Adam Smith on Slavery

Found in Lectures on Justice, Police, Revenue and Arms (1763)
This quotation is taken from Smith’s Lectures on Jurisprudence and reflects his own disgust with what he saw as the immoral institution of slavery. It is a good example of the moral philosophy he expounds in his Theory of Moral Sentiments, in which our sympathy for our fellow human beings forms the basis for moral behavior.
By this we may see what a miserable life the slaves must have led; their life and their property intirely at the mercy of another, and their liberty, if they could be said to have any, at his disposall also. But besides these hardships which are commonly taken notice of by writers, they laboured under severall others which are not so generally attended to. (FROM LJ(A) iii.94) - Adam Smith
Elsewhere, especially in Book III of the Wealth of Nations, his attacks on slavery are framed in economic, not moral, terms. He reckoned that it would, in fact, be extremely difficult for slave holders to ever be able to exercise sympathy with their slaves, since doing so would force a recognition of their own wickedness. Instead, he focused his efforts on arguing that slavery was an economically unfeasible system, far more expensive than using free labor. He was pessimistic, however, that even these robust economic arguments would be sufficient to lead slaveowners to free their slaves, because their economic self-interests would be trumped by their interest in power and domination, which Smith acknowledged were very powerful human drives.
Hence, despite his personal abhorrence of slavery, and his moral and, especially, economic arguments for its abandonment, he was very pessimistic that slavery would be abolished anytime soon, or indeed ever. As it happened, however, chattel slavery ended much sooner than he had anticipated and was abolished in Scotland in 1778. In 1807, Great Britain outlawed the slave trade, and abolished slavery itself throughout its empire in 1833.
(For a thorough overview of Smith’s arguments against slavery, see Jack Russell Weinstein’s essay on the subject at Adam Smith Works. )