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PlatoTheaetetus
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Key Figures
Plato
Plato (427-347 BCEE) was an Athenian philosopher in Ancient Greece and the author of Theaetetus. A student of Socrates, Plato also founded the first academy in the Western world, a forerunner to the modern university, in Athens. Its most famous member, a student of Plato, was Aristotle (384-322 BCE). How much of Theaetetus represents Socrates’s views and how much represents Plato’s is hard to establish, as Socrates did not preserve his philosophy in written form. Nevertheless, Plato’s influence on Western thought and philosophy has been huge. His writings, via Neoplatonism, were critical in the development and codification of Christianity and the early Christian church. He is also credited with founding Western political philosophy through his work Republic.
His other major works, all of which are in dialogue form, and most of which feature Socrates as the principal character, include Symposium (385 BCE), Republic (375 BCE), and Phaedrus (370 BCE).
Socrates
Socrates (470-399 BCE) was an Ancient Greek philosopher, the teacher of Plato, and the main protagonist of Theaetetus. As he produced no written texts, our ideas about who he was, and what he said and thought, come from others, principally Plato via his Socratic dialogues. However, other Greeks, such as his students Xenophon and Antisthenes, and playwright Aristophanes, also wrote about him.
In the Western world he is perhaps best known for his founding role in moral philosophy, and for embodying the ideal of philosophical wisdom and virtue. This status was partly cemented by his death; after being put on trial for impiety and “corrupting the youth,” Socrates was obliged to commit suicide by drinking hemlock. Despite his legendary status and influence on Western philosophy, not all philosophers have seen him as unambiguously positive. Most notably, Friedrich Nietzsche (1844-1900) criticizes him in The Birth of Tragedy (1872) for overvaluing rationality and contributing to the demise of Ancient Greek tragedy. Socrates is also known as the founder of the Socratic or elenctic method, a mode of philosophical enquiry based on cooperative dialogue and the back-and-forth posing of questions and answers.
Theaetetus
Theaetetus (417-369 BCE) was an Athenian mathematician and friend of Socrates and Plato. He is Socrates’s dialogic partner in Theaetetus, the Socratic dialogue by Plato that bears his name. At the time of the dialogue, Theaetetus is a young geometry student. Although he does suggest some original ideas, he mainly serves as a sounding board for Socrates, as a way for the latter to explore and refute various ideas about knowledge. Theaetetus is believed to have died of dysentery while returning from a battle at Corinth in 369 BCE, an event partially referenced in Theaetetus.
Protagoras
Protagoras (490-420 BCEE) was a pre-Socratic Ancient Greek philosopher and sophist. He is most famous for his statement, “Man is the measure of all things,” and for his relativistic conception of truth. In Theaetetus Protagoras is held up as Socrates’s principal philosophical foil and as the defender of the perceptual theory of knowledge, which holds that knowledge is perception. However, it is unclear how accurately Protagoras’s thought is represented here. He authored several works, including Truth, referred to in Theaetetus. Plato writes about him at more length in the dialogue Protagoras.
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