Hobbes and Leibniz on the Nature and Grounds of Slavery

In: Hobbes Studies
Iziah C Topete Department of Philosophy, Penn State University, State College, USA

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During a period when transatlantic slavery was still being racialized, Hobbes and Leibniz represent stark alternatives on the nature and justification of slavery. This article investigates Leibniz’s encounter with the Hobbesian position on slavery (servitus), drawing out the racial implications. Throughout his political works, Hobbes defended voluntary servitude by transforming a legacy of Roman jurisprudence that had come to be encapsulated in the law of nations (jus gentium). Hobbes defended the justification that a master could possess slaves as de jure property with the rights to buy or sell them. In Sur la notion commune de la justice, Leibniz argued against Hobbes that slave-owners’ rights should be limited. He also defended his own paternalistic justification of slavery, reinterpreting Aristotelian natural slavery. Leibniz claimed that some persons merit guidance as slaves by nature, yet legitimate possession of persons can only go as far as a usufruct. In contrast, Hobbes had rejected the normative logic that any person could rationally merit enslavement but maintained that masters could totally possess the body of captive slaves for as far as their power extends.


During a period when transatlantic slavery was still being racialized, Hobbes and Leibniz represent stark alternatives on the nature and justification of slavery. This article investigates Leibniz’s encounter with the Hobbesian position on slavery (servitus), drawing out the racial implications. Throughout his political works, Hobbes defended voluntary servitude by transforming a legacy of Roman jurisprudence that had come to be encapsulated in the law of nations (jus gentium). Hobbes defended the justification that a master could possess slaves as de jure property with the rights to buy or sell them. In Sur la notion commune de la justice, Leibniz argued against Hobbes that slave-owners’ rights should be limited. He also defended his own paternalistic justification of slavery, reinterpreting Aristotelian natural slavery. Leibniz claimed that some persons merit guidance as slaves by nature, yet legitimate possession of persons can only go as far as a usufruct. In contrast, Hobbes had rejected the normative logic that any person could rationally merit enslavement but maintained that masters could totally possess the body of captive slaves for as far as their power extends.


Commentators have noted Leibniz’s encounter with Hobbes’s political thought.1 What has received little scholarly attention is Leibniz’s engagement with Hobbes on the issue of slavery or servitude (servitus), especially in the wider context of transatlantic slavery.2 At the outset of the 18th century, Leibniz wrote two works on the nature of justice and both of them addressed Hobbes extensively: Sur la nature de la bonté et de la justice (c. summer 1703) and Sur la notion commune de la justice (c. 1703).3 It is within the latter work that Leibniz addresses ownership of persons as de jure property. He engages with Hobbes’s arguments on the possibility of an absolute right over persons. Leibniz’s immediate concern in the text is the metaphysical ground of goodness and justice and accordingly whether their foundation is something arbitrary or eternal, akin to a mathematical common notion. His overall aim is to defend a universalist conception of justice that he defines as the charity of the wise (caritas sapientis).

I present Leibniz’s encounter with Hobbes as a historical case study on how de jure slavery was conceptualized, justified, and disputed. Leibniz illuminates the distinctive legacy of Hobbes’s arguments on slavery, servitude, and dominion. This text also reveals what Leibniz knew about the conceptual landscape surrounding slavery within Europe – especially during a period when the transatlantic slave trade was in the process of growth. In this last respect, I aim to make explicit the racial import of this debate over slavery.

In the span of a couple of pages within Sur la notion commune de la justice, Leibniz passes over an array of intersecting topics:4

  1. (1)The grounds for Hobbes’s claim that a master (dominus) can possess an absolute right over another person and the seemingly equivalent status of children, servants, and slaves.
  2. (2)The law of nations (jus gentium) taken as justification for the enslavement of persons as captives from a just war – which stems from a legacy of Roman jurisprudence and was appropriated by legal philosophers such as Hugo Grotius and Samuel von Pufendorf.5
  3. (3)The rights over another person as a rational, embodied soul: whether de jure possession extends as far as usufructuary rights or if it entails the Hobbesian (and neo-Roman)6 definition of ownership as entailing “the right to dispose of a man’s person,” their body, property, and labor.7
  4. (4)Whether ownership of persons is ethically comparable to American cannibalism.
  5. (5)Finally, the possibility that some persons merit to be slaves, stemming from a tradition of natural slavery according to Aristotle’s account in Politics I.4–7.

I will reconstruct a dialectic between Leibniz and Hobbes to elucidate their disagreement over the nature of slavery and its justification. Leibniz is critical of Hobbes for defending the possibility of ownership of persons and their bodies. Even so, Leibniz goes on to justify the position that some persons merit enslavement as slaves by nature. He defends this position in various texts and as late in his life as 1712. His justification rests on a two-fold conception of rationality. First, all rational souls per se are bound by the universal justice actualized by God and by moral necessity have proprietorship over their own body. Yet, in a second sense, some persons fail to actualize their rational nature and so distributive justice requires that such persons deserve to be guided by someone wiser. It is in this respect that Leibniz sides more with Aristotle than Hobbes in denying the natural equality of human beings and holding instead that “government belongs to the wisest.”8

This article proceeds as follows. (§1) I first discuss how Hobbes fits into Leibniz’s aims within his own writings. (§2) I determine what is correct about Leibniz’s assessment that Hobbes defends the ownership of persons following from a tradition of Roman jus gentium. Leibniz is correct that a conquered servant and a bounded slave can both be possessed as de jure property by a dominus. Second, captive slaves and slave-children do not own their bodies since they are under the de facto power of a dominus and, so, slaves can be bought and sold as if they were non-rational animals.9 What Leibniz overlooks is how Hobbes distinguishes between servants and slaves in terms of entrustment of bodily liberty, as well as the theory of authorization that is unique in Leviathan (1651/1668). Hobbes differentiates himself from the original Roman account of slavery in theorizing trust and authorization. (§3) I present Leibniz’s critique of Hobbes and jus gentium on the ownership of persons. Leibniz argues that legitimate possession over a person is limited to a usufruct. God, as a perfectly wise and just sovereign, institutes rational souls as the sole proprietors over their bodies. (§4) I address Leibniz’s reinterpretation of Aristotelian natural slavery. The deepest disagreement between Leibniz and Hobbes is that Hobbes strips the Roman justification of slavery from its normative dimensions, as Deborah Baumgold has observed.10 There is simply no standpoint from which to argue on Hobbesian premises that a person could rationally merit their position as either dominus or servus, as Leibniz argues. (§5) I end by considering the transatlantic context, speculating on how the dialectic between Hobbes and Leibniz makes manifest different intellectual legacies in conceptualizing slavery in its entwinement with race.

