2.3.1 Legitimising Slavery During the Atlantic Slave Trade: Continuity from Beginning to End

Starting from the fifteenth century, lawyers had a new challenge in the legitimation of slavery. Portugal and Spain were the first major powers to explore the Atlantic in that century.

The Spaniards were hardly the only ones to be faced with the legitimacy of slavery. If sixteenth century theorists such as Pierino Belli and Alberico Gentili primarily discussed slavery in the context of just wars between European powers, seventeenth and eighteenth century theorists of international law faced a different reality. If Spain’s “question” had largely been related to Indian slavery, all of the main European powers were heavily involved in draining a new source of slaves. Black Africans were brought en masse to the Americas to serve European masters. How did the Classics legitimise the Atlantic slave trade?

The Classics were also concerned with a fundamental issue that had been touched on from Antiquity onwards, namely the distinction between ius naturale and ius gentium.

2.3.1.1 From Indians to Blacks: Victoria and Suarez

Franciscus de Victoria (1483–1546) took up the Chair in Theology at the University of Salamanca in 1526, and is considered by James Brown Scott as the true “father of international law”.¹⁴⁷ On slavery, his work is centred on the “Indian question”.

Without going into detail, Victoria’s works have to be seen within the context of this “Spanish struggle for justice in the conquest of America”, as Spanish theologians and lawyers alike wrestled with the question of the legitimacy of enslaving the native American population.¹⁴⁸ It was a contemporary of Victoria, Friar BartolomĂ© de Las Cases (1484–1566), who became most famous for his defence of the Indians. At the height of the controversy, this led to the famous (but largely inconclusive) “Valladolid debate” between de Las Casas and the Spanish humanist Juan GinĂ©s de SepĂşlveda (1494–1573), a proponent of natural slavery.¹⁴⁹

In his De Indis, Victoria started by mentioning the idea that the Indians were true owners in public and in private law before the Spaniards had arrived. He continued by using Aristotle’s theory of natural slavery in a curious way. According to him, Aristotle did not mean that “those who are not over-strong mentally are by nature subject to another’s power and incapable of dominion alike over themselves and other things”, but rather “that by defect of their nature, they need to be ruled and governed by others”. He equated the situation with that of a son who is subject to his parents until he reaches the age of majority, or of a wife to her husband.¹⁵⁰ In other terms, Victoria held that whereas it was not permissible to seize the patrimony of the Indians and enslave them without a reason, it would be “wise” if they were to be ruled and governed by the Spaniards.¹⁵¹ This is followed by two sections in which Victoria deduced both the titles which he deemed illegitimate to reduce the Indians to slavery, and the titles which might have been legitimate. In each of those cases, he did not make a pronouncement whether a legitimate reason was actually present in the case at hand. Out of the eight possible legitimate reasons, it is most noteworthy that Victoria accepted the legitimacy of just war theory itself (his first possible legitimation).¹⁵² For present purposes, it is also interesting to see that, even though Victoria believed that the Indians were no natural slaves, he did not deny the validity of Aristotle’s natural slavery thesis itself.

If slavery was at the centre stage of Victoria’s work, it was not anymore in Francisco Suarez’ (1548–1617) thinking. At the time of writing, Spain had started to make the change towards a regime of African slave labour. In comparison with the discussions on Indian slavery, it is astonishing to see how the legality of the African slave trade was routinely ignored by the Spaniards. Seymour Drescher noted the curious case of King Philip II of Spain, who consulted theologians in 1553 to address the lawfulness of the regime that Spain used to procure slaves, the so called Asiento de negros. In its essence, this was a system of trade monopoly licenses that allowed private companies to bring slaves to the Spanish colonies.¹⁵³ The theologians discussed the justice of a state monopoly and the rate of profit that was given to the license holder. However, nothing was to be found about the justice of the slave cargo itself.¹⁵⁴

This same idea of casual neglect can be found when reading Francisco Suarez’ discussion on slavery. Acknowledged as being the “last of the Scholastics”, Suarez, in his 1612 work De Legibus, Ac Deo Legislatore, refrained from the sweeping discussions on slavery that had typified his predecessor Victoria. Slavery simply served as an example in Suarez’ discussion on natural law and ius gentium, the institution of slavery falling squarely within the latter. While acknowledging that slavery was not part of natural law, he did accept that the ius gentium itself, as established through the habitual conduct of nations, was quite in accord with nature.¹⁵⁵

2.3.1.2 Belli, Ayala and Gentili: Writers in the Law of War Tradition

These three authors can be seen as part of the same tradition, as Pierino Belli, Balthazar Ayala and Alberico Gentili all wrote their works on the laws of war. When dealing with this topic, as medieval writers did before, they were obviously confronted with the issue of slavery.

