apagoge (n.)

"demonstration of a proposition by the refutation of its opposite, indirect proof, reductio ad absurdum," from Greek apagoge "a leading away" (used by Aristotle in a logical sense), from apagein "to lead away," from assimilated form of apo "from, away from" (see apo-) + agein "push forward, put in motion; stir up; excite, urge," from PIE root *ag- "to drive, draw out or forth, move." Related: Apogogic (1670s); apogogical.