The romans enslaved people, enforced a rigid patriarchy, and delighted in the spectacle of prisoners being tortured at the Colosseum. Top minds of the ancient Western world—luminaries such as Aristotle, whose works are still taught in undergraduate lectures today—defended slavery as an entirely natural and proper practice. Indeed, from the dawn of the agricultural era to the 19th century, slavery was ubiquitous across the world. It’s hard to understand how our predecessors could have been so horrifically wrong.
We have made real progress since then. Though still very far from perfect, society is in many respects considerably more humane and just than it once was. But why should anyone think this journey of moral progress is close to complete? Given humanity’s track record, we almost certainly are, like our forebears, committing grave moral mistakes at this very moment. When future generations look back on us, they might see us like we see the Romans. Contemplating our potential moral wrongdoing is a challenging exercise: It requires us to perceive and scrutinize everything that humanity does.