apagoge

apagoge

(ˌæpəˈɡəʊdʒɪ)
n
an indirect argument which serves to prove something by showing the contrary to be absurd or impossible

apagoge

a method of argument in which the proposition to be established is emphasized through the disproving of its contradiction; reductio ad absurdum.apagogic, adj.
See also: Argumentation