1 Hobbes in Leibniz’s Sur la notion commune de la justice

Throughout his essay on justice, Leibniz engages with Hobbes in asking whether an agent can rightly possess an absolute right over persons. He frames Hobbes, along with Robert Filmer,11 as defending the “alleged absolute right [pretendu droit absolu] of masters over slaves, or of parents over children.”12 What Leibniz has in view are Hobbes’s claims on the right of acquisition as they occur in Ch. 20–21 of Leviathan, with parallel arguments in Ch. 8–9 of De cive (1642) and Ch. 22–23 of The Elements of Law (1640). It is essential to recognize that Leibniz couches his discussion of slavery, along with the question of parental dominion, within his metaphysical framework of divine justice. When writing on justice at the outset of the 18th century, Leibniz was simultaneously shifting his concerns from a dynamic theory of force to a monadological metaphysics. Justin Smith has situated Leibniz’s arguments about political domination over persons in terms of his theory of monadic domination, beginning from his letter to Burchard de Volder in June 1703.13 As I will show, the significance of Leibniz’s metaphysics to slavery revolves around how a rational soul qua intelligent monad can be said to possess its own body.

Leibniz first introduces Hobbes, along with the possibility of possessing an absolute right over another, by entertaining whether an agent with unlimited power – une puissance Superieure – would be bound to observe any form of justice in their treatment of others.14 Hobbes describes this agent as having “Irresistible Power.”15 Leibniz examines what he takes to be three Hobbesian premises. First, outside of the commonwealth and in the state of nature, and as abstracted from all superiors, there is no binding justice.16 This sense of nature corresponds to what Al Martinich marks as the “primary state of nature,” since the “secondary state of nature” implies divine commands.17 Second, justice is ultimately grounded by power (potentia) or what an agent can effectively bring about de facto. Finally, all action is motivated by perception of one’s own good or self-interest.18 Leibniz reasons that if all these Hobbesian premises are granted, then it follows that an all-powerful agent would have no moral obligations to others and that such an agent may do as they like arbitrarily. In contrast to the case of agents of similar capacities compacting with each other to bring about a civitas, Hobbes had granted in Ch. 31 of Leviathan:

… if there had been any man of Power Irresistible; there had been no reason, why he should not by that Power have ruled, and defended both himself, and them according to his own discretion.19

Accordingly, Leibniz primarily disputes the second premise regarding justice and, by extension, the first premise, by appealing to what we can rationally discern about God. He claims that “justice is nothing else other than what is in conformity to wisdom and goodness joined together,” exemplified by the benevolent charity of the wise.20 Later, in his Theodicy (1710) Leibniz writes that God’s “power is indeterminate, goodness and wisdom combined determine him to produce the best.”21 Since God is determined to choose the best, then his power alone does not explain his rational choice. God’s power, goodness, and wisdom unite to constitute an essentially just will.

Leibniz conceives of universal jurisprudence as consisting in three grades of natural right paired to three types of justice. All three types are relevant in addressing slavery and in his critique of Hobbes. But Leibniz begins methodologically by granting the premise of psychological egoism so as to persuade the Hobbesian to recognize higher types of justice. He writes, “Hobbes seems to conceive that men were something like animals [bestes] at first.”22 So Leibniz first considers our bare rights such as the right to self-preservation. However, moving past this state, we advance to higher degrees of natural right and forms of justice as follows.

  1. (1.1)The strict rights that we share equally with others in commutative justice, i.e., jus strictum.
  2. (1.2)The rights of equity that follow from the differences amongst human beings in terms of their normative merit and demerit according to distributive justice.
  3. (1.3)Finally, the universal justice that follows from God as an essentially just agent and human persons as rational, immortal souls.

In light of the universal justice instituted by God and our immortal nature, then “everything honorable is useful and everything base is damned.”23 Bringing about the good for others is in fact identical with pursuing one’s own good. Leibniz maintains that Hobbesian self-interest as a motivational ground is harmonious with the normative demands of disinterested love and justness, claiming that “whoever, indeed, does good out of love for God or of his neighbor, takes pleasure precisely in the action itself (such being the nature of love) and does not need any other incitement, or the command of a superior.”24 Thus, starting with a Hobbesian premise, Leibniz comes to an anti-Hobbesian conclusion: agents are bound in a morally significant way in their treatment of others, i.e., to take pleasure in bringing about the good and perfection of others in loving charity.

All rational agents, thus, are morally bound to justice. For universal justice is constitutive of our world as the best possible world and as a world perpetually progressing to what ought to be. Leibniz accordingly charges Hobbes with confusing what an agent can do (potentia) with what is rightfully owed in terms of justice. He leverages this insight against Hobbes onto the issues of slavery and the extent to which one can rightfully possess another person, their body, property, and labor. According to Leibniz, Hobbes simply confines himself to the “right of acquisition” as a strict right (jus strictum).25 Leibniz argues that this jus strictum of acquisition is limited by the higher rights of equity in distributive justice and piety in universal justice.26 This position on natural right bears on why he diverges from Hobbes in conceiving the nature of slavery, its ethical limits, along with the justificatory grounds for enslavement. As I will show in the third section, Leibniz argues for the position that ownership of a person is de jure impermissible since rational souls are the sole proprietors of their own bodies.

2 Hoc meum est: Persons as Property

In this section, I reconstruct why Leibniz takes Hobbes to be the preeminent defender of the thesis that all forms of sovereignty are at bottom nothing but a relation between dominus and servus. Leibniz accordingly interprets the Hobbesian position to bear not just on absolute authority (summa potestas) but also on chattel slavery in the sense that one could attain property rights over another person. Recently, Daniel Lee has argued that “Hobbes seems to think that all states, of all varieties, are structures of dominium,” which supports Leibniz’s assessment.27 Still, what Leibniz overlooks is how Hobbes transforms the Roman justification of slavery.

Hobbes defends the justification that a dominus can acquire “property or dominion, over the person of another.”28 Keeping in view what Leibniz cites and read by 1703 – as he does not seem to cite the Elements29 – he knew of Hobbes’s defense of servitus in De cive Ch. 8.5:

A Master therefore has no less right and dominion over the unbound slave than over the bound, for he has supreme dominion over both; and he may say of his slave no less than of any other thing, animate and inanimate, This is mine. It follows that anything that belonged to the slave before enslavement belongs to his Master afterwards, and anything the slave may acquire is acquired for the Master. For he who has the right to dispose of a man’s person as he pleases also disposes of all the things the person could dispose of.30

Within this passage, Hobbes deduces the right of dominion over both a conquered, unbounded servant and a bounded slave by appealing to the power of the dominus over them. Second, a dominus can possess servi to such a degree that proprietorship over them is equivalent to de jure ownership of an inanimate thing. Third, a dominus has the right to dispose of the personhood of servi.

