Chris Meyns in The Philosophers' Magazine:
No one is obliged to study any particular topic. But philosophers aren’t stupid. They’re trained to step back, reflect, and should notice when their passion-driven work morphs into a collective omission.
Perhaps there’s simply little to talk about. A lack of source materials. Did philosophers in early modern times even discuss enslavement?
They did. There are some big name philosophers we know and love. John Locke in his Second Treatise of Government (1690) insists that all “men” are naturally in “a state of perfect freedom … [and] equality”, and that no one could sell themselves into slavery for money, even if they wanted to. Some are quick to celebrate anti-slavery pamphlets, such as Montesquieu’s claim in 1748 that “The state of slavery is in its own nature bad”.
There are also less familiar names. Meet Phyllis Wheatley (1753–1784), one of the first African-American published authors, whose poem “On Being Brought from Africa to America” reflects her own experience. Meet Quobna Ottobah Cugoano (1757–ca. 1791), born in present-day Ghana. He survived abduction and forced labour exploitation at the sugar plantations of Grenada. His Thoughts and Sentiments on the Evil and Wicked Traffic of the Slavery and Commerce of the Human Species (1787) refutes point-by-point all attempts of “barbarous inhuman Europeans” to justify slavery. Cugoano argued for a global duty to liberate enslaved people: “Wherefore it is as much the duty of a man who is robbed in that manner to get out of the hands of his enslaver, as it is for any honest community of men to get out of the hands of rogues and villains.” Meet also Olaudah Equiano's (1746–1797), whose The Interesting Narrative and the Life of "Olaudah Equiano" or Gustavus Vassa, the African, published in 1789, presents a host of considerations about enslavement, dignity and empowerment. And meet Doctor of Philosophy, Anton Wilhelm Amo (1703–1759), originally from Axim (in today’s Ghana) and later associated with the German universities of Jena and Halle. Amo published against slavery, in addition to writing on philosophy of mind and philosophical method. Having experienced enslavement first-hand, these philosophers write from a position of epistemic authority.
There is also a ripple of white European women philosophers, who challenge their own subjugated position in society as one of enslavement. “If all men are born free, how is it that all women are born slaves?”, inquires Mary Astell in Some Reflections Upon Marriage (1706). Judith Drake, in An Essay in Defence of the Female Sex (1696), complains that: “Women, like our Negroes in our Western Plantations, are born Slaves, and live Prisoners all their Lives.” These white women appropriated images from African-Caribbean plantation enslavement to lament their own social condition.
More here.