Lecture: Slavery
World Civilizations
Was slavery necessary to create our modern civilization? Was it a prerequisite? I say it is as essential as food, shelter, reproduction, or walls. When we think of the prerequisites for civilization, we imagine grain, shelter, walls, armies — perhaps reproduction. Rarely do we ask the darker question: without “slaves,” do we have civilization?
What precedes morality is survival. If a group or tribe spends all their time thinking about food security, they think of nothing else. This is why, in pro-slavery reasoning, slavery becomes a civilizational mechanism: it creates the space in which others can think. Like walls and food security, slavery creates the space in which thinkers can appear. When you are no longer thinking about food, society may produce specialized labor.
If the great Greek playwrights were thinking about food, would they emerge? Plato does not exist — and without Plato, there is no Aristotle. To many of the great thinkers of the ancient world, slavery was framed as an engine of good, an engine of empires, an engine of wealth, an engine of greatness.
At the base of all societies, there has to be a labor system that supports the possibility of the “thinking” class — philosophers, artists, historians, writers, poets. Slavery and civilization have remained hand in glove, crucial to any empire’s development. Does that make it right? Of course not, but morality is what is accepted and justified by a society — morality has been and remains one of the most malleable elements of great civilizations. The malleability of morality has given slavery the longevity that required more than conquest.
Slavery dates back to prehistoric times and was modeled on the domestication of animals. From the earliest periods of recorded history, slavery was found in the world’s most “advanced” regions. The earliest civilizations — along the Tigris and Euphrates rivers in Mesopotamia, the Nile in Egypt, the Indus Valley of India, and China’s Yangtze River Valley — all of them had slavery.
In ancient China, migrants were declared “socially dead” or barbarian outsiders, making justification easy. And it was not incidental. Slavery emerged alongside the earliest known systems of law. The Code of Hammurabi recognized slavery, embedding it into the legal and social order from the earliest days of civilization.
Even as Aristotle would later justify slavery philosophically, his ideas were simply an attempt to wrestle with an institution so embedded and large that it always came to a simple truth: populations grew, cities became impersonal, and order required systems. To structure those systems, as Hammurabi had done before them, civilizations used laws and hierarchies. Slavery did not exist in only one form. Affluent to average peasant households in Northern China, India, Egypt, North Africa, and Europe held one or two slaves to help with agrarian labor and/or household tasks. Large numbers of slaves were also employed in high-risk occupations such as quarrying, mining, and building work.
They frequently worked side by side with corvée laborers (forced labor exacted in lieu of taxes) and prisoners, while household slaves rubbed shoulders with seasonal employees, and could be hired out for a wage as well. Slavery was built into the socio-economic system of ancient agrarian states. But only under the Roman Empire did slave employment become a strategy for market-oriented agrarian enterprise. Roman villa estates were typically both run by a qualified slave manager (vilicus) and cultivated by large numbers of chattel slaves.
The first true slave society in history emerged in ancient Greece between the sixth and fourth centuries BCE. In Athens during the Classical Period, a third to a half of the population was enslaved. If that were the United States today, that would mean 100 to 150 million people would be slaves, if not more. This is insane when we think about slavery proportionately. To the great thinkers of the world, slavery required distance from civilization. Not necessarily physical distance (though that is the situation we find ourselves in today), but a moral and social distance — between the enslaver and the enslaved.
The ancient Greeks grappled with this and justified slavery through a simple idea: only those not of their tribe were fit to be slaves. The Greeks, in their superiority, were thinkers worthy of freedom. This need for differentiation became philosophy, and the world’s great thinkers have justified slavery or its existence in their societies for thousands of years.
One of the greatest examples of this justification is Aristotle. He constructed the notion of the “natural slave” — those who, in his view, lacked the higher qualities of the soul necessary for freedom. Aristotle saw slavery as right and just because it reflected societal norms. He also believed some (non-Greeks) were naturally suited to be slaves.
Aristotle identifies slaves as property, property as part of the household, and slaves as just another “instrument” of the home. Aristotle claimed, “…he who is by nature not his own but another’s man, is by nature a slave.” He justified his thinking within the context of societal norms and societal “nature.”
“Where then there is such a difference as that between soul and body, or between men and animals (as in the case of those whose business is to use their body, and who can do nothing better), the lower sort are by nature slaves, and it is better for them as for all inferiors that they should be under the rule of a master. For he who can be, and therefore is, another’s and he who participates in rational principle enough to apprehend, but not to have, such a principle, is a slave by nature.”
The Law Code of Gortyn, circa 450 BC, is considered the oldest, most extensive, surviving legal code of the ancient Greeks (inscribed on stone columns in Crete) — predating Aristotle (384–322 BC). The Code of Gortyn detailed ideas on property, marriage, and slavery, including early Greek legal sophistication and family structures, and even rights for women in divorce.