Hobbes does not go into detail regarding the full scope of this right to dispose of a person as property. One plausible interpretation of this claim is that a dominus has all-encompassing rights over servi. That is, a dominus has rights over the body, property, labor, and personhood of their servi. Servi can possess nothing of their own against a dominus, even themselves as a person. The relation is entirely unilateral in favor of the dominus and so the dominus does not need to recognize their servi as moral agents. For this reason, a dominus has the right to sell their property rights over their servi and give them away as necessary and without prior consent from their servi.31

What sustains this unilateral relation of a dominus over a servus is “by power and natural strength” (potentiâ et viribus naturalibus). 32 The same logic applies to the cases of rational persons over non-rational animals or a mother’s ownership of her child.33 For what undergirds all these relations of ownership, as Laurens van Apeldoorn observes, is that Hobbes is committed “to the transitivity of potentia.”34 For example: “if a mother has been captured in war, her offspring belongs to her captor, because he who has Dominion over a person has Dominion over everything that is hers; and that includes the child.”35 In the case of physical capture of a mother, the new dominus with potentia comes to possess all that the mother ever had, including ownership of her offspring. Hobbes makes the same argument regarding slavery: if a slave-master were to become captured, ownership would transfer to the new dominus given the transitivity of potentia.36 The new dominus has the right to dispose of the man’s person in whatever way they like.

Hobbes’s account of slavery is abridged within Leviathan, yet his reasoning is seemingly unaltered.37 He argues that “Slaves that work in Prisons, or Fetters, do it not of duty, but to avoyd the cruelty of their task-masters.”38 That is, a slave has no obligation to their dominus, so each can kill each other as they see fit, and thus there exists no trust between them. Ultimately the lives of slaves depend on “the Will of their Masters.”39 Hobbes concludes that captive slaves and slave-children do not possess their own bodies because they are under the absolute power of a slave-master. Hence, captive slaves and slave-children can be “bought and sold as Beasts.”40 In this regard, Leibniz is accurate to foreground the role of potentia across Hobbes’s accounts of de jure servitude and de facto slavery.41

Correspondingly, Leibniz reasons from what he read from Hobbes in De cive and Leviathan that an agent with unlimited potentia over us “will have an absolute right over us after he conquers us.”42 On the basis of the right of acquisition, he writes “Hobbes believes that by virtue of this right, children are the property of the mother.”43 Leibniz pushes back and states that he does not believe potentia over a person can ever make it justified that “children are the property of their progenitors, as are our horses or the dogs which are born to us, or as the works which we make.”44 He then entertains an objection: “It will be objected against me that we can acquire slaves, and that the children of our Slaves are slaves as well: now according to the law of nations [droit des gens] Slaves are the property of their masters” – slaves that have been “purchased or captured.”45 In these passages, Leibniz understands the Hobbesian position to reduce all relations to one of dominus-servus and as all legitimated by potentia. Furthermore, he associates this line of justifying possession of slaves as de jure property with the law of nations (jus gentium).46

Regarding the connection between Hobbes and jus gentium, Hobbes states in the Elements that the practice of servitus “was amongst the Romans, so it was amongst other nations.”47 Van Apeldoorn notes that Hobbes might have been exposed to the Roman account of acquiring dominion through physical possession from either Henry de Bracton or Grotius’s Mare liberum (1609).48 He had access to Grotius’s De jure belli ac pacis (1625) in the Hardwick library.49 Grotius recapitulates Florentius’s claim about slavery in the chapter “Of the Right over Prisoners” in Book iii.50 There are no persons that are slaves by nature since all persons are originally born free. But there are persons that become rightfully slaves in accordance with “natural justice” (justitiae naturali). 51 Hobbes’s argument in The Elements and De cive that the right of dominion over animals and persons follows from “natural strength” aligns with the account given by Gaius.52 Gaius states that, following on the basis of jus gentium, we have the right to acquire dominium over things and things are ours insofar as they are “governed by our control” (custodia coercetur).53 Hobbes’s position on captive slaves is also parallel to the claim made by Gaius that a dominus can possess the “power of life and death” over their slaves.54

In two crucial respects, though, Hobbes expressly differed from the Roman view throughout his political works. First, observing that the Romans made no formal distinction between slaves and servants, “but comprehended all under the name of servus,”55 he instead distinguished between the two. For the right of dominion over conquered servants follows from consent, which originates from fear and the threat of physical control. The conquered servant receives the “sparing of his life” (est vitae condonation) following from a dominus entrusting them with corporeal freedom.56 In virtue of such a moral relation between a dominus and conquered servant, the obligation on the part of servants lasts only as long as power and protection persist. In contrast to a conquered servant, a captive slave remains in perpetual fear of death because there is no trust between him and his slave-master. Thus, the distinction between de jure servitude and de facto slavery is born out of a relation of trust.

Second, within Leviathan Ch. 20.13, Hobbes justifies the right to dispose of a servant on the basis of his theory of authorization. That is, the normative ground of a master’s right over a servant is in virtue of the servant’s “covenant of obedience,” and so “of owning, and authorising whatsoever the Master shall do.”57 Accordingly, a master is authorized by their servant to kill them, cast them into bonds, or punish the servant if the servant would disobey their master. The servant, because of their political contract, identifies with the actions of the master. The ultimate author of such actions is in fact the servant himself.

Ignoring the roles of trust and authorization, Leibniz saw the Hobbesian position as amounting to a particular neo-Roman justification of slavery.58 He judged the logic of ownership and property rights over personhood to be valid targets insofar as they involve the idea of absolute right over persons. Thus, as we have seen, Leibniz’s philosophical target in Sur la notion commune de la justice is not limited to Hobbes’s conceptions of power and justice. He is also critiquing Hobbesian philosophy for maintaining that slaves and their children lack ownership of their bodies, since a slave-master has corporeal possession of them, and that slaves can be bought and sold as if they were non-rational animals.

3 Rational Souls, Self-Ownership, and Divine Dominium

Leibniz wrote early in his life in Elementa Juris Naturalis (c.1669–1670): “therefore, if it is imagined that there is no God, nothing will be just beyond what Thomas Hobbes supports in De cive.”59 This claim takes on a novel significance with regard to the justness of slavery. That is, the absolute right of a dominus over servi is only apparent since Leibniz argues for higher degrees of natural right. He argues against the absolutization of a right of acquisition on metaphysical grounds: “one must assume the immortality of the soul, and God as ruler of the universe.”60 As he wrote in the Discours de metaphysique (1686), “we must join morals to metaphysics” and consider God as “the leader of all persons or intelligent substances and as the absolute monarch.”61

Leibniz begins the next stage of his argument in Sur la notion commune de la justice by granting a conditional justification of slavery according to jus gentium and natural reason, which we have reconstructed in a Hobbesian light. That is, he grants that a dominus has de facto possession of the bodies of slaves and their children, since they are under the physical power of the dominus. He writes: “I respond that even if I would grant that there is a right of Slavery among men in conformity with natural reason, and that according to the jus strictum, the bodies of slaves and of their children are under the power of their masters, it will still remain true that another stronger right is opposed to the abuse of this right.”62 Admittedly, in this passage, Leibniz focuses on the abuse (abus) of this right of acquisition, but his following argument will hinge around how there is in fact a stronger right that supersedes de facto corporeal possession.

