How Certain Are We That Plato Was Plato?

Socrates, Plato, and Aristotle are regarded as historical figures that shaped philosophy. Socrates taught Plato; Plato founded the Academy and taught Aristotle; and Aristotle later supposedly taught Alexander the Great.

But how can we be certain that these great figures of philosophy actually existed? What physical evidence from their own time actually establishes these individuals, and how was that evidence dated?

This is important because historical repetition does not invoke confirmation, but rather asserts it. If writers throughout the ages repeat the same tradition of acknowledgment, that is not independent confirmation, but rather lineage asserting itself academically. This is not to propose that scientifically dated evidence should be the minimum standard for whether an ancient person existed. Literary testimony, archaeology, inscriptions, paleography, and textual transmission are all forms of historical evidence, but they are not the same evidence.

Socrates appears to have the strongest literary case because Aristophanes placed a character named Socrates in The Clouds, traditionally performed in 423 BCE, while Socrates was supposedly alive, although the surviving text is a later revision. Xenophon and Plato later wrote about him, and the Stanford discussion treats Aristophanes as the earliest surviving literary source. That is meaningful historical evidence. The difficulty of reconstructing the historical Socrates is already well known as the Socratic Problem.