The chapters of this handbook presented slavery both as a global practice having existed from Old Babylonia to the present day and as an institution with globalizing effects connecting people, places, and commodities, sometimes over great distances. The contributions have shown how people have entered enslavement, been exploited as slaves, and attempted or managed to exit slavery across time and space. At any given time, people have been born into slavery and captured or kidnapped by soldiers, warriors, or pirates. They have been sentenced to slavery or sold themselves into it to escape poverty or debt. In all parts of the world, slaves’ bodies and their ability to perform labor have been violently exploited; they have lived in segregation or side by side with other coerced people, and they have served the needs and pleasures of their masters and the respective slaving systems. And throughout history, people have struggled to leave this status of total submission by working and negotiating for their ransom or manumission, or by planning their escape or revolt.

Obviously, all these individual and collective stories of enslavement cut across linear narratives tracing slavery from the Graeco-Roman context directly to Atlantic slavery and abolition. Rather than appearing as a human institution following a simple path of gradual evolution and dissolution, slavery proves to be a chameleon, quickly adapting to shifting circumstances and frameworks by devising new modalities capable of translating proven logics of exploitation into new forms. What, then, can nevertheless be learned from such a broad overview encompassing slaving contexts from many different periods and world regions? What is the scientific benefit of a diachronic and transregional perspective on slavery—apart from acknowledging how many different forms it could assume in its various settings, and how versatile and adaptable existing systems of enslavement were and still are to changing conditions?

This handbook will not conclude with yet another attempt to provide the reader with a revised definition of slavery. While the introduction set out the analytical framework for the study of global slavery, the final chapters on modern slavery have strikingly delineated the dilemmatic discussions on a catch-all term permanently at risk of explaining too much and too little at the same time. What this conclusion will attempt to do in turn is to identify and distinguish logics, modes, and parameters of enslavement across time and space, relating these observations to broader research agendas in historiography.

Global Slavery: Four Logics of Enslavement

Four distinct logics of enslavement emerge from the slaving practices presented in this handbook’s chapters. Each of these logics has its own rationale and its own implications. Notwithstanding the different forms each individual logic could assume, the main rationales appear as sets of converging criteria that may be found throughout history and in all parts of the world. Very importantly, however, one logic does rarely dominate everything, and boundaries between these logics are sometimes blurred. In most settings, two or more logics exist side by side within a specific period and region, and one slave may experience settings of enslavement that belong to different logics.

The first logic of enslavement, which I propose to call the output-oriented logic of enslavement, is centered on the demand for cheap and hard workers. In this logic, the main purpose of enslavement is the extraction of labor—in particular, work that no one else is willing to do. As a consequence, the degree of social stratification and labor division based on status is generally high. Slaves are categorized and valued for their labor capacity and physical fitness, and prices for male slaves therefore tend to be considerably higher in these settings than for female and underage slaves. Slaves work primarily in capital- and labor-intensive industries, often implying hard physical labor in areas such as construction, mining, or plantation industries, or the military sector. The slaveholders may be large landowners and entrepreneurs as well as public institutions such as an emperor, governor, or the state. Depending on the size of the respective construction or production site, slaves often live in social segregation, supervised by overseers. In most of these contexts, land exists in abundance, and wealth and power are expressed through the control of people. Controlling and coercing strong, young men to hard physical labor that no one else will voluntarily perform requires clear restrictions to their mobility and a high degree of (threat of) physical violence and punishment with accordingly significant mortality rates. At the same time, there is a constant risk of escape attempts, sabotage, and rebellion.

The second logic of enslavement, to be called the logic of complementary enslavement, seeks to complement the stock of people at their owners’ disposal and contribute to the economic well-being and social power of the master’s household. The main rationale is to obtain individuals who serve and obey all sorts of needs defined by the slaveholder. Depending on the fields of activity and the socioeconomic position of the owner, these slaves work side by side with other dependent people, without a clear division of labor, in all sectors ranging from domestic services and agricultural work to handicraft and manufacture as well as knowledge production and curation. Slaves are thus not a distinct categorial group within the slaveholding society, even though some services may preferably be delegated to slaves if potential owners can afford their purchase. Despite generally being officially declared unskilled workers, slaves’ specific expertise—be it given or acquired—often becomes difficult to replace in these settings. The owners are mostly private individuals, and the primary reference point is the owner’s household; the slaves may or may not live within this household depending on the specific historical and geographic setting. Their individual destinies depend strongly on the personal relationship with their owners. They can endure the harshest forms of exploitation and violence or be entrusted with the most confidential duties implying a high level of loyalty, such as messenger, treasurer, teacher, or doctor. The personal relation between slave and slaveholder implies an ambivalent intimacy fluctuating between hostility and familiarity; yet the slave is primarily considered a human being, more or less well suited to adapting and converting to the master’s conditions. In these contexts, the majority of slaves are usually female, and female slaves are generally priced higher than men. (Potential) sexual exploitation is a constant epiphenomenon of this slaving rationale. The absolute power of the household master means that the presence of female slaves can be employed to produce heirs, to reproduce slaves, to increase income by renting them out as wet nurses, or simply for the sexual gratification of the male household members. High manumission rates correlate with the high costs of subordination in this setting, and slaves’ hope for improvement and the promise of freedom function as subtle tools of suppression to command obedience. This is doubtless the most common logic and form of slavery in history.

