The late Sir Moses Finley famously drew a theoretical distinction between what he called ‘genuine slave societies’ and ‘societies with slaves’, restricting the former to just five cases in world history, two from antiquity and three from the New World: classical Athens and Roman Italy, modern Brazil, the Caribbean and the US South. The designation of ‘genuine’ depended on evidence of three elements: a substantial percentage of slaves, at least twenty, in a given population, a significant servile role in economic production and a pervasive servile impact on a society's overall culture. The proposition was stated most fully in Ancient Slavery and Modern Ideology (1980), a book that has had a wide influence on slavery studies at large. The present collection, the product of a conference at the University of Colorado at Boulder in 2013, tests its viability from a global perspective, with contributions from an array of historians and social scientists on the history of slavery not only in Finley's five cases, but also in Tropical America, the Pacific Northwest, East and West Africa, the Middle East and Asia, in small-scale and developed communities alike. Its underlying assumption is that slavery by definition lends itself to cross-cultural and interdisciplinary investigation. The book offers no definitive answer to the question its title poses, but its contents are stimulating and informative throughout.

The prime discussant is Lenski, one of the book's co-editors, who in two extensive and invigorating chapters comprehensively deconstructs Finley's theory, and from an enviably impressive command of comparative material replaces it with an alternative of his own. He argues that Finley's dichotomy fails due to its ‘ethnocentrism’ and ‘categorical imprecision’ (p. 15), and urges adoption instead of a model based on ‘intensity’ more suited to the wider global record, in which the key variables are ‘benefit to the master class, disadvantages to slaves, and demographic significance’ (p. 57). He considers measurable the differences among societies in benefits to masters and levels of domination of slaves, and tabulates them in a series of graphs comparing, first, Rome with the US South and, second, Rome and the US South with Siam, Dahomey and Korea. Reacting to O. Patterson's celebrated, but apparently flawed, formulation in Slavery and Social Death (1982), he also includes a new definition of slavery itself which stresses the all-important notion of property:

The result, Lenski believes, provides a new way to analyse what he justifiably calls ‘the bewildering variety of slave systems that have arisen in world history’ (p. 57).

The remaining contributors vary considerably in their response to the rival theories. Writing on classical Greece, P. Hunt finds Finley still useful and makes the immediate point that ‘slave society’ is a far less stable concept than Lenski assumes (p. 63). K. Harper and W. Scheidel broadly concur on Rome, but they reject Finley's primitivist explanation of the growth of slavery in favour of a market-driven view. A.C. Rodrigues also thinks Finley is still partially valid for colonial Brazil, yet R. Gudmestad on the US South finds him reductionist. M.S. Hopper is inclined to follow Lenski in his discussion of nineteenth-century Eastern Arabia, but in a chapter on Ottoman and Islamic slave societies E.R. Toledano sharply rejects Lenski's model altogether, contending that it simply rearranges the constituents of Finley's proposition. (His counter argument, that true slave societies give rise to abolitionist movements, does not work for antiquity.) In some cases little attention is paid to either theorist, as with T. Singleton on the Caribbean, B.K. Freamon on East Africa and the Persian Gulf, and K. Bok-rae on Korea – which is not to say that what is said is without interest. Meanwhile, F. Santos-Granero, discussing pre-contact Tropical America, thinks that any society that condones slavery is a slave society.

In a study of native American slavery C. Snyder is surely right to conclude that Finley's paradigm needs to be modified in order to accommodate the wealth of new discoveries in global history of recent decades. And as has long been known, especially from the work of Africanists, the canonical number of five genuine slave societies obviously cannot stand. (Mention might also be made of the stubbornness inherent in what F. Millar once called Finley's ‘anti-empirical tendency’.) Nonetheless, whether this means that Finley must be discarded entirely will remain a matter of debate to judge from this collection as a whole. That a spectrum of slave societies is discernible in world history, dependent on contingency and cultural specificity, as A. Reid on Southeast Asia and several other contributors maintain, seems to me indisputable, perhaps ironically so given that Finley frequently used the metaphor of a spectrum when discussing ancient social organisation in general and servile statuses in particular (not always recognised: e.g. p. 272). Some hope might still be left therefore for those Lenski chastises for past adherence to him.

