CRATYLUS

Cratylus (Κρατύλος) was an Athenian philosopher active in the late 5th century BCE, best remembered as a follower of Heraclitus of Ephesus and an early intellectual influence on Plato. His philosophical contributions lie primarily at the intersection of ontology, epistemology, and the philosophy of language.

Taking Heraclitus’ famous doctrine of constant change—that all things are in flux (panta rhei)—Cratylus pushed the theory to its absolute logical extreme. He argued that if everything changes continuously at every instant, then nothing remains stable enough to be known or defined. True knowledge becomes impossible, as any statement about a subject ceases to be accurate the moment it is uttered. According to Aristotle’s account in the Metaphysics, Cratylus eventually concluded that speech itself was impossible and chose instead to communicate merely by moving his finger.

Cratylus is most famous for giving his name to Plato’s dialogue, the Cratylus, which centers on the origin and correctness of names (orthotēs onomatōn). In the dialogue, Cratylus represents the natural correctness view of language. He contends that names are not arbitrary human conventions, but possess an innate, essential connection to the objects they designate, reflecting the intrinsic reality of the thing named.

His radical linguistic realism stands in direct opposition to the conventionalist perspective held by Hermogenes, who argued that names are purely a matter of custom and mutual agreement. Through Socrates, Plato explores this fundamental tension between essentialism and nominalism, examining whether language reveals absolute truths about the universe or merely reflects human agreement.