section_path: Philosophy/Virtue and knowledge
section_name: Virtue and knowledge
paragraph_text: Virtue and knowledge
  
  Socrates's theory of virtue states that all virtues are essentially one, since they are a form of knowledge. For Socrates, the reason a person is not good is because they lack knowledge. Since knowledge is united, virtues are united as well. Another famous dictum—"no one errs willingly"—also derives from this theory. In Protagoras, Socrates argues for the unity of virtues using the example of courage: if someone knows what the relevant danger is, they can undertake a risk. Aristotle comments: "... Socrates the elder thought that the end of life was knowledge of virtue, and he used to seek for the definition of justice, courage, and each of the parts of virtue, and this was a reasonable approach, since he thought that all virtues were sciences, and that as soon as one knew justice, he would be just..."