David Hume and the Politics of Slavery

Slavery in Hume’s Early Work

Before publishing a word of political philosophy, Hume briefly entertained the possibility of becoming a merchant. This took him to London and then on to “a considerable Trader in Bristol” for several months in 1734, at a time when the city was at the center of the international slave and sugar markets (Hume, 1932b: 1:18; see Rothschild, 2009). None of Hume’s published work addresses his mercantile experience directly. Nor does Hume elaborate as to why he quickly found the “scene” in Bristol “totally unsuitable” (1932a: 1:1–2). But Hume may have been thinking of Bristol or London when he explained in the Treatise that long distances in time have a more considerable effect on the imagination than long distances in space. He offered a telling example: “[E]ven the greatest distance of place this globe can admit” will not necessarily disrupt the mind’s capacity to find contiguity between persons or objects. Commerce has a way of bridging our ideas of distance, which is why “a West-India merchant will tell you, that he is not without concern about what passes in Jamaica.”² Hume directly broached the subject of slavery in several short passages in books 2 and 3 of the Treatise, each of which addresses expectations about property.

Some scholars argue that the tight connection Hume makes between the origin of justice and the origin of property renders slavery incompatible with his political philosophy (Moore, 1976: 111; Stewart, 1992: 186–187). Where Aristotle (1998: 7–11) held that it was not unjust to enslave human beings who are slaves “by nature,” Hume claimed that justice itself is the product of human convention, “not deriv’d from nature, but from artifice” (Treatise, III.ii.2.9: 489). Relationships in economic society are “artificial” because people coordinate out of self-interest, not instinctive benevolence, although Hume emphasized that we subsequently cultivate a moral sympathy for the public interest that the rules of justice produce and protect. One implication of this self-interested origin of justice is that, on balance, “every individual person must find himself a gainer” when cooperating with the shared convention of respecting each other’s property. Even where particular acts of justice seem to contradict our private interests, Hume supposes that members of society will converge on the judgment that it is in their mutual long-term interest to leave others in possession of their goods, provided that others behave the same way in return (Treatise, III.ii.2.22–24: 497–500). From this, James Moore extrapolates that “the institution of slavery is incompatible with the central assumption” of Hume’s theory of a just society, namely, “that every member of it is entitled to consideration as an owner of property.” Moore (1976: 111) observes that Hume’s attention to the standpoint of every individual distinguishes his theory from classical utilitarianism. Hume’s emphasis on “general rules” that apply to each person looks more like John Rawls’s conception of procedural fairness. Even if the overall utility of slavery somehow outweighed the suffering of the slaves, slavery would still violate Hume’s expectation that every person be treated according to the same equal procedure (Moore, 1976: 111; Rawls, 1958: 188–189).

Hume’s reference to “the work of our slaves” complicates this conclusion (Treatise, III.ii.3.10: 509). In the course of outlining the most considerable rules that determine stable property possession, Hume mentions the institution of slavery—without denouncing it. Hume specifies that property by the rule of “accession” occurs when the imagination makes an easy association between an object already in someone’s possession and another object closely connected with it:

Thus the fruits of our garden, the offspring of our cattle, and the work of our slaves, are all of them esteem’d our property, even before possession. Where objects are connected together in the imagination, they are apt to be put on the same footing, and are commonly suppos’d to be endow’d with the same qualities (Treatise, III.ii.3.10: 509).

The example implies that slaves are “objects” whose work belongs to their masters, not property owners with a claim to procedural equality. John B. Stewart (1992: 187) wonders if this passage might be excused as “a thoughtless carryover” from Hume’s studies in Roman law. The “acquisition of fruits” in Roman property law describes cases in which the owner of a principal object also acquires the fruits of that object, which for the Romans included the earnings of the owner’s slave (Domingo, 2018: 150–151; The Digest of Justinian, 1998: 22.1.25: 181). Yet Glen Doris (2011: 41–42) objects that Hume’s casual reference to “the work of our slaves” makes it hard to justify Stewart’s confidence that slavery is alien to Hume’s idea of civil society. Hume fails to clarify whether the general rules he associates with stable property possession would protect slaveholders in societies where slaves are already regarded as a form of property, and the Treatise contains no definitive statement that slavery is morally wrong. When Hume briefly returned to the subject of property “accession” in An Enquiry Concerning the Principles of Morals, he dropped the allusion to slaveholding, leaving the question unresolved (Hume, 1998: 100, note 65).

The second Enquiry does, however, introduce a puzzling thought experiment that touches on the relationship between slavery and justice. After reiterating that the rules of justice arise from mutual social conventions, Hume asks us to imagine:

a species of creatures, intermingled with men, which, though rational, were possessed of such inferior strength, both of body and mind, that they were incapable of all resistance, and could never, upon the highest provocation, make us feel the effects of their resentment (1998: 18).

Hume argues that such disparities in strength and rationality would make it impossible for these hypothetical creatures to enter into our shared society. In what seems to be a sketch of Aristotle’s view of natural slavery, Hume observes that our relationship with such creatures would entail “absolute command on one side, and servile obedience on the other.” We would owe them kindness and compassion, but not, properly speaking, common justice (Hume, 1998: 18; see Schabas and Wennerlind, 2021: 193). Hume then clarifies that this example “plainly” illustrates human beings’ relationship with animals. He appears to be arguing that animals do not pose a sufficient “inconvenience” to the social order to warrant inclusion in the restraints of justice (Hume, 1998: 18; see Pollock, 2016).

