Berlin wrote this book to revise the dominant image of American slavery in scholarship and the popular imagination: that it was a static institution that varied little across time and space. He proves instead that the whole system developed according to historical contingencies, or conditional sequences of events with no predetermined outcomes. Historical actors at every level of society, from legislators to planters to slaves themselves, made decisions and enacted events that determined the trajectory of history in distinct locations over the course of three centuries.

This framework also reveals that slavery did not evolve in a linear or uniform fashion. Its development varied by location and time period. Berlin centers the history of slavery on the continual negotiation between slave and slaveowner. This essential relationship, albeit irredeemably uneven in terms of power, created a space in which slaves could safeguard critical elements of immediate individual circumstances and larger aspects of slave culture. In giving slaves credit for their actions, Berlin presents them as historical agents that influenced large historical trends.

The example of the plantation revolution illustrates the impact of contingency. In places where planters could grow and export a single, lucrative crop, they established themselves as a ruling class and redesigned societies around the institution of slavery.