Leibniz is not clear what this stronger right is and seems, possibly, to argue for multiple rights. A possible interpretation is the idea that, from the standpoint of universal justice, the right of acquisition over a person is superseded in light of God’s essentially just will – that is, his choice to actualize the best possible world in terms of universal justice and the subsequent intelligible harmony that binds rational souls to their bodies. By Leibniz’s account, “It is the right of rational souls who are naturally and inalienably free, [and] it is the right of God, who is sovereign master of bodies and souls, and under whom slave-masters are the fellow citizens of their slaves, since slaves have the right of citizenship in the Kingdom of God just as their slave-masters.”63

Leibniz makes three claims in this passage. First, rational souls have proprietorship over their own bodies. Second, there is implied a divine dominium thesis.64 The third concerns the moral equality of domini and servi as persons under God’s just governance. Together, the three claims undermine the Hobbesian position that a dominus can deprive a slave of their own body and hold the power to end their life as they see fit.

Correspondingly, Leibniz stands against the formulations of slavery given by Hobbes. A dominus cannot state to their slave, This is mine, in the sense of de jure ownership. More fundamentally, a dominus cannot exercise enough power over a slave to deprive the slave of proprietorship over their own body. Leibniz goes right to the heart of the matter by reassessing any form of possession of persons, writing “we can therefore say that the body of a man is the property of his soul, and cannot be taken away from him while he is alive.”65 Ultimately, “the soul cannot be acquired” so then “proprietorship [la proprieté] of his body cannot be acquired either.”66 The upshot is that it is a moral and metaphysical absurdity for a master to pretend either to have ownership over a slave or to deprive them of their body, which is the property of their rational soul. It is by a moral necessity that each of us as rational souls is constitutively bound to a body and subsequently has proprietorship over ourselves, i.e., self-ownership.

However, the scope of this self-ownership does not entail that we have absolute freedom, since God is still the sovereign master of bodies and souls.67 This divine dominium, the right of governance, is not grounded by omnipotence but because of God’s wisdom, goodness, and love for the whole of humanity. Regardless of whether a rational agent is in the state of nature or not – whether they are a master, slave, servant, or a child – they are all equally bound to the kingdom of God as citizens. Leibniz writes in Nouveaux essais (1704), “regard for God and immortality makes the obligations of virtue and justice absolutely binding.”68

In light of divine justice, any slave-master is limited in their treatment of slaves by moral necessity. First, the master owes to the slave moral recognition insofar as all persons are actualized as naturally and inalienably free by God.69 Second, masters are morally bound to respect slaves as equal citizens in the kingdom of God, which means that they ought to treat slaves as they wish to be treated.70 Third, a master is obligated to imitate the goodness of God and so perfect his moral agency, i.e., piety is an obligation.71

Leibniz draws the limits of what rightful possession of another person involves: “the right of the master over the slave can only be like what is called servitude on the land of another [le fonds d’autruy],72 or like a species of Usufruct.”73 As stated in the Digest by Paul: “Usufruct is the right to use and enjoy the things of another without impairing their substance.”74 Leibniz concludes: “Now usufruct has its limits – for it must be exercised salva re so that this right cannot go to the point of making the slave ill or unhappy.”75 In this respect, Leibniz conceives of this restricted form of servitus as a political condition in which a master acknowledges the slave as a full person, which means that the master recognizes that the sole proprietor of the body of the slave is their soul. In this case, the usufruct is the body of the slave. The master is granted the right to use the slave’s body as an instrument and can reap the fruits of their labor but cannot abuse their body. Though Leibniz permits a form of servitus as a usufruct, it is certainly not the Hobbesian slavery that entails the right to dispose of the person as property.

4 Rationality and Natural Slavery

Leibniz writes, from the position of universal justice, “we must also recognize that the entire universe is involved in a perpetual and most free progress.”76 But it would be too simplistic to end our study of slavery with Leibniz’s vision of perpetual progress over and against Hobbes. Early in his life, Leibniz forwarded colonialist and racialized arguments in the addendum to his Consilium Aegyptiacum (1671), where he discusses the possibility of the French colonizing and producing warrior slaves from Africa, Arabia, New Guinea, etc.77 But even in his later writings, the dialectic between Leibniz and Hobbes is serpentine due to Leibniz’s use of Aristotelian ideas of natural slavery. For throughout the early modern period, Aristotelian natural slavery was another line of justification for enslaving persons and was applied to both Africans and indigenous peoples from the Americas.

In both De cive and Leviathan, Hobbes straightforwardly mocks Aristotle for trying to justify the relation between dominus and servus by an appeal to their natures and differences in practical rationality, i.e., “by difference of Wit.”78 As we have seen, Hobbes forwards the justificatory grounds for servitus on the basis of potentia and the normative force of covenanting which engenders dominium and servitus, as in the case of a conquered servant who agrees to become a subject in the face of the power of a dominus. He is emphatic that all human beings are equal in the state of nature and any argument otherwise, through any appeal to intrinsic natures, merit, or differences in rationality, is simply a product of pride.

Against Hobbes, Leibniz argues on the basis of his commitment to the idea of rational souls and their perfectibility that a person can merit becoming a slave due to their inability to govern themselves. In turn, a master can merit their position in virtue of their wisdom. This commitment to rational souls motivated Leibniz’s criticisms of Hobbes’s account of absolute dominion, since Leibniz drove his argument by appealing to the rational soul as grounds for self-ownership. Yet, as we will see, these same commitments led Leibniz down a different path and into an intellectual tradition that began with Aristotle’s justification of enslavement, a tradition distinct from Hobbes and his neo-Roman sensibilities.

Leibniz writes towards the end of an incomplete manuscript: “In accordance with the nature of things, no person should be the slave of another, unless he merits to be a slave, that is to say, he is incapable of conducting himself well.”79 This notion of meriting enslavement does not contradict his claim that servitus in the sense of ownership of a person is impermissible but is a new kind of claim. We can begin to make sense of it by observing the following distinction regarding rationality: (a) one can give a description of a person’s rational nature as a metaphysical fact in accordance with the nature of things; (b) then one can acknowledge the person’s normative actualization of rationality in terms of self-governance. Human beings are imperfect since we are not pure “rational substances,” but occupy “a double status or position” as both physical and rational.80 We often fail to actualize our rational natures. The same thing can be said about freedom for Leibniz, since all intelligent substances have a capacity for freedom in their natures as they are made in the image of God. Still, human agents need to actualize their rational spontaneity to be truly free.81 It is in this latter normative register that Leibniz intends his claim about meriting to be a slave, for distributive justice demands that persons be distinguished according “to merit and to lack of merit [demerite].”82

So, within this 1703 manuscript, Leibniz takes himself to be following Aristotle in arguing that “natural right” is that which “is most conducive to order.”83 His line of reasoning echoes a statement he wrote a few years earlier in a letter to Thomas Burnett of Kemney dated to February 1700. Leibniz says that, out of all the things he could say about John Locke’s Two Treatises of Government (1689), he wants to report his thoughts on the supposed natural equality of human beings: “This equality would be certain if it were the case that all men had the same advantages, but this is not the case, so it seems that Aristotle was more right on this matter than Hobbes.”84 He goes on to draw an analogy from Aristotle that if persons found themselves at sea on a ship, “it would not conform to reason nor to nature, that those who understand nothing of travelling at sea, would allege to be pilots.”85 The most skilled at seafaring merit the task of piloting a ship. Thus, in line with Leibniz’s own convictions and his interpretation of Aristotle: “following natural reason the government belongs to the wisest.”86 As a consequence, Leibniz argues that the normative demands of reason and distributive justice entail that persons ought to be distinguished according to their differing advantages.