The passage becomes more controversial when Hume asks whether his thought experiment extends to native Americans and women:

The great superiority of civilized Europeans above barbarous Indians, tempted us to imagine ourselves on the same footing with regard to them [i.e. the inferior species of creature], and made us throw off all restraints of justice, and even of humanity, in our treatment of them. In many nations, the female sex are reduced to like slavery, and are rendered incapable of all property, in opposition to their lordly masters. But though the males, when united, have, in all countries, bodily force sufficient to maintain this severe tyranny; yet such are the insinuation, address, and charms of their fair companions, that women are commonly able to break the confederacy, and share with the other sex in all the rights and privileges of society (1998: 18).

Is Hume asserting that groups who lack sufficient coercive power also lack the requisite capacity to participate in just society (see Barry, 1989: 160–163; Reid, 1788: 437–438)? His reference to what the colonizers are “tempted” to imagine counsels against this interpretation (Kuflik, 1998: 570; Taylor, 2015: 176–177; Cf. Ridge, 2010). The unjust treatment of the Amerindians reveals more about European self-interest than the capacity of the natives to make their resentment felt. The fact that women, who resemble the natives in the “slavery” they experience vis-à-vis European men, deploy strategies for overcoming this subjugation seems to confirm that even groups without coercive power understand the basis of justice and are prepared to demand their rights. Hume assumes that human beings interacting with the hypothetical creatures in his thought experiment would still be bound by the “laws of humanity,” if not justice. So it is notable that he accuses European men of abandoning not just justice but even “humanity.” As we will see below, this is the same language Hume uses to denounce slavery in the American colonies. Slaveholding turns the master into a “petty tyrant” who displays “little humanity” toward his “fellow creatures” and who “trample[s] upon human nature” (“Populousness” in Hume, 2021: 282). Although the passage from the second Enquiry still leaves Hume open to charges of paternalism and sexism (Nussbaum, 2006: 48–49; Roberts, 2020), it is consistent with his overall rejection of slavery (Sebastiani, 2013: 37, 122).

Hume has the most to say about the psychological effects of slaveholding in book 2 of the Treatise, where he anticipates Adam Smith’s worry that the “love of dominion and authority” would make slavery difficult to eliminate from the many areas of the globe where it still persisted (Smith, 1982: 187, 192). In the section titled “Of Property and Riches,” Hume explores the close connection between property, pride, and our relations with others (Treatise, II.i.10: 309–316). He explains that an item of property—say, a beautiful house—will naturally carry our thought to the idea of the item’s owner. For the owner of the house, the thought of his property causes a reflexive association with his idea of himself, stimulating the passion of pride. Hume emphasizes that much of the pride we take in property has to do with the pleasure we anticipate satisfying. Riches are desirable because they afford the social power of acquiring what pleases:

For the same reason, that riches cause pleasure and pride, and poverty excites uneasiness and humility, power must produce the former emotions, and slavery the latter. Power or an authority over others makes us capable of satisfying all our desires; as slavery, by subjecting us to the will of others, exposes us to a thousand wants, and mortifications (Treatise, II.i.10.11: 315).

The passage resonates with Hobbes’s (1994: 50–54) psychology of power and dominion. Property is entangled in the self’s desire for recognition, and in a world of scarce resources and attention, some people accrue more power than others. Those with property can exert authority, while those without it experience a feeling of slavery (Merrill, 2015: 72–73).

Hume defines property in this section as a relation between a person and an object that permits him the exclusive use of that object, “without violating the laws of justice and moral equity” (Treatise, II.i.10.1: 309). This would seem to disallow any justification for holding other people as property. Yet Hume is here interested in examining how the master–slave relationship illustrates both the pride he associates with property-ownership in objects and the comparative nature of human power:

’Tis here worth observing, that the vanity of power, or shame of slavery, are much augmented by the consideration of the persons, over whom we exercise our authority, or who exercise it over us. For supposing it possible to frame statues of such an admirable mechanism, that they cou’d move and act in obedience to the will; ’tis evident the possession of them wou’d give pleasure and pride, but not to such a degree, as the same authority, when exerted over sensible and rational creatures, whose condition, being compar’d to our own, makes it seem more agreeable and honourable. Comparison is in every case a sure method of augmenting our esteem of any thing (Treatise, II.i.10.12: 315–316).

The prideful master craves an attentive audience. Even if an automaton could perform the same tasks as human beings, Hume suspects that masters would still prefer to exercise authority over other “sensible and rational” humans because the slave serves as a captive, conscious witness to the master’s relative power.

The master–slave relationship serves as a case study for what Hume will call the “principle of comparison.” Comparison is quite similar to the process of sympathy, except it inverts the affective tendencies we find sympathetic in others. Sympathy for Hume is a causal mechanism that enlivens our idea of someone else’s passions, whereby we come to share in the same impression we suppose the other person is feeling. Comparison causes “a reverst sensation.” It occurs when sympathizing with someone else’s unhappy emotions intensifies our consciousness of our own, comparatively happy, position (Treatise, II.ii.8.9–12: 375–377; see Postema, 2005). The master–slave comparison reappears in Hume’s section on reflexive passions like malice and envy, where he observes that “the great feel a double pleasure in authority from the comparison of their own condition with that of their slaves” (Treatise, II.ii.8.14: 378). The master’s idea of the slave directs him back to a positive idea of his own self, prompting a feeling of pride that is further magnified when the master contrasts his own pleasure against his sense of the slave’s misery. Notice that the slave in this comparison differs from the hypothetical creatures Hume introduces in the second Enquiry. Nowhere in the Treatise does Hume suggest that slaves cannot “make us feel the effects of their resentment.” Rather, the master perceives slavery to be shameful and difficult precisely because he regards the slave as a “sensible and rational creature,” who thinks and feels much as he does (Treatise, II.i.10.12: 315–316; cf. Hume, 1998: 18). If slavery were not so shameful, the pleasures of power would be less intense.

