This article introduces several aspects of eighteenth-century discussions of slavery that may be unfamiliar or surprising to present-day readers. First, even eighteenth-century philosophers who were opponents of slavery often exhibited marked racism and helped develop racial concepts that would later serve pro-slavery theorists. Such thinkers include Hume, Voltaire, and Kant. Second, we must see slavery debates in the context of larger scientific and political debates, including those about climate and character, just political systems, the superiority or inferiority of the moderns (...) to the ancients, and the status of women. This section of the paper discusses the views of Montesquieu, Edmund Burke, Adam Smith, Sarah Chapone, and Mary Astell. Finally, many anti-slavery arguments of the time may seem too ‘soft’ to contemporary readers, as they appeal to negative effects or aspects of slavery rather than arguing for its absolute injustice. The last section of the paper compares Rousseau's arguments against slavery in The Social Contract with such arguments and concludes with a discussion of how Hume's understanding of humanity as a virtue may serve as a bridge between the two. (shrink)