elenchus

noun, plural e·len·chi [ih-leng-kahy, -kee] /ɪˈlɛŋ kaɪ, -ki/.

1. a logical refutation; an argument that refutes another argument by proving the contrary of its conclusion.

noun plural -chi (-kaɪ) logic

1. refutation of an argument by proving the contrary of its conclusion, esp syllogistically
2. Socratic elenchus the drawing out of the consequences of a position in order to show them to be contrary to some accepted position