For more than a decade, activists, scholars, journalists, and politicians of various stripes have been discussing and decrying mass incarceration. This collection of voices has mostly focused on contingent features of the phenomenon. Critics mention racial disparities, poor prison conditions, and spiraling costs. Some critics have alleged broader problems: they have called for an end to all incarceration, even all punishment. Lost in this conversation is a focus on what is inherently wrong with mass incarceration specifically. This essay fills that void and supplies an answer, drawing on the early modern English philosopher Thomas Hobbes. On the Hobbesian account developed here, mass incarceration is always wrong because it is always inconsistent with having a free society.