Socratic trustworthiness depends upon devices of irony, both spoken and acted. … The irony of words prevents Socrates from being taken as the source of doctrines. The irony of actions prevents Socrates from being made into the literal founder of a philosophic school. … The ironic voice does not seek to possess the student, but directs him, lustlessly, to the desire of philosophy itself.

Authority and persuasion in philosophy (1985)