The vast majority of us have no inclination to kill anyone, much less a small child. But what if we had the chance to kill baby Adolf Hitler, preventing the Holocaust and indeed the Second World War? That hypothetical question has endured for a variety of reasons, touching as it does on the concepts of genocide and infant murder in forms even more highly charged than usual. It also presents, in the words of Time Travel: A History author James Gleick, "two problems at once. There's a scientific problem — you can set your mind to work imagining, 'Could such a thing be possible and how would that work?' And then there's an ethical problem. 'If I could, would I, should I?'"
By the simplest analysis, writes Vox's Dylan Matthews, the question comes down to, "Is it ethical to kill one person to save 40-plus million people?" But time-travel fiction has been around long enough that we've all internalized the message that it's not quite so simple. We can even question the assumption that killing baby Hitler would prevent the Holocaust and World War II in the first place.
Maybe those terrible events happen on any timeline, regardless of whether Hitler lives or dies: that would align with the Novikov self-consistency principle, which holds that "time travel could be possible, but must be consistent with the past as it has already taken place," and which has been dramatized in time-travel stories from La Jetée to The Terminator.
Gleick doesn't have a straight answer in the Vox video on the killing-baby-hitler question above as to whether he himself would go back to 1889 and put baby Hitler out of action. "When you change history," he says of the moral of the countless many time travel stories he's read, "you don't get the result you're looking for. Every day, everything we do is a turning point in history, whether it's obvious to us or not." This in contrast to former Florida governor and United States presidential candidate Jeb Bush, who, when he had the big baby-Hitler question put to him by the Huffington Post, returned a hearty "Hell yea I would." But given time to reflect, even he concluded that such an act "could have a dangerous effect on everything else." It appears that some of the lessons of time-travel stories have been learned, but as for what humanity will do if it actually develops time-travel technology — maybe we'd rather not peer into the future to find out.
Based in Seoul, Colin Marshall writes and broadcasts on cities, language, and culture. His projects include the book The Stateless City: a Walk through 21st-Century Los Angeles and the video series The City in Cinema. Follow him on Twitter at @colinmarshall, on Facebook, or on Instagram.