Adam Smith would describe a similar psychology in the Wealth of Nations. Smith denounced slavery as ethically wrong and economically backward, yet he shared Hume’s insight that slavery is closely associated with the desire for relative power over other human beings. “The pride of man makes him love to domineer, and nothing mortifies him so much as to be obligated to condescend to persuade his inferiors.” Smith (1981: 388) assumed that “wherever the law allows it, and the nature of the work can afford it,” people will “generally prefer the service of slaves to that of freemen” (see Sagar, 2022: 60–67). In fact, Smith feared that slavery was bound to be more oppressive in republics, where citizens define their status as freemen over and against those they enslave. Smith (1982: 182) remarked in his Lectures on Jurisprudence (c. 1762), which draw liberally from Hume, that the “freedom of the free was the cause of the great oppression of the slaves” in ancient Rome. The Roman concept of freedom had the potential to exacerbate the pride human beings take in comparing their social status to others.

Hume began to chart his alternative approach to “civil liberty” in the Essays, Political and Moral (1741–1742), where he challenged the popular Whig distinction between English liberty and Gallic “slavery” (Forbes, 1975). Hume informed readers that personal liberty was possible in either “free governments” or monarchies, provided that the “civilized” monarch respects subjects’ property and the rule of law (“Civil Liberty” in Hume, 2021: 89–91). He was ready to concede that governments that fail “to exempt one man from the dominion of another” expose their subjects to “oppression and slavery.” Indeed, people who live within the “small compass” of a lawless ruler “are slaves in the full and proper sense of the word” (“Rise and Progress” in Hume, 2021: 104–105). But Hume was less concerned with the difference between modern republics and monarchies than with the difference between commercial and precommercial regimes. Precommercial societies were populated by “unhappy slaves” because the majority of subjects had no means for securing independent property (“Rise and Progress,” 2021: 109, also 104–105). Such societies were “barbarous” because they lacked arts and manufactures, the sources of economic development that Hume routinely presents as the historical solution to ancient slavery and medieval feudalism (“Of Refinement in the Arts” in Hume, 2021: 213–215, 1983: 2:522–524, 3:74–82, 4:383–385). The priority Hume placed on commercial exchange made him impatient with neo-Roman Whigs who compared modern European monarchies to tyrannies. Such rhetoric ignored the fact that Europe’s “civilized” monarchies now emulated republican regimes in their respect for private property and lawful administration. Any “dependence” citizens still had on their sovereign was “scarcely felt” because the monarch was “so far removed from them” and had little incentive to disrupt his state’s economic security (“Rise and Progress” in Hume, 2021: 110).

Hume continued to develop this defense of commercial states in the Political Discourses of 1752, a collection of essays whose title invites a comparison with Machiavelli’s Discorsi and James Harrington’s Political Discourses. Hume signaled that he, too, was seeking the first principles of good government (“Idea of a Perfect Commonwealth” in Hume, 2021: 363–364; Rothschild, 2009: 413). But unlike Machiavelli and Harrington, Hume harbored little affection for pre-commercial republicanism. He regarded Rome as an “ill modelled government”, whose massive armies diverted citizen labor away from more productive trade and manufactures (“Of Commerce” in Hume, 2021: 214). Over a third of the pages in the Political Discourses are dedicated to “Populousness of Ancient Nations,” a detailed demographic enquiry into ancient and modern standards of living. It is here that Hume articulated his most direct challenge to the Roman conception of liberty.

“Populousness of Ancient Nations” and Slavery

The main purpose of the essay was to cast doubt on the popular thesis—advanced by contemporaries like Montesquieu and Robert Wallace—that modern Europe’s population had declined since ancient times (see Tomaselli, 1988; Whelan, 1991). The question of “comparative populousness” was another way of framing the classic ancient-modern debate. All things being equal, Hume presumed that a larger population was a sign of greater social prosperity and political security. He treated slavery as his key historical variable:

The chief difference between the domestic œconomy of the ancients and that of the moderns consists in the practice of slavery, which prevailed among the former, and which has been abolished for some centuries throughout the greater part of Europe (Hume, 2021: 281–282).

If Hume could show that a slave economy hindered population growth, he could also infer that modern Europe—where slavery had largely been abolished—was home to preferable social and political institutions.

The project is in explicit dialogue with Montesquieu’s Spirit of the Laws (See Hume, 1932b: 1:140, 2021: 280, 329). ³ Montesquieu not only examined the multiplicity of factors shaping ancient and modern constitutions but also issued one of the most important Enlightenment critiques of slaveholding, in which he took specific issue with the Roman jurists who held that slavery could be made compatible with civil right (1989: 247–248). The problem with Montesquieu is that he continued to assume that modern European governments suffered depopulation and he referred to slavery as one reason for greater populousness in antiquity (1989: 427–56, 2008: 149, 154). Hume’s answer to this assumption was twofold. His essay is at once a painstaking exercise in political arithmetic and a polemic against ancient manners and constitutions (Baumstark, 2007: 76–84; Box and Silverthorne, 2013: 227).

Hume began by emphasizing the barbarity of ancient slavery: The Romans exposed sick and elderly slaves to starvation, cultivated the land using chain-gangs, hosted “inhuman sports” in their amphitheaters, and relied on civil and criminal testimony from tortured slaves (Hume, 2021: 282–283). It is here, in the opening polemic, that Hume distinguished his approach from “the passionate admirers of the ancients” and “the zealous partizans of civil liberty.” Hume (2021: 282) complained that such authors refer to modern monarchy “with the harsh denomination of slavery,” even as they “cannot forbear regretting the loss of this institution [i.e. ancient slavery].” His allusion is almost certainly to the republican patriot Andrew Fletcher. In his Two Discourses Concerning the State of Scotland, Fletcher likened Scottish dependence on the British monarchy to a form of political slavery, even as he proceeded to recommend a series of agrarian reforms that would place Scotland’s vagrants in forced servitude.

