A song of Ice and fire discussion (spoilers incl A Dance with Dragons)

['thul]

Magic is rather uncertain. It might keep to the exact wording of the oath, which means that the wall should have fallen long ago, or it might keep to the spirit of the oath. If the guardians of the wall, the night's watch, stop guarding altogether against the threat of the white walkers, then the magic might fail. It could just as well be that so long as the intent of the watch as an entity is still to guard the realms of man against the white walkers, then the magic will live. The magic cannot be all that fickle, for the wills of man change all the time. There will always be LCs that don't care enough about the task. It might be that many a LC has thought the task is mostly guarding realms of man against wildlings, but because the intent is still to guard the realms of man, then the magic persisted.
The magic would probably fail if the LC and most of the watch, if not the entire watch, stopped caring about guarding the realms of man at all. If they were to instead be turncloaks and not guarding realms of man at all, then the wall would effectively have failed anyways. it might be thick, it might be tall, but so long as there are none to stop climbers, it is merely an obstacle.