When words clash, one side must be false.

Late in the Warring States period, Han Feizi (c. 280–233 BCE), who brought Legalist (法家) thought to its fullest form, told a single parable twice across the fifty-five chapters of the Han Feizi — once in "Nan Yi" and once in "Nan Shi" — as a way of exposing the contradictions of the Confucians. The fable runs as follows. In the state of Chu there was a man who sold both spears and shields (楚人有鬻盾與矛者). First he raised a shield and boasted: "吾盾之堅, 物莫能陷也" — the hardness of my shield is such that nothing can pierce it. Then he raised a spear and boasted again: "吾矛之利, 於物無不陷也" — the sharpness of my spear is such that there is nothing it cannot pierce. At this a bystander asked: "以子之矛, 陷子之盾, 何如?" — what happens if I drive your spear into your shield? The merchant could not answer (其人弗能應也). Han Feizi applied the fable to political argument: "夫不可陷之盾與無不陷之矛, 不可同世而立" — a shield that cannot be pierced and a spear that pierces everything cannot exist in the same world at the same time. He criticized the Confucians for asserting at once both "the virtue (德) of the sage-king" and "the law (法) of the wise man," as the merchant sold spear and shield together. Both claims cannot be true in the same world. From this fable came the two characters 矛盾. And here is the remarkable afterlife of the word: for two thousand years it drifted through the Sinitic world as an occasional term for "things at odds with one another," until, in the late 19th century, Japanese philosophers chose 矛盾 to translate the "contradiction" of Western logic and Hegel's "Widerspruch." From there the coinage was re-imported into China and Korea, until it became the philosophical and logical term across the entire Sinitic sphere. In other words, the modern Korean word "mosun" (矛盾) has come down, character for character, from this very merchant's tale as Han Feizi recorded it.

The English "contradiction" comes from the Latin "contradictio," whose verb is "contradicere." That verb is built from two parts: contra (against, opposed) + dicere (to speak). Translated literally, it means "to speak against, to speak in opposition." In Roman times the verb was used mainly in the practical sense of "raising an opposing view to another's words," in the law courts and in senatorial debate. Cicero treated "contradictio" as a term of rhetoric in his De Oratore. But the word became a central concept of philosophy only afterward. In the 4th century Augustine, in his Confessions, described the inner conflict of the human soul as "contradictio sibi ipsi" (a speaking-against oneself) — and the Latin "sibi ipsi" (to one's own self) maps precisely, in meaning, onto Han Feizi's "自相" (self, mutually). Medieval Scholastic philosophy established the "principium contradictionis" — the law of non-contradiction — as the most basic law of thought. Thomas Aquinas formulated it: "Impossibile est idem simul esse et non esse" — it is impossible for the same thing at the same time both to be and not to be. This is very nearly the same sentence as Han Feizi's "不可同世而立" (cannot stand in the same world at once). The word entered English in the late 14th century by way of the French "contradiction." Writers of Geoffrey Chaucer's era began to use the phrase "self-contradiction." In the 19th century Georg Hegel, in his Science of Logic, made "Widerspruch" (contradiction) the engine of the dialectic, and so the word was reinterpreted beyond a mere logical fault into a "motive force of change." And when late-19th-century Japanese philosophers translated Hegel's Widerspruch into Chinese characters, they chose the 矛盾 of the Han Feizi. The contradictio of Western philosophy and the 矛盾 of the Eastern classic met in that act of translation.