oppp7 said:
If you went back in time, you could kill someone who was already dead (in your time), and arguably not commit a crime. You could also kill someone and travel back in time and refrain from murdering someone. Any crime you commit you could undo or travel to a time when it would not have mattered.
So, do time-machines make morality useless?
I find fault in this argument.
See, if you kill someone in the past, while them being dead in the present, you ARE commiting a crime. Because now you are directly resposible for that person's death at some time, by direct and knowing action on your part leading to his/her death. The past, the present, doesn't matter. Your personal timeline still keeps ticking forward, you still age as normal.
That is still pre-meditated murder.
EDIT: Would it be okay to kill someone today, because tomorrow they would be dead? In retrospect, as you'd wake up tomorrow morning, you could consider the situation to be the same as with your OP. You killed someone in the past and they are dead in the present.
Then to the morality part.
Killing someone and then travelling back in time does not change the fact that you in fact killed the person. Think of it this way: You do a hit-and-run. The person is hopitalized but gets better. Thanks to a super-duper insurance, he pays nothing for the treatments and even get's the salary from the time he cannot work. No important meetings are missed, no harm beyond hospitalization happens to him.
Eventually he fully heals.
No permanent damage was done to the person and the hit-and-run did not cause difficulties for him during recovery.
Yet you still did the hit-and-run. You are still guilty. The effect might no longer be there and it might not have been a negative effect, but you still caused the effect at some point.
Because you haven't removed the action, you have simply moved to a time when the action has yet to take place from anyone elses point of view. You still know you took the action, You still killed a person, before travelling to the past. Your personal timeline has not been rewinded, you have simply displaced it in relation to others timeline.
