Killing someones grandparents
During a rather boring english lesson, a friend of mine decided he wanted to kill me :(. His plan was to go back in time, and kill my grandparents so that I would never exist. He's an idiot so I didn't pay much attention to what he said anyway.
But I got to thinking, would that be possible? If he killed my gradparents, I would never be born. So if I was never born, he would never have met me. If he never met me, he would have no reason to go back in time to kill my grandparents. If he never killed them, they they would exist again and so would I.
How does that sound? I guess its a lot like the grandfather theory, where you can't kill your own grandparents because you would not exist, and so would never come back to kill them. The only difference is its someone else doing the killing. With me not existing, he has no reason to go back in time, and so I would exist again.
Does what I said make sense? Would it then be impossible to go back in time (if we assume time travel IS possible) and kill someone? Then wouldn't it be impossible to kill hitler and not have world war II, because if he didn't exist you would have no reason to go back, and so then he would?