Adam Smith was clear about the evils of slavery. In both The Theory of Moral Sentiments and The Wealth of Nations, he exposed the injustice of the institution and the commercial interests that helped sustain it.
In The Theory of Moral Sentiments, Smith invites us to consider how an impartial spectator, free from personal interest, would judge human behaviour. Applied to slavery, the moral problem is obvious: how can one human being legitimately claim ownership of another?
Smith also examined what he called the “unfortunate law of slavery”. Legal protections for enslaved people were often ineffective because the master held overwhelming power over them. The law might nominally recognise their rights, but those rights counted for little when the person expected to enforce them was subject to the very person accused of violating them.
His economic argument was equally direct. In The Wealth of Nations, he wrote:
“The work done by slaves, though it appears to cost only their maintenance, is in the end the dearest of any.”
Smith explained that someone who could acquire no property had little incentive to work beyond what punishment compelled. As he observed, a person who “can acquire no property, can have no other interest but to eat as much, and to labour as little as possible”.
Free labour, by contrast, offers an incentive to work for personal benefit. Enslaved labour depends on coercion, with effort extracted by “violence only, and not by any interest of his own”. The apparent saving in wages concealed the costs of compulsion and lost incentive.
Smith also attacked the colonial monopoly system. In The Wealth of Nations, he argued that trade restrictions served powerful commercial interests rather than the public. As he wrote, “it is the interest of the merchants and manufacturers of every country to secure to themselves the monopoly of the home market”.
Colonial trade was channelled through arrangements that protected favoured British merchants, restricted competition and burdened consumers. Slavery fitted into this system: enslaved people produced sugar, tobacco and cotton, while trading restrictions helped enrich plantation owners and merchants.
Smith recognised that concentrated commercial interests could use political power to benefit themselves at everyone else's expense. Monopoly injured “the interest of all other orders of men in that country, and of all men in all other countries”.
Enslaved people suffered the most extreme injustice, compelled to create wealth while denied their liberty and the fruits of their labour. Meanwhile, the wider public could bear the costs of a system designed to enrich a privileged minority.
Smith's moral and economic arguments reinforce one another. Slavery violated human liberty, while colonial monopolies demonstrated how political privilege could protect the interests of the few at the expense of society.
The verdict of the impartial spectator is clear: the fact that a system enriches its beneficiaries does not mean that it enriches a nation, still less that it serves the common good.
Mark Griffin