EN
The paper deals with the way how Plato uses the phrase doing one’s own in searching for the definition of sôphrosunê in the Charmides. Although the main theme of this dialogue is sôphrosunê, the consequence of the Critias’ concept of sôphrosunê, namely that sôphrosunê does not bring the community any advantage, also concerns the benefit of the community. The paper deals with the aporia of possibility and usefulness of self-knowledge in the dialogue. The text intends to show that the source of these aporia is Critias’ strict separation of three kinds of knowledge (“the knowledge of knowledge”, the “knowledge of good and evil” and “technical knowledge”). This separation is based on Critias’ potentially tyrannical “self-consciousness“ freed from all content determinations and governing the knowledge of good and evil. The unity between them has to the form of a complex structure the bearer of which is the soul and which is dominated by the knowledge of good and evil.