| An argument is self-defeating if it supports a defeater for one of its own defeasible steps. |
| A relation of defeasible consequence clearly must be nonmonotonic, since a defeasible inference can be defeated by adding additional information that constitutes a rebutting or undercutting defeater. |
| It is true that awareness of disagreement regarding one's moral endorsements may serve as a defeater. |
| The most prominent of these was Sultan Saladin, the 12th-century defeater of the Crusaders and liberator of Jerusalem. |
| If we have evidence that a subclass of our moral beliefs is not subject to these undercutting defeaters, then that evidence defeats the defeater, and justification is restored. |
| European colonialists started eyeing the airplane as a potential defeater of colonial peoples and enforcer of colonial authority. |
