does it have if slavery becomes subject to an essentially economic thinking, a ‘moral economy’?


It is well-known that the early members of the School of Salamanca extensively discussed the question whether the Catholic Monarchs could justly enslave the ‘newly discovered’ American Indians. The Spanish scholastic intervention, led by Francisco de Vitoria, repudiated the idea that American Indians were what Aristotle had termed ‘slaves by nature’ and could therefore be legitimately dispossessed and dominated by the Spaniards.[1] This fundamentally contrasted with the Thomist-Aristotelian conception of humans as naturally free and political beings. Yet, the issue became more complex when pondering the questions whether slavery in extreme necessity or enslavement as a result of ‘just wars’ were permissible. While no human being could be a slave by nature, the question was whether the ius gentium or ‘law of nations,’ as a legal framework, allowed for slavery as a result of human agency. Traditional scholarship on the ius gentium in the second scholastic primarily celebrated such figures as Vitoria as progressive founders of international law.[2] More recent studies, however, have concentrated on the details of the neo-scholastic use of the ius gentium, stressing that the law of nations was closely connected to the institution of private property and contracts after the Fall.[3] Scholars have investigated the School of Salamanca’s development of a vocabulary of private rights over oneself and over external things, which could be alienated and transferred according to commutative justice, and which thus provided the foundation for inter-personal circulation of material things. In this vein, some of the most powerful readings reveal a post-colonial impetus, arguing that the neo-Thomist articulation of a system of global trade under the ius gentium is to be conceived as part of the history of colonialism and imperialism.[4]


The implications of the neo-scholastic emphasis on human agency to freely exchange goods while simultaneously understanding contracts in essentially moral terms have received considerable attention.[5] However, a sustained study on how slavery is situated within this ‘moral economy’ remains strikingly absent from this new perspective of approaching the thought of the School of Salamanca.[6] My doctoral research proposes to close this lacuna by tracing the discourse of slavery in sixteenth-century Spanish scholastic writings. In the first instance, I wish to explore how the Salmantine theologians situated their accounts of voluntary slavery and enslavement in ‘just wars’ within a broader nexus of property relations under the ius gentium, as part of an ‘empire of private rights.’[7] Secondly, I intend to analyze how this conception relates to discussions of natural slavery in the context of the Spanish conquest of the New World. How could slavery under the intricately connected frameworks of the ius gentium and commutative justice be reconciled with the natural condition of human beings as essentially free of domination? What is more, the immediate debates about the Spanish conquest and American Indians, which shaped the discussions of slavery by earlier members of the School of Salamanca, such as Vitoria or his pupil Domingo de Soto, were no longer an issue for later theologians such as Miguel de Palacios, Luis de Molina, or Francisco Suárez, who set their discussions in a greater framework, against the backdrop of the Portuguese slave trade. How, then, can the development of neo-scholastic writing about slavery in the sixteenth century be characterized? How did the Spanish scholastic theologians negotiate the tension between a theologically grounded human nature, private human rights, moral justice, and slavery? And, finally, to what extent could free human subjects be objectified and commodified under the status of slavery?


My proposed doctoral project develops my previous research into discourses of the humanity of American Indians in the second scholastic. In my MA thesis at the University of Basel I focused on texts by Francisco de Vitoria, Alfonso de Castro, Francisco Suárez and, briefly, Luis de Molina. Opposing a generalizing and monolithic view, I argued that neo-scholastic writing about American Indians consisted of a diverse range of creative constructions and deconstructions of the human, which resulted in negotiations of both the edge and the very essence of humanity. What is more, I have recently completed an MPhil dissertation on Luis de Molina’s treatise of slavery at the University of Cambridge. Building on this research, my doctoral project aims at offering a comprehensive study of the place of slavery in Spanish scholastic thought. Increasingly, importance is being placed on the neo-scholastics in the history of empire, colonialism, and systems of global trade, as much as in relation to questions of the origins of human rights.[8] My doctoral research therefore ultimately aims to refine our understanding not only of the School of Salamanca in itself, but equally within these wider trajectories.


[1] See Lewis Hanke, Aristotle and the American Indians: A Study in Race Prejudice in the Modern World (Bloomington: Indiana University Press, 1959); Anthony Pagden, The Fall of Natural Man (Cambridge: Cambridge University Press, 1982).

[2] See e.g. James Brown Scott, The Spanish Origins of International Law: Francisco de Vitoria and His Law of Nations (Oxford: Clarendon Press, 1934).

[3] See e.g. Annabel S. Brett, Changes of State: Nature and the Limits of the City in Early Modern Natural Law (Princeton: Princeton University Press, 2011).

[4] See Martti Koskenniemi, ‘Empire and International Law: The Real Spanish Contribution,’ University of Toronto Law Journal, 61 (2011), 1-36; Antony Anghie, Imperialism, Sovereignty and the Making of International Law (Cambridge: Cambridge University Press, 2004). Interestingly, in his most recent work, Anthony Pagden has also placed the School of Salamanca in a history of empire: Pagden, The Burdens of Empire: 1539 to the Present (Cambridge: Cambridge University Press, 2015).

[5] See Wim Decock, Theologians and Contract Law: The Moral Transformation of the ius commune (ca. 1500-1650) (Leiden: Brill, 2013); José Barrientos García, Repertorio de moral económica, 1526-1670: La Escuela de Salamanca y su proyección (Pamplona: Eunsa, 2011).

[6] The major exception is Matthias Kaufmann’s case study of slavery in the thought of Luis de Molina: see Matthias Kaufmann, ‘Slavery between Law, Morality, and Economy,’ in A Companion to Luis de Molina, ed. by Matthias Kaufmann and Alexander Aichele (Leiden: Brill, 2014), pp. 183-225.

[7] The phrase is Martti Koskenniemi’s.

[8] See Annabel Brett, ‘Human Rights and the Thomist Tradition,’ in Revisiting the Origins of Human Rights, ed. by Pamela Slotte and Miia Halme-Tuomisaari (Cambridge: Cambridge University Press, 2015), pp. 82-101; see Samuel Moyn, The Last Utopia: Human Rights in History (Cambridge, Mass.: The Belknap Press of Harvard University Press, 2010).