Fletcher attributed the widespread poverty he witnessed in 1690s Scotland to the disappearance of the master-servant relationship that structured pre-Christian antiquity (Fletcher, 1997: 57–58; see Robertson, 1983: 142–144). Fletcher believed vagrancy had been rare among “the wise antients” because masters treated their slaves as a public resource. “Every man [was] useful to the commonwealth,” with slaves supplying the labor force for grand highways, aqueducts, amphitheaters, and monuments (1997: 58, 64). Writing after a series of famines devastated the Scottish countryside, Fletcher held that modern workhouses were insufficient for alleviating economic crisis. The poor in ancient times had received basic food, clothing, and lodging for their families precisely because they were regarded as “the possession of another” (1997: 60). ⁴ Fletcher therefore proposed that Scottish estate-holders be obliged to take in a proportional number of “vagabonds” as forced domestic servants. He predicted that “such enemies of all work and labour” would at first resist his program out of pride, “esteeming their own condition above that which they will be sure to call slavery” (1997: 68–69). Yet Fletcher emphasized that masters must offer their servants food and shelter, maintain servants’ families, and provide for a basic education and religious instruction. While these “servants” would not possess property and could be sold “without their consent” (1997: 62–63), Fletcher insisted that his proposal differed from political slavery because masters would not possess power over their servant’s lives. “A slave,” he clarified:

properly is one, who is absolutely subjected to the will of another man without remedy: and not one that is only subjected under certain limitations, and upon certain accounts necessary for the commonwealth, though such may go under that name (1997: 61).

Beyond his duties within the household, a servant would be subject only to the political laws of the commonwealth, “not to the will of his master.” Servants would therefore remain “free” in the neo-Roman sense (Fletcher, 1997: 61–63). ⁵ By the logic of Fletcher’s idiosyncratic proposal, indefinite servitude was permissible—and indeed economically advantageous—so long as it existed in a government in which no one was a “slave” to the arbitrary will of a “tyrant” (Fletcher, 1997: 63; but see Lista, 2018: 181–185).

Hume was quick to note that this definition of political liberty still left Fletcher’s “servants” at the mercy of their masters’ arbitrary rule. He opened his discourse on population by observing:

[H]uman nature, in general, really enjoys more liberty at present, in the most arbitrary government of Europe, than it ever did during the most flourishing period of ancient times. As much as submission to a petty prince, whose dominions extend not beyond a single city, is more grievous than obedience to a great monarch; so much is domestic slavery more cruel and oppressive than any civil subjection whatsoever. The more the master is removed from us in place and rank, the greater liberty we enjoy; the less are our actions inspected and controuled; and the fainter that cruel comparison between our own subjection, and the freedom, and even dominion of another (Hume, 2021: 282).

Hume reversed Fletcher’s priorities and asserted that personal slavery is more oppressive than civil slavery because domestic masters have greater opportunity to interfere in their subjects’ daily lives. Hume had argued in the Treatise that human beings’ tendency to measure their own pleasure against others’ affliction is most intense where social “proximity” and “resemblance” make it easy for the mind to move from one impression to another, in keeping with the precept that objects appear larger or smaller in comparison with others (Treatise, II.ii.8.7, II.ii.8.11–13: 375–378). This “principle of comparison” reappears in “Populousness” to account for “that cruel comparison” between freedom and subjection in the domestic sphere. Hume was less concerned with the political tyranny of a faraway prince because distance in space and social rank disrupts the mind’s association of ideas. But personal slavery entails proximity, turning every master into “a petty tyrant . . . educated amidst the flattery, submission, and low debasement of his slaves.” As far as Hume (2021: 282) was concerned, Fletcher’s program for domestic servitude was indistinguishable from “real slavery and subjection.”

John Robertson notes in the Cambridge edition of Fletcher’s Political Works that Fletcher’s “draconian” proposal was “not taken too seriously by contemporaries” in the 1690s (Fletcher, 1997: 70n33). Margaret Watkins (2013: 110) takes this to mean that Hume’s quarrel with Fletcher was mainly pedantic, since Fletcher’s proposal was by then “an old one” and had “largely fallen on deaf ears.” However, it is worth noting that Fletcher’s collected Works were not published until 1732. They were reprinted in 1737 and then again in 1749, just as Hume was drafting his Political Discourses. ⁶ Fletcher’s writings served as a common point of reference in Scottish debates over slavery’s future. Francis Hutcheson, for instance, repeated a version of Fletcher’s proposal when he asserted that “perpetual slavery” was an effectual punishment for “idle vagrants.” Hutcheson (1755: 2: 202–203) firmly rejected Aristotle’s doctrine of natural slavery, but he agreed in his posthumous treatise A System of Moral Philosophy that slavery might be an appropriate solution for those who consistently failed to support themselves or their families through their own labor (see Rozbicki, 2001: 35–38). Fletcher was also a source for pro-slavery advocates in two landmark cases on the status of slaveholding in Scotland, Sheddan v. Montgomery (1756) and Knight v. Wedderburn (1773–1778). The counsel for Robert Sheddan—a merchant who sought to prevent his baptized black slave from fleeing Edinburgh—told the Court of Session that Fletcher held slavery “not inconsistent with the rights of a free government” (cited in Whyte, 2006: 30). Two decades later, the advocate for the slaveholder John Wedderburn placed Fletcher in the company of Plato, Cicero, and Thomas More—philosophers who all “considered the institution of slavery as a proper ingredient in a perfect government” (cited in Whyte, 2006: 30). As late as the 1790s, Dugald Stewart felt compelled to explain why Fletcher’s solution to poverty was misguided. Stewart (1855: 211) told his students at the University of Edinburgh that Fletcher was a thinker whose predilection for the classics led him to reverse the natural progress of political economy in favor of “the violent and cruel laws of antiquity.” Most relevant for Hume’s purposes is the fact that his acquaintance Robert Wallace (c. 1744: 22) lauded “our worthy countryman Mr Fletcher of Saltoun” in a draft of his Dissertation on the Numbers of Mankind in Antient and Modern Times (1753). Wallace shared a version of the manuscript with Hume in the summer of 1751, and Hume acknowledged that it was this exchange with Wallace that prompted him to publish his “Populousness” essay the following January (see Amoh, 2003).

