reductio ad absurdum

plural reductio ad absurdums

1. uncountableusuallyhuman sciencesThe method of disproving a statement by assuming the statement is true and, with that assumption, arriving at a blatant contradiction.

   “You, gentlemen, as representatives of that institution which recognizes only truths that are deduced from reductio ad absurdums will probably have no difficulty in perceiving the truth of this absurdity and hence be ready to excuse the outcome of it—my absence.”

   1894, Flora Helm, “Concerns a Talk in Which Anarchy and Love Are Blended”, in Between Two Forces: A Record of a Theory and a Passion, Boston, Mass.: Arena Publishing Company. […], pages 149–150

   2 more examples

   Constructing representations out of atoms that are already themselves representations cannot address the origins of the atoms per se. Careful pursuit of such approaches has yielded bizarre reductio ad absurdums such as the implication that virtually all concepts that human beings are capable of having are already in the genes.

   1998, Mark H. Bickhard, “Constructivisms and Relativisms: A Shopper’s Guide”, in Michael R[obert] Matthews, editor, Constructivism in Science Education: A Philosophical Examination, Dordrecht; Boston, Mass.; London: Kluwer Academic Publishers, →ISBN, page 106

   One way to argue against a position is to demonstrate that it proves too much. Proponents of an HWR analysis of negligence may insist that the conceptual and normative arguments that have been directed against their project ultimately generate reductio ad absurdums suggesting that I have proved too much.

   2009, Michael S. Moore, “Normative Problems in Applying the Harm-within-the-Risk Test to Crimes/Torts of Negligence”, in Causation and Responsibility: An Essay in Law, Morals, and Metaphysics, Oxford University Press, published 2010, →ISBN, section III (The First Blind Alley: The Attempt to Replace Proximate Causation with Culpability as a Prerequisite for Legal Liability), page 208

   Synonyms: apagoge, proof by contradiction, reduction to the absurd