The third logic of enslavement can be called the logic of conspicuous enslavement as it aims to increase the social prestige of the high elites. Here, slaves are marketable surplus products, objects of desire, and luxury goods that are primarily used as status symbols and gifts as well as for personal pleasure and (sexual) gratification. The body of the slave and his or her gender and physical appearance is at the center of this rationale. In many of the societies where the logic of conspicuous enslavement applies, we encounter eunuchs as the highest expression of beauty, obedience, discretion, and loyalty. Given the brutality and the high mortality rate of castration processes, eunuchs are almost always slaves—and by far the most expensive group among them. In the same vein, the beauty of the female body is prized for its capacity to allow concubinage and the maintaining of a harem, while the body of a child is valued for the possibility to impose docility. Exotic criteria such as skin color, body height, or physiognomic anomalies can also play a role in the pricing process. In this rationale, prices do not correspond to any real value; rather, they mirror the cultural capital of the slave owner and the fashion trends of the respective social elites. Most slaves in these settings are traded over long distances, and their place is at court, respectively, in the palaces and other luxury residences of the highest elites of society.

The fourth logic of enslavement is the asset-oriented logic of enslavement. Here the underlying rationale is not focused on the slave as a source of labor, obedient servant, or status symbol; instead, he or she is used and viewed as an object—as a commodity or placeholder functioning as collateral for loans, as means of payment, as a financial asset, or as a way of extracting revenues for further investments. The body of the slave is traded and invested in to create guarantees and to generate and increase wealth. The slave’s gender and physical appearance as well as his or her labor capacity is secondary to this rationale. The trading parties are mostly merchants and entrepreneurs along with representatives of public institutions. The asset-oriented logic of enslavement is either related to the fact that currency as a means of payment is scarce or to the circumstance that slaves are part of commodification processes and long-distance commodity chains connecting production and consumption sites in distant locations. It is mostly encountered in mercantile societies.

Historicizing and Spatializing Slavery: Temporal Modes and Spatial Parameters

Although these four logics of enslavement can be found throughout all periods of history and in all areas of the world, the history of global slavery is naturally not irrespective of historical change and local settings. Three temporal modes and spatial parameters emerge from the chapters of this handbook that cut across these rationales and help to conceptualize long histories of slavery and localize its patterns.

Other than the well-established linear story from the Graeco-Roman context to the Atlantic system and its abolition, it seems that three modes can be distinguished which fundamentally shape the form a specific rationale of enslavement could take: the unregulated mode of slaving, the institutionalized mode of slaving, and the de-legalized mode of slaving. In the unregulated mode, slaves are not a clear-cut social group, and the terminology is blurred. Slaving is a well-known and commonly accepted practice in society with little need for legal regulation. The institutionalized mode of slaving mostly goes hand in hand with a growing influence of central powers such as empire, religious authority, or the state. Criteria of enslaveability establish and maintain the social order by distinguishing potential slaves from people protected against enslavement. They help to constitute and strengthen the community of the ruling class and define the difference between legal and illegal forms of violence and exploitation, and thus between good and bad forms of slaving. Finally, the de-legalized mode of slaving condemns slavery as a codified social institution. The moral discourse on righteous and criminal forms of slaveholding shifts toward a discourse in which the own slaving practices are defended and defined as something other than slavery while those of neighboring or opposing powers are criticized as outlawed and retrograde forms of human exploitation. Very often, the same practices and rationales are simply reframed, mostly depending on the interplay between the state and the ambition of the ruling elites and central powers of society on the one hand and the socioeconomic dynamics of the established logics of enslavement on the other. Not all societies transition through all three modes, and some might move from a de-legalized mode of slaving to unregulated practices again. Therefore, it seems that rather than dividing the history of global slavery into a history before and after Western abolitionism, we should perhaps conceptualize it as a long history of legalization and de-legalization processes in which the three different modes can supplant each other, stagnate, or merge into broader transregional, yet sometimes still distinct abolitionist discourses.

