In a number of places chazal describe someone, for our purposes we will dub the 'seer' as seeing the future descendants of certain people, such as Moshe before he killed the Egyptian or Elisha before he caused the bears to kill the youths who were mocking him (Sota 42?). Each time it describes the seer seeing all the future generations and finding them to be without any redeeming merit and then the seer kills the person(s) who's future the he had just seen.
Logically there is something of a paradox here. Since the seer killed the person the future he saw could never have come to be.
What is the nature of those visions the seer saw? Are they possible alternative realities? Projections from God meant just to confirm the seer's decision?