Did Britain end the slave trade out of conscience, or because it stopped paying?

Historians still argue about it, and the answers point in opposite directions. Eric Williams, who later became the first Prime Minister of Trinidad and Tobago, published Capitalism and Slavery in the United States in 1944. It was, in the source's words, a frontal attack on the idea that moral and humanitarian motives were key to the victory of British abolitionism. Williams argued that abolition was driven by diminishing returns, after a century of sugarcane raising had exhausted the soil of the islands. Major publishers refused to publish it in Britain, and one said he would never publish such a book because it suggested abolition happened for economic and not humanitarian reasons.

Later historians pushed back. Seymour Drescher's book Econocide argued the opposite: the slavery-based economy of the British West Indies continued to be profitable before 1815, and abolition caused the decline, not the other way around. Heuman states that more recent research has rejected Williams's conclusion, since the British Caribbean colonies profited considerably during the Revolutionary and Napoleonic Wars. Meanwhile British ships landed nearly 400,000 enslaved people between 1791 and 1800, and a further 266,000 between 1801 and 1807.

Yet the argument is not simply moral versus money. Williams himself argued that evangelical antislavery and slave rebellions from Haiti to Jamaica also played a part. And Drescher, a prominent critic, wrote in 1987 that if one criterion of a classic is its ability to reorient our view of a subject, Williams's study supremely passes that test. Even an earlier critic of English altruism, W. E. B. Du Bois, writing in 1948, gave conscience a part: he judged that economic factors were dominant, but said it would not be right to question the sincerity of Wilberforce and his followers.