In the context of slavery, science is usually associated with slaveholders' scientific justifications of racism. But this book demonstrates that abolitionists were equally adept at using scientific ideas to discredit slaveholders. Focusing on antislavery scientists and black and white abolitionists in Britain and America between the 1770s and 1860s, historian Eric Herschthal shows how these activists drew upon chemistry, botany, medicine, and mechanics to portray slavery as a premodern institution bound for obsolescence. These activists contended that slavery stood in the way of scientific progress, blinded slaveholders to scientific evidence, and prevented enslavers from adopting labor-saving technologies that might eradicate enslaved labor. Historians have recently begun to challenge the myth that slavery was premodern--backward--demonstrating slavery's centrality to the rise of modern capitalism, science, and technology. This book demonstrates where the myth comes from in the first place.