Wenjin Liu

This book argues that Plato’s medical language in political contexts is not mere metaphor but a medical model of political analysis. Centering on the Republic, it shows how Plato adopts, critiques, and reworks Hippocratic ideas to diagnose, explain, evaluate, and treat political conditions. The payoff is a solution to a central puzzle: how the ideal city can be both exceptionally stable and yet liable to degenerate into vice. Its stability, I argue, is a robustness and resilience analogous to bodily health, sustained by protective institutions and practices; its fragility lies in the inevitable fallibility of those protections, which cannot indefinitely prevent, arrest, or reverse corruption over time. On this basis, the Element identifies a corrupt paideia—understood as a city-wide system of acculturation—as the singular, foundational cause of political degeneration, and it closes by drawing lessons about the limits and prospects of genuine reform.

This paper examines Plato’s underexplored conception of civic moderation in the Republic. I argue that civic moderation is the virtue of civic unity. It centrally involves friendship among all citizens, best understood as a communion (κοινωνία) characterized by shared goods, collaboration, coordination, and the proper acknowledgment of one another’s contributions to the joint enterprise of living together in a city. The resulting unity is not that of a single person, as Aristotle and later critics contend, but that of colleagues jointly engaged in a shared undertaking. Civic justice provides the conditions under which civic moderation arises and persists. Along the way, I challenge prevailing thin interpretations that reduce moderation to a shared belief about rule or to the subordination of desires or to a combination of the two, and I argue that the virtue instead comprises two robust and mutually sustaining dimensions: a cognitive network of interrelated commitments about civic life, and affective dispositions of respect, trust, and concern that correspond to those commitments. This account illuminates Plato’s view of psychic unity and his reflections on inter-polis relations.

Despite its centrality in Plato’s Republic, the conception of ignorance has received little sustained attention. This paper argues that Plato distinguishes agnoia—a broad category of cognitive deficiencies—from ignorance (amathia), understood as the vice of the rational part of the soul. Ignorance, on this account, is a particularly pernicious form of agnoia, one that renders reason inept at grasping what is good for human beings. It consists in a network of fundamental yet misguided evaluative commitments about how to live, rooted in an inflated view of one’s own grasp, which distorts reason’s love of truth and wisdom.

Ignorance is commonly assumed to be a lack of knowledge in Plato’s Socratic dialogues. I challenge that assumption. In the Protagoras, ignorance is conceived to be a substantive, structural psychic flaw—the soul’s domination by inferior elements that are by nature fit to be ruled. Ignorant people are characterized by both false beliefs about evaluative matters in specific situations and an enduring deception about their own psychic conditions. On my interpretation, akrasia, moral vices, and epistemic vices are products or forms of ignorance, and a person who lacks knowledge is not necessarily ignorant.