Distributive justice requires a kind of legitimate inequality that serves the common good. Leibniz has in mind the mathematical correlate as geometric proportionality. Those who contribute the most to the social good deserve the most – hence the precept ‘to give to each what they are due.’ In the same letter to Kemney, Leibniz writes, “the imperfection of human nature means that we do not want to listen to reason, which has forced the wisest to employ force and skill to establish some tolerable order.”87 He thus ties together the right to govern with the normative quality of rational merit, i.e., wisdom.

On the basis of such insight, Leibniz adopts the doctrine of Aristotelian natural slavery within his political theory. “Aristotle,” he writes in the Theodicy, “used to say that man is in a natural servitude [natura servus] who cannot conduct himself and stands in need of being governed.”88 A parallel assertion appears a couple of years later in a letter to Friedrich Wilhelm Bierling dated to 20 October 1712. Leibniz responds to a distinction that Bierling draws between the wise and the unwise (insipentes), writing:

I approve of the distinction between the unwise and various degrees of those who make progress in wisdom. I concede that the unwise must be forced by some authority [cogi debere imperio]; and this is what Aristotle meant when he said that some are slaves by nature [naturae servos]. I add that the less wisdom someone has, the more need he has of being forced by an authority.89

Thus, Leibniz’s defense of natural slavery is that some persons are so unwise that they deserve to be a slave since they cannot sufficiently self-determine themselves rationally. These persons cannot govern themselves in that they do not realize what is their own proper end along with what is conducive to the common good. Hence, not only do such persons merit to be slaves, but sometimes the wise – who do in fact rationally discern the proper ends of themselves, others, and hence the common good – must use force and skill in governing them.

Leibnizian natural slavery is paternalistic: a slave-master is bound “to advance his slave’s [Knechts] freedom through education, at least as far as this is necessary for the happiness of the slave.”90 If there are persons who normatively merit to be a slave, then there also are those who merit to be a master in terms of rational governance. Leibniz thus argues that, in the case of a legitimate relation of master and slave, there are benefits for both parties, since “the same virtues” are not necessary in all the same conditions “to make a man happy.”91 That is, some persons are better off in terms of their happiness to receive governance from another agent who is wiser.

Thus, just as Hobbes uptakes and transforms the Roman justification of slavery, Leibniz draws on Aristotle but makes himself distinct. It would be too far outside the scope of this article to interpret what Aristotle meant by natural slavery, so a summary by Joseph Karbowski will suffice: “a human being who is by nature suited to be a piece of property that belongs to someone else and functions as a second-order tool for action.”92 As has been observed by several scholars, Aristotle’s account of natural slavery is not paternalistic93 because he describes the slave as wholly the master’s and as secondary to the ends of the master. “A slave,” Aristotle said, “is not just his master’s slave, but wholly his.”94

Leibniz’s paternalistic position is idiosyncratic in at least two ways. First his conception of servitus does not say that a slave exists only for the sake of the master. As he writes in Divisio Societatum (1680): the relationship where the slave exists solely for the sake of the master “exists only between men and cattle.”95 Second, Leibniz combines a theory of natural slavery with his doctrine of rational souls, writing that “if souls were only mortal, this servitude might occur in entire races which are almost as dumb as cattle” but “souls are immortal and hence can sometime achieve understanding,” that is to say, rational souls are perfectible.96

“Natural servitude [Natürliche Knechtschafft] applies to unintelligent men insofar as it is not restricted by the rules of piety.”97 Leibniz argues that natural slavery is limited by the rules of piety that follow from universal justice – namely the ideas of rational souls as sole proprietors of their bodies, God’s dominium, and moral citizenship in the divine kingdom.

In sum, anti-Hobbes, Leibniz holds that rational, embodied persons cannot be absolutely possessed in either their person or their body. As we have seen, his position originates in substantially different commitments from Hobbes’s. In particular: Leibniz denies the equality of human beings with regard to the actualization of practical rationality or wisdom; he maintains a thick notion of personhood (i.e., each person is a rational substance); and he defends the perfectibility of rational persons. Leibniz prohibits chattel slavery but defends the possibility of paternalist slavery insofar as de jure slavery is restricted to usufructuary rights. His normative justification of servitus on the basis of rational merit would be unconditionally rejected by Hobbes.98 For a conquered servant is obligated to their master only insofar as power and security last. Furthermore, in virtue of the right to self-preservation, Hobbes states that the slave who has not covenanted with their master subsequently has “no obligation at all” and may “break their bonds” and “kill, or carry away captive their Master, justly.”99

5 Conclusion: Intellectual Legacies of Slavery and Race

What this dialectic has made manifest is how Hobbes’s position on slavery was interpreted and critiqued by Leibniz. Fundamentally, Hobbes and Leibniz diverge on the nature and grounds of slavery. How Hobbes and Leibniz respectively conceptualize legitimate authority, either as a monarch with irresistible power or with supreme wisdom, corresponds to how they disagree over the limits of de jure possession of another person and the justificatory grounds for enslavement. Hobbes emphasizes the role of potentia and consent whereas Leibniz privileges the role of practical rationality. At the heart of their disagreement, Leibniz’s encounter with Hobbesian slavery drove him to take the rational soul, or intelligent monad, as the ground for self-ownership in accordance with divine justice.

Hobbes took a radical stance in how he conceptualized servitus: a dominus has the absolute right to dispose of the personhood of conquered servants and captive slaves as de jure property. Leibniz further targeted Hobbes for maintaining the claim that slave-masters, in virtue of their de facto power, can possess slaves and their children such that their bodies are not their own, kill them for the least disobedience, and acquire rights to buy and sell them. This form of argument connecting slavery with property rights had a lasting aftermath. In 1769, the British abolitionist Granville Sharp would bring up De cive in the context of chattel slavery in Britain, as West-Indian slave-owners had argued that they could bring their black slaves to England without compromising their property rights over them.100

What Leibniz neglected to consider is how Hobbes distinguishes between conquered servants and captive slaves in terms of trust, along with the role of authorization in Leviathan. Hobbes’s justification of slavery is indebted to Roman jus gentium but his account still remains distinctive.

