In "Meno," Socrates and Meno set out to find teachers of ethics. When they are unable to find any, the reader is left wondering if knowledge, goodness, and justness can be taught.

"Parmenides" tells of the meeting between a young Socrates and two philosophers from the Eleatic school, Parmenides and Zeno. In his most challenging work of philosophy, Plato debates monism and plurality.

In "Theaetetus," Socrates and Theaetetus explore the three definitions of knowledge: knowledge as perception, knowledge as true judgment, and knowledge as a judgment with an account. All three definitions prove to be inadequate.