[Tokzic]

Originally Posted by devonin

In order for this to make any sense, we have to assume a situation where the present is say, 2021.

I actually said in my example that you decide to go back in time the next day, but okay, I'll roll with this if you'd prefer it that way.

Originally Posted by devonin

The simple answer is, if in 2021, Bob has been killed, and it isn't until 2021 that you decide to go back in time to save him, then your 2021 self failed to stop the assassin. I can concieve of any number of reasons why you would fail. Perhaps you tried to stop him and he simply bested you before going on to kill Bob, perhaps you decided the potential risk to the timeline was too great and stopped, perhaps you were stopped by some sort of time police from further up your timeline, perhaps as in the case of a great Red Dwarf episode, you stop the assassin, and then realise that the results would have been worse than Dead Bob and carry out the killing yourself. Regardless, the fact that your 2020 necessarily included your 2021 self trying to stop the killer, and yet your 2020 also includes Bob dead, your 2021 self either failed or didn't try.

This doesn't have anything to do with my post. My question isn't addressing what happens if Bob dies, but if Bob lives. If your 2021 self succeeds, Bob lives in 2020; but then you have no indication that you need to go back in time in 2021. Thus, you will not stop the assassin, and thus he dies. But he can't die, or else the timeline would change. So is it just impossible, or do you get the sudden premonition (well, "postmonition", but you know what I mean) that Bob will die unless you go back in time and save him?