Nearly 900 years later, the Codex Theodosianus (compiled between AD 429 and 438) formalized the legal status of slaves in the late Roman Empire. It maintained a system that classified slaves as property subject to purchase, sale, and punishment, while also reflecting shifting morality: outlawing facial branding, replacing tattoos with collars, restricting Jews from owning Christian slaves, and upholding laws that rendered children of slave mothers as slaves. The Roman legal world, built atop Greek intellectual inheritance, developed rigid categories through which people were sorted — free or slave — with even portions of the non-slave population living as de facto slave-like individuals.
We can trace laws like these back a thousand-plus years, as Christianity drew on earlier Roman law during the colonization of the New World — those who were “Christianized” technically could not be slaves, though theory and practice are two entirely different things. There was always a need to differentiate the slave from the dominant or victorious society — you cannot have elites if they do not have laborers providing the food on which they sustain themselves.
Rome would become even more dependent on slavery than the Greeks had been. Slavery became a Roman enterprise. Julius Caesar used slavery as an engine of wealth, a lubricant of greatness. The Roman world embraced slavery and death in the colosseum. Caesar stormed through Gaul, expanding the Roman Empire and his personal wealth.
Slavery was part of the spoils of war, a means to humiliate enemies and impose forced compliance. The story of Caesar and Vercingetorix illustrates this clearly: Vercingetorix surrendered himself and his people to slavery to prevent extermination. On Caesar’s conquest of Gaul, roughly a third of the population was killed, a third enslaved, and the remainder subjugated. This is the framework of an empire — slaves are labor, producers of food for armies, builders of monuments to power.
In truth, slavery was a commodity. Markets had preferences. Certain physical traits were desired — sometimes blue eyes, red hair, or simply reproductive capacity. Slavery for most of history was not about race, but about “othering” for justification — by tribe, region, or physical distinction.
As with most ancient systems of power, the keystone was women. Slavery was no exception. The slave trade focused heavily on women, valued as concubines, laborers, and reproducers. Men were often excluded from the treasures of war’s victory, typically killed as they presented danger and rebellion. The analysis of slavery suggests, yet again, that women and food were perhaps the two most important elements of civilization.
It is not an accident that modern ideas of freedom and democracy emerged from slave societies. Slavery and freedom are the “Yin and Yang” of early civilizations. Most early societies lacked a word for freedom, but mass slavery in Greece and Rome made freedom legible. In Roman law, you were either free or a slave. Most early societies lacked a word for freedom, but large-scale slavery in classical Greece and Rome made people more aware of what freedom actually meant. If you don’t know what freedom is, what liberty is, do you yearn for it? Is this why we see Cicero and Plato write their versions of The Republic?
Does Cicero write, “I prefer dangerous freedom over peaceful slavery” in a free society? Or, “Freedom, when long suppressed, bites back more fiercely.” Or does Civis Romanus (“I am a Roman citizen”) mean anything in a society void of slavery?
Slavery is at the core of freedom ideology — it is the contrast that gives morality shape. Slavery never disappeared. Medieval Europe practiced slavery in Sicily, southern Italy, Russia, southern France, Spain, and North Africa. Most slaves were “white,” drawn from Eastern Europe or the Black Sea region. Slavery was normalized.
The New World was no exception to these long-standing patterns of slavery. Long before European arrival, Native American societies practiced slavery, often viewing it as a normal outcome of social hierarchy, misfortune, debt, or war.
Among the most well-documented examples are the societies of Mesoamerica and the Andes. In Incan society, enslaved individuals could be physically marked—faces branded—to signify status and separation. In Aztec society, slavery functioned within a complex economic and ritual system and was not limited to prisoners of war or criminals. When the economic order was destabilized by environmental catastrophe, people sometimes willingly sold themselves into slavery as a means of survival.
In 1446, a massive plague of locusts devastated crop yields throughout the Basin of Mexico. This was followed by catastrophic floods in 1449 that disrupted social life, agricultural production, and confidence in political and religious leadership. These crises pushed many Aztecs into slavery. Perhaps the most striking example occurred during a four-year flood, which forced large numbers of people to sell themselves into slavery in distant parts of the empire simply to survive—imagine a world in which the enslaved were sometimes better fed than the free. At the same time, male slaves captured by the Aztecs in war faced a different fate altogether: they were sent to be sacrificed to the gods.
In much of the ancient world, slavery was not inherently hereditary; enslaved status did not automatically pass from parent to child. The Aztec case complicates this pattern. While slavery itself was not directly hereditary, debt could be passed down through generations, and that debt could, at times, result in hereditary enslavement. Rome and China shared similar distinctions between servile and non-servile identity categories that deeply structured society and belonging. In Egypt, conditions could be so severe that individuals voluntarily sold themselves into what was known as “temple” slavery.
Africa, too, possessed ancient slave systems that long predated European contact and differed significantly from the plantation slavery that would later dominate the Atlantic world. In many African societies, hereditary slavery was rare, and enslaved individuals were often absorbed into households or kinship networks over time rather than permanently excluded from society.