Wallace was a Presbyterian minister and communitarian Whig who feared that the market for luxury goods was diverting productive labor away from agriculture. Drawing on statistics from Fletcher’s Second Discourse, he asserted that at least one out of every 15 inhabitants of Scotland were vagrants dependent on public relief. Wallace (c. 1744: 23, 1753: 88) believed “things were quite otherwise” in ancient Europe, when the poor were supported as “the property of rich men.” Wallace was careful to say he was not interested in restoring chattelism. He acknowledged “the cruelty and injustice” of ancient slavery. However, his thesis that Europe had reached its highest population during the Roman republic made him sympathetic to Fletcher’s arguments. Wallace reasoned that ancient slaves were often better cared for than modern servants. While modern masters discouraged their male servants from marrying, ancient householders would have regarded their slaves’ families “as a valuable part of their riches” (Wallace, c. 1744: 23–24, 1753: 89–91). Wallace assumed that slavery as an institution made the ancient world more populous, in so far as slaves benefited from the resources of their masters’ households.

This is the premise Hume worked to refute. His population essay mines a range of ancient sources—many initially cited by Wallace—in support of the opposite thesis that “slavery is in general disadvantageous both to the happiness and populousness of mankind, and that its place is much better supplied by the practice of hired servants” (2021: 290). Hume stressed that servants operate in an economy of mutual “checks.” Bad masters will struggle to hire good servants, while bad servants are unlikely to find a good master. Household slaves, by contrast, confront a system of “unbounded dominion,” in which all checks and duties fall on them alone (2021: 282). The Scottish abolitionist William Dickson would later quote this passage in his Letters on Slavery. Dickson thought Hume’s observation regarding the lack of reciprocity between ancient masters and slaves also described “the colonies of some modern European states,” specifically the conditions in Barbados that Dickson saw firsthand as secretary to the governor (1789: 44). This is not to say that Hume’s support for mutual labor agreements was itself abolitionist, let alone anti-racist. Dickson (1789: 44) regretted that Hume had not “extended” his discussion to contemporary “slave-laws,” and recent commentators point out that none of Hume’s Essays treat the slave trade as their primary topic (Ince, 2018: 109, 119, 125–130; Watkins, 2013: 110). Hume’s disgust for Roman slavery did not stop him from adding his footnote on the inferiority of “Negroe slaves” a year later (2021: 168n6). Nor did the arguments in “Populousness” dissuade Hume from assisting Lord Hertford’s investments in Grenada in 1766. It would be inaccurate, however, to conclude that Hume’s debate with Wallace and Fletcher ignored colonial slavery.

“Populousness” and the New World

In the course of challenging his opponents’ view of the ancient household, Hume paused to acknowledge:

The remains which are found of domestic slavery, in the American colonies, and among some European nations, would never surely create a desire of rendering it more universal. The little humanity, commonly observed in persons, accustomed, from their infancy, to exercise so great authority over their fellow creatures, and to trample upon human nature, were sufficient alone to disgust us with that unbounded dominion (2021: 282).

Hume understood that his population argument had implications for the British empire. The relative poverty of Scotland sent a disproportionate number of its young men to the Caribbean, where Scots participated in all levels of plantation management as government officials, soldiers, doctors, attorneys, and overseers (Devine, 2011). Scottish migration to the West Indies did not accelerate until the 1760s, after the end of the Seven Years’ War brought Grenada, Tobago, St. Vincent, and Dominica into the British empire. But Scottish adventurers had been active in Chesapeake tobacco plantations and the Jamaican sugar trade since the beginning of the century (Devine, 2011; Hamilton, 2005). Did Hume fear slavery was becoming “more universal”? Onur Ulas Ince (2018: 127) objects that the essay’s “oblique” reference to modern slavery is offset by Hume’s “assurance” that no one wished to extend slavery, as if an economic appeal to free labor were enough to make the institution obsolete. Watkins (2013: 109) similarly characterizes the above passage as an instance of “blithe naïveté,” given that American slavery was hardly a dying institution in 1752. Yet Hume’s dispute with Wallace suggests a more nuanced argument.

Wallace’s assumption that the ancient household had improved population and alleviated poverty was proof for Hume that the intellectual “desire” for domestic slavery had not disappeared, even among reform-minded Scots without personal ties to the slave trade. Wallace (1753: 88–90, 167–169) was at pains to argue that the inhumanity of colonial plantations had little in common with slavery in a pre-luxury economy, when masters and slaves lived under the same roof. Hume took the opposite position when he drew an analogy between ancient slavery and the conditions in the West Indies. “Whoever is acquainted with the maxims of our planters,” Hume said, would acknowledge that few slaves enjoy the “privileges and indulgences” of their master’s family (2021: 285–286). Hume noted that the Romans had a specific term for a slave born and raised in the household: verna. He thought it was linguistically significant that Latin has no correlative term for imported slaves; the word for a slave brought to Rome from foreign colonies is simply servus. Hume suspected that this must have been the default condition. If most servi were imported, this would mean that Rome’s slave population was not in fact self-sustaining (2021: 285–286n17). Wallace’s emphasis on the humane treatment of slaves was based on the vernae, or, in other words, the exception rather than the rule.

