Dialogues · Chapter
Theaetetus explained
Socrates engages in a dialectical inquiry with the young mathematician Theaetetus, exploring the nature of knowledge.
What happens
Socrates engages in a dialectical inquiry with the young mathematician Theaetetus, exploring the nature of knowledge. They consider and refute definitions of knowledge as perception, true judgment, and true judgment with an account, ultimately concluding that knowledge is not fully defined in the dialogue.
Themes in this chapter
Knowledge and Ignorance
The central theme of the dialogue, as Socrates and Theaetetus attempt to define knowledge and distinguish it from perception and true belief.
Education and Virtue
The dialogue exemplifies Socratic education through dialectic, aiming to cultivate intellectual virtue by exposing ignorance.
Characters to notice
- Socrates
Leads the inquiry into the definition of knowledge, questioning Theaetetus and guiding the dialectic.
- Theaetetus
The young mathematician who proposes and defends various definitions of knowledge.
- Theodorus
The geometrician who introduces Theaetetus to Socrates and participates in the early discussion.
- Euclid
Mentioned as the one who recorded the dialogue from Socrates' narration.
- Terpsion
Present with Euclid at the opening of the dialogue, listening to the reading of the record.
Key passages
“Knowledge is nothing but perception.”
Theaetetus first proposes that knowledge is identical to sense perception, but Socrates refutes this by showing that perception is relative and not infallible.
This is the first definition of knowledge examined in the dialogue.
“Knowledge is true judgment.”
Theaetetus then suggests that knowledge is true belief, but Socrates argues that true judgment can be mistaken without an account, so it is insufficient.
This is the second definition, which is also refuted.
“Knowledge is true judgment with an account.”
Theaetetus offers a third definition, that knowledge requires justification, but Socrates shows that an account can be circular or incomplete, leaving the definition unresolved.
The dialogue ends in aporia, with no final definition achieved.