Pierino Belli (1502–1575), an Italian, wrote his work De Re Militari et Belli Tractatus in the service of King Philip II of Spain in 1563.¹⁵⁶ Whilst his work focused on the European context, he did notice the issue of the Spanish enslavement of the Indians.

Balthazar Ayala (1548–1584), a Spaniard who was born in Antwerp and who studied at the University of Leuven, also wrote his work De Jure et Officiis Bellicis et Disciplina Militari Libri Tres while in the service of the Spanish army. He should still be seen as belonging to those scholars upholding the substitutionist (those who conceived of the conception of the ius gentium as a debased form of ius naturale) relationship between the ius naturale and the ius gentium, which is visible in his treatment of slavery.¹⁶⁰ In a chapter “Of Capture in War and the Law of Postliminy”, Ayala questioned whether slavery should be seen as part of the ius naturale or the ius gentium. He believed the latter to be the correct idea, as liberty is an institution of the law of nature. Slavery arose because of two reasons, namely that “the wickedness of man [in his fallen state] ought to be restrained by war and captivity and slavery”, and also because of “its utility to the State as a means of repressing those who wage unjust war”.¹⁶¹ This, however, only applied when dealing with a just war.¹⁶² Just like Belli, he noted the existing custom between Christians not to enslave each other during wars, but held that, in case Christians were fighting on the side of the Saracens and infidels against fellow Christians, the exception did not apply.¹⁶³

Alberico Gentili (1552–1608) was an Italian law professor who left Italy due to his Protestant faith and eventually became a professor of Civil Law at the University of Oxford.¹⁶⁴ His De Iure Belli Libri Tres was an inquiry into the circumstances in which war was justly undertaken, conducted and terminated.

2.3.1.3 Hugo Grotius and Slavery

Whilst the previous thinkers upheld the very broad overlap between ius naturale and ius gentium, this approach would increasingly start to change with Hugo Grotius (1583–1645), the first Dutch Classic. In Grotius’ thinking, law had to be divided in ius naturale and volitional law, “which has its origin in the will”.¹⁷¹ As before, the ius naturale remained the dictate of right reason. Volitional law had to be divided further in divine law and human law. In this last category, Grotius made yet another distinction between municipal law (the law of one state), law which was narrower than municipal law (e.g. the commands of the father) and the law of nations, his so called ius gentium voluntarium.¹⁷² It is this final category which would become increasingly important in the formation of international law in the next centuries.

In his De iure belli ac pacis, Grotius had much to say on slavery. Whilst Grotius, having worked in the service of the Dutch East India Company himself, was certainly aware of the nascent Dutch slave trade, it was not the case that the Dutch had already become major players in the slave trade at the time of publishing in 1625.¹⁷³ Grotius’ views on slavery are divided in three chapters (Book II, Cap. V; Book III, Cap VII and Cap. XIV).

Grotius acknowledged that, according to nature, no one can be a slave, thereby distancing himself from Aristotle’s position.¹⁷⁴ At the same time, he said that it was not against nature if a man voluntarily subjected himself into complete slavery, with the underlying idea being that the slave owed lifelong service to his master in return for nourishment and other necessities of life.¹⁷⁵ Individuals, who have the natural right of liberty, also have the liberty of placing themselves in voluntary servitude. On the basis of consent, a master could thus derive a valid title to a slave.¹⁷⁶ Grotius went even further when discussing the legality of slavery under the ius gentium voluntarium. Here, he believed that during a formal public war, not only all those who surrendered themselves, but all without exception who were captured within enemy lines could be regarded as slaves. The same held true for the descendants of persons captured in war.¹⁷⁷ For legitimation, Grotius referred, among others, to Florentinus’ statement on slavery as servare (to save) of those who would otherwise be killed.¹⁷⁸ As we have seen with the previous Classics, Grotius did acknowledge that this provision did not have force of law anymore during wars amongst Christian nations.¹⁷⁹

All this shows Grotius’ extended views on the legality of slavery. There is no proof that Grotius wrote his views with the Dutch West India Company and East India Company slave ventures in mind. But Cairns convincingly argued that, at the least, Grotius’ work could and would be used later on by the maritime colonial powers as a valuable tool to support the legality of the transatlantic slave trade, as his work provided the perfect legitimation.¹⁸⁰

2.3.1.4 Grotians and Hobbesians: Different Approaches, Same Belief in the Legitimacy of Slavery

Grotius’ fundamental distinction in “two types of international law” would come under severe scrutiny by Thomas Hobbes (1588–1679). In Leviathan, the innate sociability of the human race, always closely connected to ius naturale, was rejected. Hobbes’ worldview was one in which humanity strived towards a rational pursuit of its self-interest. His version of natural law boiled down to a fundamental right of personal security and a fundamental duty of the performance of agreements (pacta sunt servanda).¹⁸¹ For our purposes, the most important thing to remember is that out of Hobbes’ observations, the conviction grew amongst some scholars that the sole legal tie between states was provided by ius naturale, not ius gentium. That is why in the seventeenth and eighteenth century, some Classics would agree with Grotius that both ius naturale and ius gentium were valid sources of law for the conduct between states (“Grotians”), whereas the “Naturalists” would assert that it was only the ius naturale that was binding law of general application between states.¹⁸²

It is in the category of the Grotians that we can find three seventeenth century Classics, namely Richard Zouche, Samuel Rachel and Johann Wolfgang Textor.