Leibniz defended natural slavery: some persons rationally merit governance by others, whereas the wise deserve the right to govern them. He justified this claim on the basis of his perfectionism and the demands of distributive justice. He attributed this justification to Aristotle while reinterpreting natural slavery as a paternalistic doctrine, i.e., a legitimate relation of master-slave that ought to benefit both parties. Moreover, possession of persons as immortal, rational souls can only extend as far as a de jure usufruct. Rational souls have sole proprietorship over their bodies due to the universal justice instituted by God.

Regarding the wider context of transatlantic slavery and the slave trade, Leibniz’s ideas countered the form of slavery defended by the Hobbesian position and jus gentium. But he never condemned the transatlantic slave trade as such. In 1786, Thomas Clarkson drove the appeal to self-ownership in virtue of the mind more forcefully against slave-trading than Leibniz ever did: “whenever you sell the liberty of a man, you have the power only of alluding to the body: the mind cannot be confined or bound.”101 So at best one can say that Leibniz foreshadows later gradualist positions that slavery should only be abolished over time,102 and not the immediatist position of Epifanio de Moirans’s 1682 assertion, “Everyone who owns some Blacks who are African slaves must set them free under pain of eternal damnation,”103 and of Quobna Ottobah Cugoano’s 1787 demand that black slaves acquired in transatlantic slavery ought to be emancipated immediately and that the British navy ought to be deployed to prevent any further oppression of Africans.104 Leibniz was either seemingly unfazed by or uninterested in the colonial conquests, genocide, and enslavement of indigenous peoples perpetuated by Europeans. One cannot claim ignorance on Leibniz’s part as, by 1689, he had read Bartolomé de las Casas’s Brevísima relación de la destrucción de las Indias (1552).105 So at worst, Leibniz’s paternalism and neo-Aristotelianism push him in the direction of Juan Ginés Sepúlveda’s colonialist justification of enslaving indigenous populations in the Americas on the ground that the indigenous display insita servitus or a kind of acquired natural slavery which could be transcended by conversion and enculturation to Christianity.106

The deeper aim of this article has been to contribute to something beyond its own scope: a historical reconstruction of the concept of slavery. The assumption has been that understanding slavery as a concept that was philosophically legitimatized will give us a better grasp on how slavery eventually became intertwined with race. For example, in the middle of the 18th century, the American Quaker John Woolman made observations on racial discrimination: “This is owing chiefly to the Idea of Slavery being connected with the Black Colour, and Liberty with the White.”107 In virtue of such a conceptual connection between slavery and race, it is crucial to take the concept of slavery as itself a part of the history of philosophy.


I thank the editors, Deborah Baumgold and Adrian Blau, and the anonymous reviewers for their criticism and feedback, especially the reviewer who suggested the current title of the article and pressed me on the issue of self-ownership. I give my thanks to Benjamin Randolph and John Christman for reading parts of the paper and to the participants of the tempo Conference 2021 where I first presented some of this material. Lastly, I am grateful to Robert Bernasconi for his substantive feedback and support.


Scholars have largely focused on two issues: (a) Leibniz’s critique of Hobbesian voluntarism; (b) Leibniz’s attempt to reconcile his Hobbesian commitment that agents can only be motivated to action by self-centered utility with the possibility of disinterested, pure love. See Gregory Brown, “Leibniz’s Moral Philosophy,” in The Continuum Companion to Leibniz, ed. by Brandon Look (London: Continuum, 2011): 223–238; Richard Arthur, Leibniz (Cambridge: Polity Press, 2014): 166–189; Christopher Johns, “The Grounds of Right and Obligation in Leibniz and Hobbes,” The Review of Metaphysics, 62, no. 3 (2009): 551–574; Ursula Goldenbaum, “All you need is love, love… Leibniz’s Vermittlung von Hobbes’ Naturrecht und christlicher Nächstenliebe als Grundlage seiner Definition der Gerechtigkeit,” in Neuzeitliches Denken: Festschrift Fur Hans Poser Zum 65. Geburtstag, ed. by Günter Abel, Hans-Jürgen Engfer, Christoph Hubig (Berlin: Walter de Gruyter, 2002): 209–31; Fiorenza Manzo, “How Sincere Was Leibniz’s Criticism of Hobbes’s Political Thought?,” The Leibniz Review, 30 (2020): 29–60.


Julia Jorati mentions the differences between Leibniz and Hobbes on the issue of slavery, but her focus is to reconstruct Leibniz’s argument against de jure chattel slavery. See “Leibniz on Slavery and the Ownership of Human Beings,” Journal of Modern Philosophy, 1, no. 10 (2019), 1–18.


The critical editions of these essays by Leibniz are to be found in: ‘Das Recht kann nicht ungerecht sein …’: Beiträge zu Leibniz’ Philosophie der Gerechtigkeit, ed. by Wenchao Li (Stuggart: Steiner, 2015).


Gottfried Wilhelm Leibniz, Sur la notion commune de la justice, in ‘Das Recht kann nicht ungerecht sein …’: 175–178; cf. Gottfried Wilhelm Leibniz, “Meditation on the Common Concept of Justice,” in Leibniz: Political Writings, ed. and trans. by Patrick Riley (Cambridge: Cambridge University Press, 1972): 61–63.


Hugo Grotius, The Rights of War and Peace, 3 volumes, ed. by Richard Tuck (Indianapolis: Liberty Fund, 2005): 508; 1360–2; Samuel von Pufendorf, De jure naturae et gentium (Londini Scanorum: Junghans, 1672): 838–9. See The Digest of Justinian, volume 1, ed. and trans. by Alan Watson (Philadelphia: University of Pennsylvania Press, 1985): 1.


See Max Radin, “Fundamental Concepts of the Roman Law,” California Law Review, 13, no. 3 (1925): 207–228.


Thomas Hobbes, On the Citizen, ed. by Richard Tuck and Michael Silverthorn, trans. by Michael Silverthorne (Cambridge: Cambridge University Press, 1998): 119.


Gottfried Wilhelm Leibniz, “Excerpts from the Letters to Thomas Burnett (1699–1712),” in Leibniz: Political Writings: 192.


Thomas Hobbes, Leviathan, ed. by Noel Malcom (Oxford: Clarendon Press, 2012): 1028.


Deborah Baumgold, “Slavery Discourse Before the Restoration: The Barbary Coast, Justinian’s Digest, and Hobbes’s Political Theory,” History of European Ideas, 36, no. 4 (2010): 417.


See Robert Filmer, Patriarcha and Other Political Works, ed. by Peter Laslett (Oxford: Basil Blackwell, 1949).


Leibniz, Sur la notion commune de la justice, 177; “Meditation on the Common Concept of Justice,” 63.


Justin Smith, Nature, Human Nature, and Human Difference: Race in Early Modern Philosophy (Princeton: Princeton University Press, 2015): 177–179.