Hume dismissed Wallace’s vision of the benevolent household and instead compared slaveholders with cattle farmers. This admittedly “shocking” analogy was in fact “extremely just” for capturing the incentives of a slave economy. Farmers raise cattle in the countryside because land and provisions are cheaper outside the urban center. Hume suggested that the same calculation would explain why ancient slaveholders depended on “a perpetual recruit” of male bondsmen from the outlying provinces. He provided a contemporary example: rearing a child servant in London “cost[s] much dearer” than hiring a servant of the same age “from Scotland or Ireland” (2021: 284–285). Hume elaborated in his private correspondence with Wallace in 1753 that “in New york, they seldom raise black Children in their Cities . . .They give them away for nothing to the People in the Country, who raise them” (1954: 31). The lesson, Hume implied, holds true in both ancient and modern economies: urban householders have little economic incentive to look after slave families, and slavery is generally adverse to population growth.

Hume followed his discussion of the Roman vernae with a reference to the West Indies plantations:

It is computed in the West Indies, that a stock of slaves grow worse five per cent. every year, unless new slaves be bought to recruit them. They are not able to keep up their number, even in those warm countries, where cloaths and provisions are so easily got. How much more must this happen in European countries, and in or near great cities? (Hume, 2021: 286n19)

If even slaves in a fertile Caribbean climate failed to keep pace with the natural replacement rate, then readers should be skeptical of Wallace’s claim that Europe’s population peaked during the Roman republic. Hume expanded this footnote in the final edition of his Essays, just after reading Smith’s Wealth of Nations in the spring of 1776:

I shall add, that, from the experience of our planters, slavery is as little advantageous to the master as the slave, wherever hired servants can be procured. A man is obliged to cloath and feed his slave; and does no more for his servant: The price of the first purchase is, therefore, so much loss to him: Not to mention, that the fear of punishment will never draw so much labour from the slave, as the dread of being turned off and not getting another service, will from a freeman (Hume, 2021: 286n19).

Smith’s remarks on the economic inefficiencies of slave labor evidently prompted Hume to return to his quarrel with Wallace and Fletcher. Hume reiterated in 1776 that free hired servants are more productive than slaves, and he made a point of connecting this observation to his earlier analogy between Roman slavery and the West Indian planters.

While it is true that Hume expressed fewer overt objections to colonial slavery than Smith (Ince, 2018: 113–114, 130–131), their respective remarks on the economics of slave labor show the two friends converging on a shared position. Smith (1982: 192–193) borrowed from Hume’s “Populousness” discourse when he asserted in his Lectures on Jurisprudence that slavery “is very detrimentall to population.” Smith’s informed his students that “there were very few vernae, as they called them, in Rome.” The proportion of male to female slaves was so uneven because masters prioritized male slaves who could endure harsher labor conditions. Ancient slaveholders found it cheaper to import bondsmen from poorer provinces, as Smith said was also true “in the West India sugar islands,” where “each year they must import about 1 / 5 or 1 / 6 of the whole” (Smith 1982: 193–194). Hume was not necessarily familiar with the specific content of Smith’s Glasgow lectures, but he would have recognized that the antislavery arguments he read in the Wealth of Nations built on his own inferences about population. Hume returned the favor by incorporating Smith’s emphasis on slavery’s economic disadvantages into the final edition of his Essays.

Hume found many of the population statistics recorded in classical sources to be either implausible or incomplete, not least because “the number of slaves is seldom mentioned” (2021: 306–307). Wallace had accepted Athenaeus’s report that ancient Athens was home to 21,000 citizens, 10,000 “strangers,” and 400,000 slaves (Wallace c. 1744: 11, 15, 25, 1753: 54–57, 91). But Hume was skeptical of the massive disproportion between freemen and slaves in these estimates. Hume multiplied Athenaeus’s numbers by four to account for women and children. This would put the total population of Athens at 1,720,000—larger than London and Paris combined (Hume, 2021: 310–311). Hume questioned how any regime with such a high proportion of slaves could survive without a constant threat of revolt:

No insurrection of the slaves, or suspicion of insurrection, is ever mentioned by historians. . .The treatment of slaves by the Athenians is said by Xenophon, and Demosthenes, and Plautus, to have been extremely gentle and indulgent: Which could never have been the case, had the disproportion been twenty to one. The disproportion is not so great in any of our colonies; yet we are obliged to exercise a rigorous military government over the Negroes (2021: 311). ⁷

On one level, this is a neutral statistical argument, meant to cast doubt on the veracity of ancient historians and to challenge the assumption that slaves reproduce at the same rate as free citizens. On another level, however, Hume’s description of the colonies as a form of “military government over the Negroes” reflects his increasing fear that the British empire was becoming unsustainable.

Hume shared Montesquieu’s view that a “military government” is a formerly “free state” overtaken by its army (Hume, 1932b: 1:134; Montesquieu, 1989: 69–70, 165). He also shared Montesquieu’s sense that eighteenth-century Britain was at risk of repeating Rome’s mistakes. Hume had already observed in his 1741 Essays that “though free governments have been commonly the most happy for those who partake of their freedom. . .they are the most ruinous and oppressive to their provinces” (“That Politics may be reduced to a Science” in Hume, 2021: 43–44). He returned to this theme a decade later and concluded the Political Discourses with a warning that “extensive conquests, when pursued, must be the ruin of every free government” (“Idea of a Perfect Commonwealth” in Hume, 2021: 373). By 1769 Hume wondered in his letters whether “the popular Discontent may not reach the Army, who have a Pretense for Discontents of their own?” He confessed to his publisher that he hoped for “the total Revolt of America, and the Expulsion of the English from the East Indies” (1932b: 2:210). Slavery itself was not the reason Hume favored a break with America; his principal objection to the empire was the enormous strain it placed on Britain’s system of public credit (Hont, 2005: 325–353). But Hume’s characterization of the colonial slave system as an instance of military despotism connects modern slaveholding to his anxiety that colonial expansion threatened the liberty and security of the British regime.

