1580s, earlier dialatik (late 14c.), "critical examination of the truth of an opinion, formal reason and logic applied to rhetoric and refutation," from Old French dialectique (12c.) and directly from Latin dialectica, from Greek dialektike (techne) "(art of) philosophical discussion or discourse," fem. of dialektikos "of conversation, discourse," from dialektos "discourse, conversation" (see dialect).
Originally synonymous with logic; in modern philosophy refined by Kant ("the theory of false argumentation leading to contradictions and fallacies), then by Hegel, who made it mean "process of resolving or merging contradictions in character to attain higher truths." Used generally in 20c. Marxism for "evolution by means of contradictions." Related: Dialectics.