Justice and injustice in the soul are like health and disease in the body; virtue is the health, beauty, and well-being of the soul, vice its disease, and practices causally produce these states.

By Plato, from The Republic

Key Arguments

  • Causal parallel: "that which is healthy causes health, and that which is unhealthy causes disease"; likewise, "just actions cause justice, and unjust actions cause injustice."
  • Order parallel: health is a "natural order and government of one by another in the parts of the body"; justice is the analogous order in the soul; disease and injustice are states at variance with this order.
  • Conclusion: "virtue is the health and beauty and well-being of the soul, and vice the disease and weakness and deformity of the same," and habits—"good practices" vs "evil practices"—lead to each.

Source Quotes

What do you mean? he said. Why, I said, they are like disease and health; being in the soul just what disease and health are in the body. How so? he said.
How so? he said. Why, I said, that which is healthy causes health, and that which is unhealthy causes disease. Yes.
Yes. And just actions cause justice, and unjust actions cause injustice? That is certain.
That is certain. And the creation of health is the institution of a natural order and government of one by another in the parts of the body; and the creation of disease is the production of a state of things at variance with this natural order? True.
True. And is not the creation of justice the institution of a natural order and government of one by another in the parts of the soul, and the creation of injustice the production of a state of things at variance with the natural order? Exactly so, he said.
Exactly so, he said. Then virtue is the health and beauty and well-being of the soul, and vice the disease and weakness and deformity of the same? True.
True. And do not good practices lead to virtue, and evil practices to vice? Assuredly.

Key Concepts

  • they are like disease and health; being in the soul just what disease and health are in the body.
  • that which is healthy causes health, and that which is unhealthy causes disease.
  • And just actions cause justice, and unjust actions cause injustice?
  • the creation of health is the institution of a natural order and government of one by another in the parts of the body
  • the creation of justice the institution of a natural order and government of one by another in the parts of the soul
  • Then virtue is the health and beauty and well-being of the soul, and vice the disease and weakness and deformity of the same?
  • And do not good practices lead to virtue, and evil practices to vice?

Context

Socrates consolidates the definitions of justice and injustice by introducing a sustained medical analogy to explain their nature, causes, and normative valence.

Perspectives

Plato
Approves the medical model as illuminating the Form-like order of the soul; virtue is a structural harmony, cultivated by habituation in accord with reason.
Socrates
Uses familiar bodily health to clarify why just practices intrinsically benefit the soul, while unjust ones produce psychic pathology.