Hume may also have chosen the term “military government” in answer to Jean-François Melon’s essay “Of Slavery.” Melon held in his Essai politique sur le commerce that the spirit of “conquest” and “commerce” must “mutually exclude each other” (Melon, 1738: 136). Yet Melon made a partial exception for the French Antilles. He reasoned that colonies were necessary for the nation, slaves were necessary for the colonies, and “military severity” was at least temporarily necessary for managing the large disproportion between slaves and soldiers (1738: 82). Hume’s French translator interpreted “Populousness” as a direct reply to Melon. In a footnote to his 1754 edition of the Discourses, the Abbé Jean-Bernard Le Blanc asserted, “M. Hume had no other object than to destroy the principles on which M. Melon relies for proving the advantages that society in general could take from slavery” (Le Blanc in Hume, 1754: 2: 87n).

Melon had argued that it was the task of the legislator to look beyond the interest of individuals when determining what degree of “subordinations” is best for the security of the nation as a whole. To this end, Melon praised Louis XIV’s Code Noir (1685) for systematizing a form of legal slavery that would minimize the threat of revolts by regulating the care of slave families. Sounding like Fletcher and Wallace, Melon wondered whether France had created a “form of servitude” that was preferable to the “liberty” of domestic servants, in so far as masters would provide for elderly slaves, encourage their slaves to marry, and look after members of their household in “a kind of habitual friendship” (Melon, 1738: 80–87). Hume’s translator sharply disagreed. Le Blanc’s notes accuse Melon of seeking to reestablish ancient slavery, “while what remains of it on earth depopulates it, & continually degrades humanity everywhere” (Le Blanc in Hume, 1754: 2:52–53n). Le Blanc noticed the similarity between Wallace’s and Melon’s arguments and remarked that, thankfully, “M. Hume responded very well to the reasons of one & the other” (Le Blanc in Hume, 1754: 2:54–55n). For readers of Le Blanc’s popular translation, it would have been clear that “Populousness” was more than an exercise in classical erudition. Hume was engaged in a debate with contemporary apologists for colonial slavery.

Hume would return to his critique of slavery in the History of England, especially as he carried his narrative further back in time. Hume composed the six-volume History in reverse, starting with the English Civil Wars and then moving backward through the Tudor and medieval eras. His initial references to slavery are largely rhetorical and reflect the political idiom of the seventeenth century. For instance, Hume tells us that the “partizans of the commons” insisted on the Petition of Right (1628) because a “free monarchy in which every individual is a slave, is a glaring contradiction” (1983: 5:193). However, the references to slavery become more literal as Hume moves into the “many barbarous ages” preceding “the dawn of civility and sciences” (1983: 2:518).

Hume emphasized that modern English liberty was not the product of ancient constitutional principles or specific parliamentary statutes. Rather, the English owed their liberty to a chain of historical contingencies, not least of which were improvements in global navigation around the year 1500 that enabled long-distance trade networks (Hume, 1983: 3:80–82; Cf. Wallace, 1753: 95). Access to luxury markets had silently revolutionized the structure of English society by redirecting the consumption habits of the nobility. As feudal barons squandered their fortune on “equipage, houses, and tables,” they could no longer afford to maintain their household retainers. This left the “common people” free to escape their servitude and to take up independent trades and industry (Hume, 1983: 3:76). While writers like Wallace made excuses for the “equity” of the pre-commercial household and attributed political corruption to the rise of “luxury,” Hume contended that luxury consumption had in fact paved the way for civic independence. “[A]n industrious tradesmen,” he wrote, “is both a better man and a better citizen than one of those idle retainers, who merely depended on the great families” (1983: 3:76,77). Hume clarified that “slave” was the accurate description for peasants who were sold with the land and who had no mode for acquiring personal property:

If we consider the ancient state of Europe, we shall find, that the far greater part of society were every where bereaved of their personal liberty, and lived entirely at the will of their masters. Every one, that was not noble, was a slave (1983: 2:522).

The gradual disappearance of villenage had “broke[n] the bonds of servitude” and ultimately led to an economy in “[t]he interest of the master, as well as that of the slave.” Not until there was a market for free labor did “personal freedom bec[ome] almost general in Europe; an advantage which paved the way for the encrease of political or civil liberty” (1983: 2:524). This is the theme Hume chose to emphasize in the final paragraphs of the final volume of the History: political liberty was only possible in a society that first had personal liberty, and personal liberty required an economy based on free labor for all. Hume was impatient with Fletcher’s proposal for a new “servitude” in Europe because it promised to reintroduce an economic dependence that had taken centuries to eradicate. Fletcher’s republican priorities led him to believe that political liberty could create economic security, but he ended up apologizing for slavery in the process.