Richard Zouche (1590–1661) was a British contemporary of Hugo Grotius who also held the Regius Chair of Civil Law at the University of Oxford. His most famous treatise was the 1650 Juris et Judicii Fecialis, sive, Juris inter Gentes et Quaestionum de Eodem Explicatio, in which he discussed the relationship between states during war and peace.¹⁸³ His treatment of slavery was very short, part of the section “Of Ownership among Belligerents”. Slavery is seen as part of the ius inter gentes, and Zouche made references to Aristotle (not in the context of slavery as part of the ius naturale) and Gaius. Once more, the fact that Christian nations had changed to the practice of ransoming, instead of enslaving fellow Christians, was mentioned.¹⁸⁴ Zouche thus limited himself to the European context but did not say anything directly about the nascent transatlantic slave trade.¹⁸⁵

Samuel Rachel (1628–1691) and Johann Wolfgang Textor (1638–1701) were two German Classics, the former working as Chair in International Law at the University of Kiel, the latter as the Chair of Jurisprudence at the University of Heidelberg. Rachel had very little to say about slavery in his 1676 De Jure Naturae et Gentium Dissertationes, simply stating that “Those who surrender in such a war [a just war], or accept terms of slavery, or are captured, become the slaves of the victors by the Law of Nations”. The same treatment was accorded to descendants of female slaves. Finally, Grotius was quoted on the fact that slavery had “long since fallen into desuetude” among Christians prisoners of war.¹⁸⁶

Textor, in his Synopsis Juris Gentium of 1680, paid attention to slavery. As had become habitual by now, he noted how slavery had become a rule of the ius gentium after it was found harsh and brutal to kill all those who had fallen into the enemy’s hands. He was more precise than some of his predecessors about the exception to enslavement in wars among Christians, observing that this exception had been introduced “about three hundred years ago”.¹⁸⁷ He added that the same did not apply in wars “of the Turks and of other barbarians”, on the basis of reciprocity.¹⁸⁸

In stark contrast to the previous writers, we find Samuel Pufendorf (1632–1694), the seventeenth century German historian and lawyer who wrote his De Iure Naturae et Gentium in 1672 whilst holding the Chair of the Law of Nature and of Nations at Lund University.¹⁸⁹ In Pufendorf’s view, only ius naturale could serve as a source of constraint upon states in their relations with each other. He did acknowledge the existence of treaties and customary law, but their importance was limited. The former was nothing more than a private contract between states, and ignoring custom was not seen as a breach of a binding obligation.¹⁹⁰ Slavery was discussed as a separate chapter “On the Power of a Master”. Although Pufendorf agreed with Aristotle that “some are so stupid that they do not observe, without the lead of others, what will be of use to them” (Aristotle would call such persons natural slaves), he did reject the view that slavery was established by the ius naturale.¹⁹¹ According to Pufendorf, the origin of slavery started in the early days of mankind, when poorer people started hiring themselves out to others (“And so the first beginnings of slavery followed upon the willing consent of men of poorer condition, and a contract of the form of “goods for work”: I will always provide for you, if you will always work for me”).¹⁹² In later times, slavery would then become customary (and in Pufendorf’s framework thus not binding law between states) during wars. Afterwards, slavery was also introduced for the children of the captives and for those who wanted to sell themselves. Pufendorf did mention that slavery was later restricted, and in some states entirely removed, but did not provide further clarification.¹⁹³

2.3.1.5 Eighteenth Century Classics: Modest Acknowledgement of the Atlantic Slave Trade, First Moral Concerns

Our final three thinkers, Cornelius van Bynkershoek, Emmerich de Vattel and Christian von Wolff, are to be placed in the eighteenth century. By this time, the French, Dutch and English had decisively broken the Iberian monopoly in the Atlantic world and had developed extensive slave colonies themselves.¹⁹⁴

