| One use of modus tollens is the reductio ad absurdum argument, i.e. showing that a premise is false by demonstrating that it implies an absurd conclusion. |
| Opposition to stem-cell research is the reductio ad absurdum of the right-to-life argument. |
| It would be only fitting, the reductio ad absurdum of our divided age, for this election to take two extra months. |
| It's an entertaining reductio ad absurdum against those who complain about the unfairness of low-cost production by foreigners. |
| The French geometer, Legendre, gave a rigorous proof by reductio ad absurdum. |
| The method of exhaustion used, for the purpose of proof by reductio ad absurdum, the lemma proved in Eucl. |
