| But prima facie permanence of obligations does, like all prima facie statements imply defeasibility. |
| The third feature of rational reasons is their defeasibility. |
| In the MMR case, however, people do not want to hear about defeasibility and inductive probability. |
| See also Makinson 1993 for a sweeping discussion of defeasibility and the place of deontic conditionals in this context. |
| Smith 1994 contains an interesting informal discussion of conflicting obligations, defeasibility, violability and contrary-to-duty conditionals. |
| However, this is just the inevitable defeasibility of any form of inference that depends on background empirical presuppositions. |
