NPR lays out the scenario:
You find a time machine and travel to 1920. A young Austrian artist and war veteran named Adolf Hitler is staying in the hotel room next to yours. The doors aren't locked, so you could easily stroll next door and smother him. World War II would never happen.
But Hitler hasn't done anything wrong yet. Is it acceptable to kill him to prevent World War II?
Leaving aside the highly dubious notion that World War II could be prevented with such a simple act or that the results would be more favorable than World War II as it unfolded in real history, you have a moral dilemma.
Rebecca Friesdorf, a graduate student at Wilfrid Laurier University in Ontario examined how people respond to this and other moral dilemmas and their reasoning for their choices. She surveyed 6,100 people from the USA, Canada, and Germany. Friesdorf published the results of her study in the Personality and Social Psychology Bulletin.
Friesdorf found that women were less likely to kill Hitler when given the chance. Ben Tufft writes in The Independent:
While men and women both calculated the consequences of their decision and computed how many lives might be saved, females found it harder to commit murder and were more likely to let Hitler live.
-via David Burge
If pressed, Jrxlsnikt defines "evil" as something or someone (it could be a creature, after all) who's actions result in apocalypse-level loss of life. We're talking a significant portion of the population destroyed due to the actions of this one being. Somehow, however improbable it seems, you are able to defeat it *maybe it's allergic to plastic and plastic doesn't exist in Jrxlsnikt's realm?).
Yes, the trolley problem is relevant, but only if you feel that the individual labelled here as "evil" is equally valuable as a life as the countless lives that would be lost if it goes on it's rampage. The trolley problem fails for me, in that 5 lives vs 1 just doesn't hit home. 1 life vs apocalypse... now I'm paying attention.
Time travelling involves the big problems, including completely leveraging causality.... So i tried to avoid this field by stating that you have knowledge of future events (which could include clairvoyance etc.).
Your scenario includes many unaswered qeustions. ... "Evil" is a very elastic concept. Additionally, i usually don't consider "slewing" as a good solution. rendering the situation may be covered by the trolley problem:
http://en.wikipedia.org/wiki/Trolley_problem
Actually, it seems the Jrxlsnikt once managed to talk me into this mission... therefore i have to expect he will manage it once again... so presumably the answer would be "yes".
Presumably i would actually go, not so for the sake of evil slaying, heorism, life saving or the other important stuff... but having an oppotinity to travel back in time and / or into another dimension would be too appealing for me so i would popably not be capable of rejecting this offer.
Any survey question about time travel that doesn't address this issue is basically pointless.
Here's my version of the survey question that side-steps the grandfather paradox:
"A time traveler arrives at your door and introduces themselves as Jrxlsnikt. After thorouhly proving that they are, in fact, a time traveler and not a nutter, they explain the following:
1. They are from another world, another dimension, another timeline separate from yours.
2. In their timeline, it is recorded that they (the time traveler) arrived in their own time period alongside a stranger from another dimension (you) and slew a great evil just as it was beginning to emerge.
3. It is known from previous times that, when this evil emerges, many millions of lives would be lost.
The time traveler asks if you would follow them back to the past of their world and fulfill the mission that is recorded in their history. They assure you that you are fully capable of carrying it out.
Do you go?"