Conclusion

Intellectual historians are currently reassessing the connection between neo-Roman discourse and trans-Atlantic slavery. In May 2021, Oxford University hosted the conference “British Liberty and the Slave Trade” to address the striking “neglect of chattel slavery by historians of British political thought,” including by scholars otherwise alert to the language of domination and empire. The conference advertisement notes that it was Dean Josiah Tucker “who first made the case” that modern republicanism rests on an invidious contradiction. Tucker (1781: 168) observed in A Treatise concerning Civil Government that “The most eminent republican writers,” such as Locke and Fletcher, tolerated the enslavement of others, even while “pleading so warmly for Liberty for themselves.” The Oxford organizers are right that the hypocrisy Tucker associated with the American revolutionaries speaks to a serious problem in the neo-Roman theory of liberty, with its rigid distinction between freemen and slaves. However, they do not seem aware that Tucker was paraphrasing a point his acquaintance Hume had raised 20 years earlier. ⁸

Tucker was not the only British writer to return to Hume’s population discourse when assailing American slaveholders. After the Somerset v. Stewart (1772) and Knight v. Wedderburn (1778) decisions banned slaveholding in England and Scotland, John Millar of Edinburgh revised his Origin of the Distinction of Ranks in 1781 to say:

It affords a curious spectacle to observe, that the same people who talk in a high strain of political liberty, and who consider the privilege of imposing their own taxes as one of unalienable rights of mankind, should make no scruple of reducing a great proportion of their fellow-creatures into circumstances by which they are not only deprived of property, but almost of every species of right (Millar, 2006: 278).

Millar (2006: 271–275) incorporated several references to “Populousness” in the final section of Ranks, making clear he had Hume’s comments on Fletcher in mind. As conflict with America directed a new level of attention to British colonial practices, Hume’s answer to Fletcher could be cited against the New World republicans who had failed to abolish slavery.

This is not to say that everyone accepted Hume as an anti-slavery author. James Beattie of Aberdeen dedicated several pages of his Essay on Truth to denouncing Hume’s footnote from “National Characters.” At a time when North American planters were seizing on the note to rationalize race-based slavery, Beattie accused Hume of blaming the victim. If enslaved blacks in Jamaica had failed to display what Hume termed “symptoms of ingenuity,” this was an indictment of the slave system itself, not evidence of racial differences (Beattie, 1770: 479–484). ⁹ The Scottish abolitionist James Ramsay echoed Beattie when he wrote that the “paradoxical Hume” would hardly be regarded as a genius, were it Hume’s misfortune in life “to have cultivated the sugar-cane, under a planter, in one of our old islands” (Ramsay, 1784: 245; see also, 198–199, 214). Yet Ramsay, too, made a point of refuting Fletcher. He dedicated an entire section of An Essay on the Treatment and Conversion of African Slaves in the British Sugar Colonies to explaining why Fletcher’s distinction between political and domestic slavery was “imaginary and inconclusive, when applied to individuals” (Ramsay, 1784: 45). Fletcher’s agrarian plan would have reduced all Scottish ranks to that of “master and slave,” preventing the very improvements in industry and land distribution that Ramsay said had extended “political happiness and private conveniency” over the course of the eighteenth century (1784: 50–52).

Other early abolitionists like Benjamin Rush and William Dickson renounced Hume’s racism but studied his argument for free labor. Rush’s copy of Hume’s Essays and Treatises, now housed at the Library Company of Philadelphia, includes marginal “XX” marks beside Hume’s comments on Fletcher and domestic slavery (Rush in Hume, 1758: 211). Rush was likely preparing for his remark in An Address to the Inhabitants of the British Settlements in America Upon Slave-Keeping that a country’s population and riches “can only flourish in proportion as slavery is discouraged.” ¹⁰ Dickson paired Hume with Benjamin Franklin as two authors to whom “we have been so much indebted” on the subject of slavery’s effect on population (1789: 150). Dickson, who would soon canvass nearly 50 Scottish towns on behalf of the London Committee for the Abolition of the Slave Trade in 1792, is too conciliatory when he suggests that the “benevolent Hume” would have chosen his words on race more carefully, had he known that the “conjectures” in his footnote would be “magnified into arguments, by the apologists for slavery (1789: 60).” Hume made no effort to remove the infamous note from the six further editions of the Essays prepared during his lifetime. But Dickson conveys his sense of the dual legacy Hume left antislavery campaigners. On one hand, the note to “National Characters” lent a veneer of philosophical authority to those who sought to justify modern slavery on the basis of race. On the other, Hume had shown why slavery impeded economic prosperity and was incompatible with modern liberty.

This article has worked to supply the necessary textual and historical background for understanding why abolitionists who abhorred Hume’s footnote still looked to his discourse on population as a resource for anti-slavery ideas. It is impossible to appreciate the political import of “Populousness” without first knowing that Hume was responding to Fletcher and Wallace, commonwealthmen whose concern for Scottish poverty led them to apologize for ancient slavery. It is also difficult to appreciate the uptake of Hume’s arguments without remembering that his Essays and History were widely circulated throughout the Seven Years’ War and the American Revolution, conflicts that forced British subjects to grapple with the meaning of liberty and the tensions of colonial rule.

Hume’s anti-slavery ideas are not limited to “Populousness.” His emphasis on the “general rules” that apply equally to each member of society (Treatise, III.ii.2.22–24: 497–500) anticipates his argument for the mutual “laws of reason and equity” that regulate the relationship between masters and free servants (2021: 282). Moreover, the “principle of comparison” that informs Hume’s psychology of the passions sheds light on why Hume would take issue with the Roman concept of political liberty, with its constant comparison between freemen and slaves. Finally, Hume’s attention to the economics of free labor recurs as a guiding theme in the History of England, where he insisted that civil liberty was a relatively recent accomplishment. It had first required “personal liberty,” which Europeans did not attain until commercial development broke the bonds of feudal servitude.

Hume’s reflections on slavery were always more academic than abolitionist. But he correctly saw that the same worldview that encouraged eighteenth-century theorists to overestimate the population of ancient Rome also led them to underestimate the injustices of slavery. In supplying the first serious rebuttal to this theory of population, Hume provided readers with a novel set of antislavery arguments, rooted in moral psychology and economic history. Slaveholding was inhumane and inefficient at the level of domestic economy and impeded the justice and security of the overall regime. While Hume’s personal record on slavery was far from perfect, his political writings served as a clear resource for readers who agreed that liberty and slavery cannot coexist.