Drapetomania, the Slave Disease

When the first slave ship landed in America in 1619, slavery was accepted as legal for the next 246 years up until the 13th Amendment's ratification. Slaves were not treated as human beings at the time, but that didn't stop certain backward-thinking doctors from treating them as such and then acting as though they were flawed in some manner when they refused to become slaves. This was mostly Samuel A. Cartwright's creation.

Being a doctor, Cartwright assumed that any slave who attempted to escape bondage must have been suffering from an illness. He termed it drapetomania, and slave owners might cure it by beating their captives or amputating their toes.

By today's standards, Cartwright's efforts to use science to support slavery were shockingly irrational. According to his medical theory, slaves had little brains and underdeveloped nerve systems, making it impossible for them to be happy unless they were also slaves. All of this contributed to the lie that slave owners propagated, claiming that their position was advantageous to the slaves and that they were essentially doing them a favor.