Hamartia

Hamartia is Aristotle's term for the fatal error of tragedy. The word comes from the Greek hamartánein, "to miss the mark" or "to err," and in tragic criticism it "refers to the major defect or inherent weakness of disposition that leads a character to a (potential) downfall." In the Poetics it is the mistake that sets the reversal in motion, and it belongs to a hero of high rank who is neither exceptionally virtuous nor villainous, so the catastrophe reads as cause and effect rather than deserts.

The interpretive fight is old: is hamartia a tragic flaw, a moral defect punished, as neoclassicism read Racine's Phèdre, or a tragic error, a morally neutral mistake born of ignorance? Oedipus, ignorant of his own parentage, is the central example. For writers both readings are engines of a downfall, provided the catastrophe follows from character rather than accident. Hamartia is the classical root of the tragic character arc, and the same Aristotle who required it condemned the deus ex machina: endings must be earned.