Leibniz, Sur la notion commune de la justice, 169; “Meditation on the Common Concept of Justice,” 57.


Hobbes, Leviathan, 558.


Hobbes, Leviathan, 196.


A.P. Martinich, The Two Gods of Leviathan: Thomas Hobbes on Religion and Politics (Cambridge: Cambridge University Press, 1992): 76.


Hobbes, Leviathan, 230.


Hobbes, Leviathan, 558.


Gottfried Wilhelm Leibniz, Sur la nature de la bonté et de la justice, in ‘Das Recht kann nicht ungerecht sein …’: 154.


Gottfried Wilhelm Leibniz, Theodicy, ed. by Austin Farrer, trans. by E. M. Huggard (La Salle: Open Court Classics, 1985): § 130. References are to paragraphs.


Leibniz, Sur la notion commune de la justice, 174; “Meditation on the Common Concept of Justice,” 61.


Gottfried Wilhelm Leibniz, Codex Iuris Gentium (Praefatio) (1693), in Leibniz: Political Writings: 173.


Gottfried Wilhelm Leibniz, Opinion on the Principles of Pufendorf, in Leibniz: Political Writings: 72. See Gregory Brown, “Leibniz on the Ground of Moral Normativity and Obligation,” The Leibniz Review, 26 (2016): 11–62.


Leibniz, Sur la notion commune de la justice, 175; “Meditation on the Common Concept of Justice,” 62.


Leibniz, Sur la notion commune de la justice, 177; “Meditation on the Common Concept of Justice,” 63.


Daniel Lee, “Sovereignty and Dominium: The Foundations of Hobbesian Statehood,” in Hobbes’s On the Citizen: A Critical Guide, ed. by Robin Douglass and Johan Olsthoorn (Cambridge: Cambridge University Press, 2019): 134.


Thomas Hobbes, The Elements of Law, ed. by Ferdinand Tönnies, 2nd ed. (London: Frank Cass, 1969): 127.


Starting early in his intellectual career, Leibniz referenced many of Hobbes’s Latin works – from De corpore (1655), De homine (1658), De cive, to the Latin version of Leviathan. See Leibniz, “Schriftenverzeichnis zu vi.i und vi.ii,” in Sämtliche Schriften und Briefe, series 6, volume 2, ed. by Deutsche Akademie der Wissenschaften (Berlin: Akademie Verlag, 1966): 684.


Hobbes, On the Citizen, 104; cf. The Elements, 128–129.


Hobbes, On the Citizen, 104.


Hobbes, On the Citizen, 102; cf. Thomas Hobbes, De Cive: The Latin Version, ed. by Howard Warrender (Oxford: Clarendon Press, 1983): 160.


Hobbes, On the Citizen, 105; 108.


Laurens van Apeldoorn, “Property and Despotic Sovereignty,” in Hobbes’s On the Citizen, ed. Douglass and Olsthoorn: 123.


Hobbes, On the Citizen, 109.


Hobbes, On the Citizen, 104.


Unfortunately, due to limits in space, I cannot address whether Hobbes changes his position on the meaning of proprietorship across his works. See Arash Abizadeh, “Sovereign Jurisdiction, Territorial Rights, and Membership in Hobbes,” in The Oxford Handbook of Hobbes, ed. by Aloysius Martinich and Kinch Hoekstra (Oxford: Oxford University Press, 2013): 404; Laurens van Apeldoorn, “Hobbes on Property: Between Legal Certainty and Sovereign Discretion,” Hobbes Studies, 34, no. 1 (2021): 70.


Hobbes, Leviathan, 312.


Hobbes, Leviathan, 1028.


Hobbes, Leviathan, 1028.


Hobbes, Leviathan, 306.


Leibniz, Sur la notion commune de la justice, 169; “Meditation on the Common Concept of Justice,” 57.


Leibniz, Sur la notion commune de la justice, 175–176; “Meditation on the Common Concept of Justice,” 62.


Leibniz, Sur la notion commune de la justice, 176; cf. “Meditation on the Common Concept of Justice,” 62.


Leibniz, Sur la notion commune de la justice, 176; cf. “Meditation on the Common Concept of Justice,” 62.


Leibniz ascribes this account of just captivity to the Roman tradition in his Definitionum Juris Specimen (c. 1676): Gottfried Wilhelm Leibniz, Definitionum Juris Specimen, in Sämtliche Schriften und Briefe, series 6, volume 3, ed. by Deutsche Akademie der Wissenschaften (Berlin: Akademie Verlag, 1980): 606–609. See The Digest of Justinian, vol. 1: 15.


Hobbes, The Elements, 128.


Laurens van Apeldoorn, “Property and Despotic Sovereignty”: 116.


See James Jay Hamilton, “Hobbes’s Study and the Hardwick Library,” Journal of the History of Philosophy, 16, no. 4 (1978): 450.


Hugo Grotius, The Rights of War and Peace, Book iii: 1360–1362.


Grotius, The Rights of War and Peace, Book iii: 1360.


Hobbes, On the Citizen, 105; cf. The Elements, 130.


The Digest of Justinian, vol. 4: 1.


Gaius, Gaii Institutionum Iuris Civilis Commentarii Quattuor: Or Elements of Roman Law by Gaius, ed. by Edward Poste Edward and E. A. Whittuck (Oxford: Clarendon Press, 1904): 36.


Hobbes, The Elements, 128.


Hobbes, On the Citizen, 103; cf. The Elements, 128; De Cive, 160.


Hobbes, Leviathan, 314.


Johan Olsthoorn and Laurens van Apeldoorn argue that Hobbes’s position, as understood by Leibniz, was outside the mainstream in the period: “‘This man is my property’: Slavery and political absolutism in Locke and the classical social contract tradition,” European Journal of Political Theory, 21, no. 2 (2022): 270.


Gottfried Wilhelm Leibniz, Elementa Juris Naturalis, in Sämtliche Schriften und Briefe, series 6, volume 1, ed. by Deutsche Akademie der Wissenschaften (Berlin: Akademie Verlag, 1971): 432.


Leibniz, Codex Iuris Gentium, 173.


Gottfried Wilhelm Leibniz, “Discourse on Metaphysics,” in Philosophical Essays, ed. and trans. by Roger Ariew and Daniel Garber (Indianapolis: Hackett Publishing Company, 1989): 66.


Leibniz, Sur la notion commune de la justice, 176–177; cf. “Meditation on the Common Concept of Justice,” 62.


Leibniz, Sur la notion commune de la justice, 177; cf. “Meditation on the Common Concept of Justice,” 62.


Cf. Jorati, “Leibniz on Slavery,” 10n47.


Leibniz, Sur la notion commune de la justice, 177; “Meditation on the Common Concept of Justice,” 62.


Leibniz, Sur la notion commune de la justice, 177; “Meditation on the Common Concept of Justice,” 62.