I think it fair to say that the comparisons presented in Lenski's graphs are not as objectively secure as they seem. In his formulation of master's domination and slave's disadvantage several factors are in play: the likelihood of manumission, the levels and types of violence inflicted on slaves, the degree of social distance between slaves and masters, and the degree of social dishonour inherent in servility itself. These items have been ‘rated’ and ‘measured’ from ‘personal knowledge’ and the slave societies concerned duly ‘ranked’ (pp. 53, 136, 137, 143, 144). Yet as far as I know, there is no reliable statistical evidence to show unequivocally the rate of manumission of slaves at any time or in any place in Roman history, any more than there is to show the number or proportion of slaves in the population as a whole. Estimates are possible, but no matter how sophisticated they remain no more than that, and as Finley said in The Ancient Economy (1973, p. 71), ‘genuine quantification’ and ‘number mysticism’ are not the same. Nor do I find it plausible that the physical and psychological effects of violence inflicted on individual slaves, in different times and places, in a single society or cross-culturally, can be effectively reduced to numbers. My sensitivity to pain and shame might be far weaker than yours, but how it can be meaningfully measured now, or compared with that of actors in global historical contexts, I find problematical. Violence in any case is an unstable category. While carefully elaborated, therefore, the comparisons seem to me impressionistic only, and they may well mislead if taken at face value by scholars less knowledgeable of antiquity than Lenski himself. As it is, classical historians might well raise an eyebrow (or two) when sweeping generalisations or assumptions about ancient ‘Greece’ and ‘Rome’ are met here, with factors of chronology, geography and evidence clearly underestimated (e.g. pp. 287, 330, 338, 359; the necessary calibrations are brought out by Hunt and by Harper and Scheidel). I hesitate to draw implications from the doubtless unintended but grammatically jarring contrast between slaves and masters in Lenski's definition of slavery. But to my mind the formula's value is adversely affected by its inconsistency of expression. At the same time, Lenski's treatment of Finley's intellectual history is excellent.

These matters aside, there is much for any ancient historian to appreciate in the chapters, the majority, on slave societies other than those of classical antiquity, not least because they suggest possible avenues of further research. I was struck for example by the regularity with which the contributors write of slavery as an ‘institution’ without asking how a well-attested practice or habit, the act of enslavement itself, leads to the establishment of a defined condition or status in a given society. P.E. Lovejoy's chapter on slavery in West Africa, in which he categorises some communities as ‘stateless’, particularly sharpens the question, but it is also relevant, I think, to the new theory of intensification. The creation of a law code regulating slave behaviour is an obvious way in which institutionalisation might be observed, but the processes involved in taking this and related steps could well be a subject for further comparative assessment. My point is that ‘institution’ is a far more formal concept than the ‘practice’ of the book's subtitle. Similarly, many contributors allude to the efforts made by the enslaved in the societies severally examined to escape enslavement, so that resistance emerges as a global constant wherever slavery has manifested itself, as an already voluminous scholarly literature confirms. (Major studies from what I have elsewhere called a golden age of historiography on New World slavery are still pertinent to the present chapters on colonial Brazil and the US South.) As the orbit of enquiry expands, however, the subject calls for further investigation, not least (again) because it is germane to the project of recovering the ‘lived experience’ of slaves that Santos-Granero (p. 194) and Toledano (p. 365) believe essential for understanding what a slave society is, a worthy strategy indeed if one hardly as novel as they assume. It involves inter alia recognition of the psychological effects of slavery, on masters as well as on slaves, a topic that receives only passing mention here, but one to which Finley drew attention as early as 1968 in his seminal entry in the International Encyclopedia of the Social Sciences. He was equally alert to the issue of slave resistance tout court.

The book's special achievement is to illustrate in the light of new and wide-ranging material how Finley's views of the number and nature of slave societies can no longer be maintained in their entirety, even as they continue, almost a generation later, to exert an influence on those engaged with the global history of slavery. (The elegance with which he expressed them remains impervious to criticism.) Also, and perhaps more importantly, by revealing in relatively small compass the ubiquity of slavery in world history, the book raises the implicit question of whether the desire for mastery, libido dominandi as the Romans knew it, and the resistant response its implementation provoked, should be considered elemental aspects of the human condition. The descriptions and analyses of slave systems the book provides do not make for uplifting reading, but as Snyder properly observes (p. 190), they have presentist ramifications of consequence. In its relevance to contemporary social concerns, the manner in which a slave society is defined is an issue that transcends the merely academic.