In comparison with Hugo Grotius’ elaborate discussions, Cornelius van Bynkershoek (1673–1743), the eighteenth century Dutch judge, had far less to say on slavery in his Quaestionum juris publicis libri duo.¹⁹⁵ His discussion on slavery started with the by now oft-discussed statement that slavery succeeded the right of slaying the captured enemy. He made a distinction between Christian nations, where slavery had fallen into disuse and where it was no longer employed against captives of war, and other cases. As for these other cases, he first discussed wars against Islamic states, with enslavement being allowed on the basis of reciprocity. Finally, he mentioned how the Dutch used slaves in Asia, Africa and America.¹⁹⁶ Out of this, Allain discerned that, for Bynkershoek, the law of nations precluded the enslavement of Christians and allowed for the enslavement in terms of reciprocity against Islam but was silent with respect to the situation in Asia, Africa and the New World. Interestingly, this is the first explicit acknowledgement by one of the Classics of black slavery beyond the frontiers of Europe.¹⁹⁷

Christian von Wolff (1679–1754), whilst a Grotian, was one of the eighteenth century thinkers who still devoted most importance to the ius naturale as the law governing interstate relations.¹⁹⁸ Working at the University of Halle, he composed his Jus Gentium Methodo Scientifico Pertractum in 1749. His treatment of slavery was twofold, forming part of his chapter “Of the Law of Nations in War”. Wolff acknowledged the right to capture enemies and soldiers during a just war, based on the idea that such persons were resisting the restoration of another state’s legitimate rights, and because these persons prevented the end of the war.¹⁹⁹ However, by the ius naturale, these captives did not become slaves. He believed that there was only a right to detain the captives until the war was over, and that an individual captive could only be reduced to slavery if he had committed an offence “worthy of that punishment”.²⁰⁰ Later on, he questioned how the sovereignty of so-called slave-kingdoms, which can be understood as kingdoms beyond Europe, could be acquired.²⁰¹ Such places, where all subjects were reduced to personal servitude, could only be captured through occupation in a just war.²⁰²

Finally, Emmerich de Vattel’s (1714–1767) Le Droit des Gens, ou Principes de la Loi Naturelle, appliquĂ©s à la Conduite aux Affairs des Nations et des Souverains (1757) merits our attention. Substantively, Vattel used much of Wolff’s theoretical framework for his own work. However, as he explicitly intended his work to be useful for practical purposes, he ensured that Wolff’s man-made law was explored more extensively.²⁰³ Slavery was discussed in his treatment of the right to make prisoners of war. During wars, he believed that parties may lawfully capture all the subjects of the enemy state and make them prisoners. From the moment of surrender, the capturer is however faced with several limitations as to what he could do with the enemy. He could not kill the prisoner, unless he had committed a crime deserving that punishment (and, on the same account, the treatment accorded to a prisoner should be humane).²⁰⁴ For slavery, the same provision applied: unless the prisoner was guilty of a crime deserving of death, he could not be enslaved. Slavery was seen as little better than taking someone’s life for Vattel, who held that slavery condemned a person to a lot which was utterly at variance with man’s nature. Interestingly, Vattel finished with a remark which we have not seen hitherto: a disgust of slavery itself: “As it is, that reproach to mankind has happily been banished from Europe”.²⁰⁵

2.3.1.6 Conclusion: Continuity in the Legality of Slavery, Silence on the Atlantic Slave Trade

Clearly, none of the Classics denied the legitimacy of the institution of slavery. Some of them, such as Grotius and Pufendorf, even came quite close to Aristotle’s theory of natural slavery. Even Emmerich de Vattel, himself clearly repulsed by slavery, did not deny its legitimacy. At the least, all Classics accorded a place to slavery in a just war, though they were equally clear about the exception to this rule in wars between Christian states. Compared with the legitimation of slavery given by Aristotle or the Digest, there is a remarkable amount of continuity.

It is surprising to see that authors such as Grotius and Pufendorf had that much to say about slavery, given that the institution had already disappeared from the areas where they lived for several hundred years. This can only mean one thing: that, implicitly, the Classics were taking the transatlantic slave trade into account, and their work undeniably helped in providing a rationale for it.²⁰⁶ That being said, besides allowing for slavery, the Classics did not provide any substantive rules on the conduct of states in their operations in Africa. Quite possibly, the fact that slavery as an institution was legitimised, but African slavery itself was not explicitly addressed, can be easily explained. In contrast to what the Portuguese attempted for some time, the other major European powers would not do the enslaving of Africans themselves. Instead, they were happy enough to have trade access to the continent and export Africans, who were already enslaved in Africa by fellow Africans, to their colonies. If the institution itself was legitimate, the moral burden of legitimacy of the enslavement process itself could easily be diverted towards Africa.²⁰⁷

More than one eyebrow should thus be raised when reading what the last Classic, Henry Wheaton (1785–1848), wrote about the prohibition of the slave trade in his 1836 Elements of International Law. He claimed that the African slave trade “had been at all times regarded by just and enlightened men as repugnant to the principles of humanity and universal morality”.²⁰⁸ Many of his fellow Classics would undoubtedly have begged to differ.