from The American Heritage® Dictionary of the English Language, 4th Edition
- n. Disproof of a proposition by showing that it leads to absurd or untenable conclusions.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. The method of proving a statement by assuming the statement is false and, with that assumption, arriving at a blatant contradiction.
from The Century Dictionary and Cyclopedia
- n. A reduction to an absurdity; the proof of a proposition by proving tho falsity of its contradictory opposite: an indirect demonstration.
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- n. (reduction to the absurd) a disproof by showing that the consequences of the proposition are absurd; or a proof of a proposition by showing that its negation leads to a contradiction
Historic Doubts relative to Napoleon Buonaparte (1819), intended as a reductio ad absurdum of Hume’s contention that no evidence is sufficient to prove a miracle,
In St. Anselm's own day this argument was objected to by Gaunilo, who maintained as a reductio ad absurdum that were it valid one could prove by means of it the actual existence somewhere of an ideal island far surpassing in riches and delights the fabled Isles of the Blessed.
The reconstitution of this particular dream illustrates the reductio ad absurdum of the two previous psycho-analytic "solutions."