NO ONE today defends slavery or thinks it anything but bad. Yet before 1760, as Professor Davis reminds us, "black slavery was generally assumed to be a necessary and 'progressive' institution," and not just in those places where plantation agriculture was booming on the strength of slave labor, but in the most active centers of American and European intellectual and economic life. "But during the next thirty years there occurred a profound change" and a "general consensus that black slavery was a historical anomaly" arose in those same centers of "progressive" thought and action. Slavery and Human Progress anatomizes this remarkable change in the climate of opinion, and explores its practical consequences down to the final extinction -- or near extinction -- of slavery in our own time.

The book divides into three nearly equal parts: I -- How "Progress" Led to Europeans' Enslavement of Africans; II -- Redeeming Christianity's Reputation; III -- Abolishing Slavery and Civilizing the World. As Davis explains in the introduction, the first of these parts goes over ground already handled in magisterial fashion by his earlier book, The Problem of Slavery in Western Culture and brings some of his earlier judgments into harmony with more recent scholarship; but parts two and three constitute a kind of reconnaissance for a projected volume, The Problem of Slavery in the Age of Emancipation, and are based on new exploration of primary sources as well as a painstaking mystery of secondary literature.

The most striking characteristic of this richly learned book is Davis' sensitivity to ambiguities and ambivalences. The odd and striking fact that gives the book its title and central problem is this: slavery was defended and attacked on the same ground, i.e., in the name of progress. Enslavement, after all, saved souls and allowed backward Africans to learn new skills and thus contributed to the progress of civilization, quite apart from enriching Europeans. But emancipation, by removing the moral stain of slavery from the world, was also advocated as a contribution to the progress of humanity and civilization.

OTHER STRANGE juxtapositions clustered around this central ambiguity. Thus, for example, the main energy behind abolitionist agitation arose from religious and moral conviction, often expressed in highly charged eschatological terms. But confident decipherment of God's will went along with an obbligato of appeal to cold-blooded self-interest, since free labor entering a suitably managed labor market was declared to be cheaper and more efficient than slave labor. Then, after slavery had been outlawed in the British and French empires, a moral crusade against slavery in other lands accelerated and justified European imperial expansion in Africa and the Moslem lands of the Near East.

It is impossible to do justice to the scope and subtlety of this work by hasty summary or scattered quotes. Still, a few samples may help. Davis devotes a chapter to the Jewish experience of slavery and the codification of Jewish law with respect to slaves. This, he suggests, provided 14th-century Christians with a pattern for their practice of slavery when they took over the Black Sea slave trade from Jewish merchants, and, incidentally, firmed up Biblical sanctions for slavery as a God-given institution. But then, oddly, in the first decades of the 19th century, British Protestant Christianity abandoned Biblical sanctions for slavery by borrowing some essential ideas from the godless Enlightenment and made emancipation a religious crusade. In Davis' words: "Christianity had been leached of its vitality by the Enlightenment and the treason of clerks; shocked into a reactionary hysteria by the French Revolution; contaminated by prosperity and worldly compromise -- but it could still be redeemed and resurrected by its victory over black slavery. Christianity as 'practical benevolence' could then meet the demands of a new industrial age." By the 1840s, "Christianity had at last proved that it could be far more 'progressive' than the revolutions spawned by the infidel Enlightenment, even when measured by the Enlightenment's standards of secular freedom and happiness."

Two chapters are devoted to a careful analysis of British emancipation, which Davis calls "a deceptive model" -- deceptive for the United States that is. His account of the tortuous, almost accidental way in which the prohibition of slave trading (1807) and emancipation of all slaves under British jurisdiction (1833) got through Parliament emphasizes individual action and the alliance of "evangelical appeals to sin, guilt, retribution and deliverance" with "highly utilitarian analysis of punishment, nutrition, land use, labor incentives, productivity and revenue." Old-fashioned religion and newfangled social science thus came together in a strange and wonderful way, largely, Davis suggests, on the basis of a shared conception of social order and moral progress.

Yet leadership of the anti-slavery cause paid enormous dividends for Great Britain. Despite all the "tangle of contradictions and conflicting interests" it "enhanced Britain's moral prestige and contributed to what Jawaharlal Nehru referred to as "the calm assurance of always being in the right." And that same assurance sustained the intensified aggressiveness of British empire builders in the late 19th century, even when the original idealism of emancipation had worn thin and been replaced by a more and more overt racism.

AS DAVIS SAYS himself, he is not much concerned with underlying causes and tries only to discern how "slavery and emancipation were perceived, understood, explained, symbolized, and related to larger frames of reference." The story of how ideas and actions intertwined and separated, dissolved into one another and took on new forms is complicated enough, and it is unkind to ask that the author also address aspects of the phenomena of which the participants were not themselves aware. Still, if Davis had thought fit to connect the great watershed between European views of slavery before 1760 and those after 1790 with the changing pattern of European and world demography, I, at least, would have been better pleased with the book.

Abundant, and overabundant, population makes resort to legal compulsion of labor unnecessary; and the abhorrence of slavery that flourished so mightily in the British Isles in the later 18th and 19th centuries coincided with an unexampled growth of British population that strained job opportunities to the limit. Surely, a stable or shrinking population with accompanying labor shortage at home would have sustained a different climate of opinion. The demographic dimension, modified by differential resistance to disease between Europeans and Africans in tropical environments to which African diseases had penetrated, had a great deal to do with the abolition of slavery and other forms of forced labor in the past two centuries. Perhaps Davis will address this side of things in his forthcoming volume. Its omission here is the only flaw I can find in an admirable, learned, and genuinely wise book.