THE AUTHORS of Time on the Cross are nothing if not considerate. They have an array of revelations, some less startling than others, about American slavery. They say it was highly profitable, economically viable, and "35 per cent more efficient than the northern system of family farming." They also conclude that slaves were hardworking, members of solid families, and better fed on the average than Americans in 1879. So they begin their book of cliometric history (history based on statistical analyses) with a chapter of reassurance. "Some of the discoveries were at one time as unbelievable to the cliometricians as they will be to the readers of this volume," they explain soothingly. "This will be a disturbing book to read."

The degree to which it has apparently disturbed the historians who've reviewed it--and this despite its readability and reliance in many of its important sections on the same sorts of non-statistical proof historians have always used--speaks creditably for the strength, if not the depth, of most historians' antislavery feelings. Like other history books, Time on the Cross is open to serious question, both on its facts, which it would presumably take further research to judge conclusively, and on their interpretation. For example, Fogel and Engerman put some stress on the 1850 census's finding that after 230 years of slavery only 7.7 per cent of slaves were mulatto. Such a finding doesn't appear to justify Abolitionist claims that the pre-war South was one big brothel. But neither does it attempt to measure whatever lesser forms of sexual exploitation of slaves occurred. Or, as Fogel and Engerman themselves put it, "while the cliometricians have been able to construct reasonably reliable indexes of the material level at which blacks lived under slavery, it has been impossible, thus far, to devise a meaningful index of the effect of slavery on the personality or psychology of blacks."

Time on the Cross addresses itself to these questions anyway, in one of its most important chapters, on the slave family. Fogel and Engerman maintain that slave families were strong, nuclear patriarchal families--just the reverse of the stereotype popularized by Daniel Patrick Moynihan, or the picture of uprooted slaves forced to recognize only their masters as father figures that Stanley M. Elkins '49 paints in his eloquent Slavery.

APART FROM showing that slave women generally had no children till they married (at an average age of 22.5), Fogel and Engerman present little positive statistical evidence for their position. Instead, they just ask some reasonable questions: wouldn't business motives and moral scruples combined be a strong enough combination to keep planters from tearing apart families when they didn't have to? Why wouldn't the rich owner of a large plantation just keep a mistress in town, where she wouldn't trouble his wife or his labor supply? Or, if masters were so sexually attracted by their slaves that they didn't care about all this, why were there very few black prostitutes in the South? Finally--it's a question Fogel and Engerman never tire of asking--since the evidence for pervasive disruption of black families is less than convincing, why has it so often been taken for granted?

Fogel and Engerman blame it on the racism of most Americans, an often unconscious racism that makes them take black people's weakness for granted and restrict themselves to trying to explain it as an inborn quality or, for the more liberal, as a consequence of oppression. In their epilogue, Fogel and Engerman say they wrote Time on the Cross to attack this view and to show that even under slavery, black people were among the most accomplished and admirable people in the United States, "to strike down the view that black Americans were without culture, without achievement, and without development for their first two hundred and fifty years on American soil."

Such an aim is certainly admirable. But Time on the Cross--whatever the validity of its individual findings--actually goes even further than attacking racism in attacking traditional approaches to American history. For the power of a view like Elkins's--even in its discussion of such topics as what "Sambo" really meant--is too great to dismiss as merely racist. It belongs rather with the old Abolitionist tracts, or even with the modern and equally important tracts of people like C. Wright Mills, moving and evocative in their assertion that capitalism grinds down the humanity of labor. It derives from horror--maybe a horrified surprise--that things have gone wrong, and it attacks history as though history itself had malicious intentions.

Tracts are important. But they aren't history, and if their obliviousness to cold fact becomes essential to them they may not be too convincing even as tracts. An indictment of capitalism or of slavery that depends on the inhumanity or partial inhumanity of their victims isn't likely to last as long as one that accepts their full humanity, and makes that the grounds for its polemic. Whatever the final verdict on the specific findings of Time on the Cross, it's hard to fault its assumptions--that human beings, masters and slaves, will generally on the average act more or less decently if they have the chance, and that that is the reason that slavery or its successor forms of oppression should not exist.