Besides these modes of enslavement that help us to situate slaving practices in historical times, three spatial parameters seem to determine and affect the form the four logics of enslavement can assume. The first of these spatial parameters is the origin of the slaves, that is, the question where slaves come from. The way in which the distinct rationales of enslavement are put into practice heavily depends on whether slaves are taken or generated from within society (for example by birth, inheriting the status of their slave parents; through self-sale or the sale of children due to poverty and indebtedness; or as a means of individual or collective punishment and subjection) or whether they are kidnapped, caught, or traded from a conquered enemy or a neighboring or distant region. Whether and in what ratios slaves are bought, traded, and exploited for domestic needs or for export markets, and whether the producer and consumer societies overlap or are connected through long-distance commodity chains, strongly defines the degree of connectivity local slaving practices are embedded in. The second parameter is the density and location of the slaves. Whether slaves are held in low-density systems as individuals or as one (small) group among others, whether they live as resident slaves in a personal relationship with their masters or form a majority and live in separate high-density habitations, sometimes supervised by overseers, significantly influences the (self-)perception of slaves within society. The third parameter is the (ex-)slaves’ destination—in other words, the timeline of assimilation. Whether slaves are likely to be ransomed, manumitted, or enfranchised (with or without the option of returning to their original families’ origin or starting new families in their own dwellings), or whether the slaving system is instead characterized by high mortality rates and the permanent mark of enslavement over generations clearly defines the social and spatial mobility of the slave. Comparing the sets of spatial parameters in local settings from antiquity to the present day, it appears that the classical division of the history of slavery into the periods before and after the rise of capitalism and Western imperialism needs to be reconsidered. Commodification processes and commodity chains involving long-distance slave trading can be observed throughout all historical periods, and the degree and development of connectivity have never been linear or irreversible.

Situating Slavery Studies: Research Perspectives

In conclusion, a survey of slaving practices with a temporal and geographical scope as comprehensive as the one in this handbook ultimately needs to address the question of what slavery studies stand for today and in which direction this field of research intends or needs to develop. The identification of distinct, but overlapping logics of enslavement with their respective temporal modes and spatial parameters suggests two somewhat opposing scenarios in this context. The first scenario, which I will call the expansionist approach, would aim for a refined definition of global slavery that establishes all four logics of enslavement as four strands of a broader field of slavery and dependency studies. This approach would point to the neighboring fields of research as related forms of extreme exploitation, domination, objectification, and commodification and suggest incorporating all of these forms under the umbrella term of slavery and dependency studies. In this scenario, historians of forced and convict labor would contribute to a deeper understanding of the output-oriented logic of enslavement, while historians of domestic service, serfdom, debt bondage, and corvée labor would expand the notion of complementary forms of enslavement. Cultural historians studying forms of self-representation by social elites would help to situate the logic of conspicuous enslavement within the history of elite cultures, and economic historians would position the asset-oriented logic of enslavement within the history of trade and trafficking. The main purpose would be to expand and reassess the character of global slaving practices in comparison and contrast to other related fields of coercion.

The other scenario would be the diffusionist approach. Rather than incorporating other fields of research into the realm of global slavery studies, the acknowledgment of distinct but overlapping logics of enslavement may allow historians of slavery to conceive these rationales as elements of broader logics of coercion. From this perspective, global slavery is no longer at the center of an expanding research field but functions as one entry point among others for a new social history. The output-oriented rationale of extreme human exploitation suggests addressing the making and unmaking of legal and illegal forms of violence along with the role of public authorities and social institutions in enabling or impeding, defending, or condemning the systematic mistreatment of humans. In turn, the rationale for complementary enslavement contributes to a deeper understanding of the metaphysics of power in all types of labor and kinship relations as well as the interdependent and ambivalent relationship between mastery and domination, between protection and subordination, between promise and obedience. The rationale for conspicuous enslavement targets processes of objectification and the intersecting markers of social inequality enabling or impeding these forms of human degradation, while the asset-oriented rationale of enslavement helps to understand the economic conditions of the commodification of human bodies as well as its consequences, thereby contributing to a new history of capitalism.

The choice between the two possible directions to take is ultimately a political one. There may be good reasons to maintain “global slavery” as a powerful catchword with the purpose of raising awareness for the most extreme forms of human exploitation, domination, objectification, and commodification in the past and present, hoping to mobilize society at large against their present and future manifestations. Or one might choose to focus on the underlying dynamics that point to the potentials and risks of human exploitation, domination, objectification, and commodification in all social and power relations. In both cases, the respective choice necessitates radical contextualization in order to deepen our understanding of slaving practices and avoid hasty instrumentalizations, no matter how well-intentioned they may be.