Vom Geist der Gesetze
Montesquieu advocated reform of slavery in "The Spirit of the Laws," specifically arguing that slavery was inherently wrong because all humans are born equal, but that it could perhaps be justified within the context of climates with intense heat, wherein laborers would feel less inclined to work voluntarily. As part of his advocacy he presented a satirical hypothetical list of arguments for slavery. In the hypothetical list, he'd ironically list pro-slavery arguments without further comment, including an argument stating that sugar would become too expensive without the free labor of slaves.