Europeans, for their part, were well acquainted with slavery long before Columbus. By as early as 1300, sugar plantations in Italy relied on enslaved labor, and by the 1400s, Europeans were exploiting African labor on sugar-producing islands off the West African coast. When indigenous populations in the Americas collapsed under the weight of disease and conquest, slavery did not merely continue—it expanded at an unprecedented scale.
It was in the New World that slavery hardened into something fundamentally new: racialized, permanent, and capitalist. Unlike classical slavery, which existed within diverse labor systems, New World slavery became the central labor engine of plantation economies producing sugar, cotton, coffee, and other commodities for distant global markets. In both scale and logic, it represented a transformation.
Yet in fundamental respects, New World slavery differed from slavery in classical antiquity, Africa, eastern and central Asia, and the Middle East. Slavery in the ancient and early medieval worlds was not originally based on race. As late as the fifteenth century, slavery did not automatically mean Black slavery. Enslaved people came from many regions—the Crimea, the Balkans, and the steppes of western Asia, among them.
Racial slavery emerged gradually during the Middle Ages, as Christians and Muslims increasingly recruited slaves from eastern, north-central, and western Africa. After 1453, when the Ottoman Turks captured Constantinople and disrupted traditional slave routes, Christian slave traders drew more heavily on captive Black Muslims—often referred to as Moors—and on people purchased along the West African coast or transported across the Sahara. Even then, most slaves in Africa, the Islamic world, and the New World prior to European colonization worked as farmers, household servants, concubines, or eunuchs. They were often symbols of prestige, luxury, and power rather than the primary source of labor.
In the Columbian period (after Columbus conquers), there was a great need to differentiate the European from the “others”—the Sistema de Casta, developed long before Columbus, it was used to differentiate Muslims from Europeans of Iberian society during Reconquista — the Spanish simply took what they had learned from hundreds of years of fighting with the Muslims and applied it to Native Americans.
When the Native American slavery did not work (as some 90% of the population died), African slavery became a suitable replacement. But, not even then was slavery based on race in North America — that would not happen until a series of rebellions by landless whites did those in the English colonies seek to move toward a race-based system for clearer delineation of elites, the working class, and the slave class.
Divide and conquer.
By the time of the American Revolution, slavery was already deeply embedded in society. Pro-slavery ideology both drew from—and resisted—the Enlightenment, particularly its language of natural rights. Thinkers selectively borrowed from John Locke, embracing ideas of natural law and rights by birth or from God, while rejecting the premise of natural equality. Instead, they converted Enlightenment thought into an argument for “natural inequality,” asserting that humans were not born with equal capacities or abilities, and that hierarchy was therefore justified.
Slavery has had profound consequences in human history. Without it, many of the large-scale events that shaped civilization would not have occurred. That does not make it right—but it happened. Slavery is the shadow behind freedom, the contrast through which liberty was defined.
And slavery has not vanished. There are still slaves in the world today—the Uyghur Muslims in China are one example. Even so, for most civilizations, slavery was never the dominant form of labor. Only a handful of societies made it so. But when they did, it operated on a massive scale.
Bibliography | Notes
Frankopan, Peter. The Silk Roads: A New History of the World. New York: Alfred A. Knopf, 2016.
Reséndez, Andrés. The Other Slavery: The Uncovered Story of Indian Enslavement in America. Boston: Houghton Mifflin Harcourt, 2016.
The Law Code of Gortyn (Crete).
The Twelve Tables of Roman Law.
“Law in the Ancient World.” Tulane University Law School. https://online.law.tulane.edu/articles/law-in-the-ancient-world
Watson, Alan. “The Evolution of Law: The Roman System of Slavery.” The Journal of Roman Studies 70 (1980): 117–131. https://www.jstor.org/stable/2707403
“Aztec Legal System.” Tarlton Law Library, University of Texas at Austin.
https://tarlton.law.utexas.edu/aztec-and-maya-law/aztec-legal-system
“Aztec Judicial System.” Tarlton Law Library, University of Texas at Austin.
https://tarlton.law.utexas.edu/aztec-and-maya-law/aztec-judicial-system
“Aztec Criminal Law.” Tarlton Law Library, University of Texas at Austin.
https://tarlton.law.utexas.edu/aztec-and-maya-law/aztec-criminal-law
“Slavery and the Atlantic World.” Digital History, University of Houston.
https://www.digitalhistory.uh.edu/disp_textbook.cfm?smtID=2&psid=3027
https://www.digitalhistory.uh.edu/disp_textbook.cfm?smtid=2&psid=3028
https://www.digitalhistory.uh.edu/disp_textbook.cfm?smtid=2&psid=3029
“Slavery and the Roman World.” BBC Radio 4.
https://www.bbc.co.uk/programmes/p00548jd
“Slavery: A World History.” BBC Radio 4.
https://www.bbc.co.uk/programmes/b09xnl51