As the idea of liberty spread, slavery and serfdom came under attack throughout the Western world. During the British debate over the idea of compensating slaveholders for the loss of their “property,” the libertarian Benjamin Pearson replied that he had “thought it was the slaves who should have been compensated.”

In the United States, the abolitionist movement was naturally led by libertarians. Leading abolitionists called slavery “man stealing,” in that it sought to deny self‐​ownership and steal a man’s very self. Their arguments paralleled those of John Locke and the libertarian agitators known as the Levellers. William Lloyd Garrison wrote that his goal was not just the abolition of slavery but “the emancipation of our whole race from the dominion of man, from the thraldom of self, from the government of brute force.”

Frederick Douglass likewise made his arguments for abolition in the terms of classical liberalism and libertarianism: self‐​ownership and natural rights. After the Civil War, he continued his fight for equal freedom, campaigning against Southern states’ efforts to avoid following the new constitutional amendments. And he applied his belief in liberty and equal rights universally: He backed women’s suffrage, saying “we hold woman to be justly entitled to all we claim for man.” He defended Chinese immigrants, pointing out that there are “no rights of race superior to the rights of humanity.” In Great Britain he joined campaigns for free trade and Irish freedom.

Just as a better understanding of natural rights was developed during the American struggle against specific injustices suffered by the colonies, the feminist and abolitionist Angelina Grimké noted in an 1837 letter, “I have found the Anti‐​Slavery cause to be the high school of morals in our land — the school in which human rights are more fully investigated, and better understood and taught, than in any other.”

Racism is an age‐​old problem, but it clearly clashes with the universal ethics of libertarianism and the equal natural rights of all men and women. As Ayn Rand pointed out in her 1963 essay “Racism,”