Leibniz, Codex Iuris Gentium, 174. Leibniz claims that we are prohibited from abusing our bodies since we owe ourselves and everything to God.


Gottfried Wilhelm Leibniz, New Essays on Human Understanding, ed. by Peter Remnant and Jonathan Bennett (Cambridge: Cambridge University Press, 1996): 201. Pagination is from Sämtliche Schriften und Briefe, series 6, volume 6.


Leibniz, Sur la notion commune de la justice, 177; “Meditation on the Common Concept of Justice,” 62.


Leibniz, Sur la notion commune de la justice, 177; cf. “Meditation on the Common Concept of Justice,” 63.


Leibniz, Sur la notion commune de la justice, 177; cf. “Meditation on the Common Concept of Justice,” 63.


See Jorati, “Leibniz on Slavery,” 9n44.


Leibniz, Sur la notion commune de la justice, 177; cf. “Meditation on the Common Concept of Justice,” 62–63.


The Digest of Justinian, vol. 1: 216.


Leibniz, Sur la notion commune de la justice, 177; cf. “Meditation on the Common Concept of Justice,” 63.


Gottfried Wilhelm Leibniz, “On the Radical Origination of Things,” in Philosophical Papers and Letters, 2nd edition, ed. and trans. by Leroy Loemker (Dordrect: Kluwer Academic Publishers, 1989): 490–491.


See Smith, Nature, Human Nature, and Human Difference, 170–174; Daniel Cook, “Leibniz on ‘Advancing toward Greater Culture’,” Studia Leibnitiana, 50, no. 2 (2018): 163–179; John Harfouch, “Does Leibniz Have Any Place in a History of Racism?,” Philosophy Today, 61, no. 3 (2017): 737–55; and Peter Fenves, “Imagining and Inundation of Australians; or, Leibniz on the Principles of Grace and Race,” in Race and Modern Philosophy, ed. by Andrew Valls (Ithaca: Cornell University Press, 2005): 88–96.


Hobbes, Leviathan, 234; cf. Hobbes, On the Citizen, 49–50.


Leibniz, Sur la notion commune de la justice, 178; cf. “Meditation on the Common Concept of Justice,” 63.


Gottfried Wilhelm Leibniz, “Leibniz: Unpublished Comments on Bayle’s Note H,” in Leibniz’s ‘New System’ and Associated Contemporary Texts, ed. and trans. by R.S. Woolhouse and Richard Francks (Oxford: Clarendon Press, 1997): 75.


See Julia Jorati, Leibniz on Causation and Agency (Cambridge: Cambridge University Press, 2017): 53n46.


Leibniz, Sur la notion commune de la justice, 168; “Meditation on the Common Concept of Justice,” 56.


Leibniz, Sur la notion commune de la justice, 178; “Meditation on the Common Concept of Justice,” 63.


Gottfried Wilhelm Leibniz, “Excerpts from Three Letters to Thomas Burnett (1699–1712),” in Leibniz: Political Writings: 192.


Leibniz, “Excerpts from Three Letters”: 192.


Leibniz, “Excerpts from Three Letters”: 192.


Leibniz, “Excerpts from Three Letters”: 192.


Leibniz, Theodicy: §228.


Gottfried Wilhelm Leibniz, “Leibniz an Bierling,” Die Philosophischen Schriften von Gottfried Wilhelm Leibniz, volume 7, ed. by C.I. Gerhardt (Berlin, reprint. Hildesheim: Olms, 1890): 508.


Leibniz, “On Natural Law,” in Philosophical Papers and Letters, 2nd edition: 428.


Leibniz, Sur la notion commune de la justice, 178; “Meditation on the Common Concept of Justice,” 63.


Joseph A. Karbowski, “Aristotle’s Scientific Inquiry into Natural Slavery,” Journal of the History of Philosophy, 51, no. 3 (2013): 339–340.


Thornton Lockwood, “Is Natural Slavery Beneficial?,” Journal of the History of Philosophy, 45, no. 2 (2007): 215; Richard Kraut, Aristotle: Political Philosophy (New York: Oxford University Press, 2002): 299, 299n42.


Aristotle, Politics: A New Translation, ed. and trans. by C.D.C Reeve (Indiana: Hackett Publishing Company, Inc., 2017): 6.


Leibniz, “On Natural Law,” in Philosophical Papers and Letters, 2nd edition: 428.


Leibniz, “On Natural Law”: 428–429.


Leibniz, “On Natural Law”: 429.


I speculate that if there is any place for the natural right over another person in Hobbes’s philosophy, it is not in virtue of rationality as in the case of Leibniz but, as Kinch Hoekstra argues, it is because for Hobbes: “Rulers do arise naturally, but nonetheless must be consented to; and their power itself can generally be a sufficient sign of consent.” This interpretation is clearest in the case of God’s irresistible power, but I cannot defend the full import of this claim within the article (“The de facto Turn in Hobbes’s Political Philosophy,” in Leviathan after 350 Years, ed. by Tom Sorell and Luc Foisneau [Oxford: Clarendon Press, 2004]: 72n188).


Hobbes, Leviathan, 312.


Granville Sharp, A Representation of the Injustice and Dangerous Tendency of Tolerating Slavery; or of Admitting the Least Claim of Private Property in the Persons of Men, in England (London: Printed for Benjamin White and Robert Horsfield, 1769): 12.


Thomas Clarkson, An Essay on the Slavery and Commerce of the Human Species (London: J. Phillips, 1786): 70.


See William Paley, The Principles of Moral and Political Philosophy, volume 1 (Boston: N. H Whitaker, 1832): 152.


Epifanio de Moirans, A Just Defense of the Natural Freedom of Slaves: All Slaves Should be Free: A Critical Edition and Translation of Servi liberi seu naturalis mancipiorum libertatis iusta defensio, ed. and trans. by E. R. Sunshine (Lewiston: Mellen, 2007): 109.


Quobna Ottobah Cugoano, Thoughts and Sentiments on the Evil of Slavery, ed. by Vincent Caretta (New York, Penguin Books, 1999): 98–101.


Gottfried Wilhelm Leibniz, “Leibniz für Theodor Althet Heinrich von Strattman. Entwurf einer Blibliotheca universalis selecta,” Sämtliche schriften und briefe, series 1, volume 5, ed. by Deutsche Akademie der Wissenschaften (Berlin: Akademie Verlag, 1970): 455.


Juan Ginés Sepúlveda, “Democrates Alter de J. G. de Sepúlveda,” ed. by Marcelino Menéndez y Pelayo., in Boletín de la Real Academia de la Historia, volume 21 (Madrid: Real Academia de la Historia, 1892): 312. See Daniel Cook, “Leibniz on ‘Advancing toward Greater Culture,’” 175–178.


John Woolman, Considerations on Keeping Negroes; Recommended to the Professors of Christianity, of Every Denomination. Part Second (Philadelphia: Printed by B. Franklin, and D. Hall., 1762): 29.

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