Would It Be Wrong to Build a Time Machine?

Happy Back to the Future Day! October 21, 2015 is the day that Marty McFly travelled to the future in Doc Brown’s time-traveling DeLorean. To commemorate this day, I thought we should have a bit of fun and consider an interesting (and hypothetical) moral question.

Suppose we could build a time machine. Would it be wrong to build one?

Let’s start by discussing two considerations concerning the ethics of time travel that often pop up in time travel movies. Sometimes people in time travel movies think it’s obviously okay to build a time machine. However, sometimes people in time travel movies think it’s obviously wrong. Let’s consider each reason in turn.

1. You could prevent the Holocaust
One tempting reason to create a time machine would be that you could go back and thwart awful things that happened. Perhaps you could assassinate Hitler before he rose to power and thus prevent the Holocaust. The problem here is that if time travel is possible, then the things that are true about the past have already happened. This includes any attempts you’ve made to go back and change history. So, if you’re given an opportunity to go back and prevent the Holocaust, you’re guaranteed to fail. Whatever you try to do, you’ve already tried and the end result was, unfortunately, no different than what was already true about the past before you traveled back in time.

2. You might undo the fabric of the universe
On the other side, some might argue that time travel is too risky. You might, for example, go back and make something true that wasn’t originally true. Who knows what that contradiction might do. Perhaps you’ll implode all of space-time. This should be a reason against developing a time travel machine for precisely the same reason that preventing the Holocaust is a reason to create one. The problem here is the same as the problem above. You can’t go back and make a contradiction true. Anything you go back and do will be the way the past always was. You’re destined to do anything you go back to do (if you become a time traveler).

Those are the kinds of things people typically say about the ethics of time travel in the movies, but neither are persuasive. However, even if you can’t change the past so that history takes a different turn, time travel is not something that would be completely boring. You could still go back in time and do things in the past. They would just be things that had already happened in your past, so you won’t change things from the way they already are. So, it’s still worth considering whether or not it’s something we should or shouldn’t do.

3. Taking unfair advantage of the past
If time travel is possible, you could still go back and exploit the past. You could use your knowledge of the gold rush and go back and extract gold and bring it back to the present. We know you won’t be able to set up a mining operation and take ALL the gold. The gold rush happened, so if you tried – you’d fail. But you could take enough before everyone else found out to make yourself rich here and now. But this points to ways in which you have a potentially unfair advantage over people from the past. One might worry that there is something wrong with extracting resources that aren’t from your time.

4. Privacy violations
Time travellers would pose an interesting threat to privacy. We’ve gathered an enormous amount of information about people from the past, and in many cases this information was made public about the person (long after they died). We never really worried about this as a potential privacy threat, because it was thought that this information could no longer be used to harm them. However, that’s not true if time travel ever becomes a reality.

5. History class would be amazing
Even if you couldn’t change the past, you could learn a TON about the past. History could become something like covert Sociology or Anthropology. Knowledge about important historical events would be incredibly valuable. Don’t worry about changing the course of history. If you go back in time to observe history, you were already there.

6. You could still do enormous good
Even if you go back in time and can’t make horrible events disappear, it still might be the case that those horrible events are less bad because you went back to try and prevent them. You could go back and participate in any humanitarian events that you thought were worthwhile. If time travel were ever to become a reality, then it might be that some bad events are not as bad as they could have been because of the failed efforts of time travellers to fully prevent them. If time travel ever became possible, then it will be within the realm of possibilities that any bad event in our past was made less bad by time travellers.

So, the end result is a bit mixed. I don’t think it would be obligatory to make a time machine, because I don’t think you could prevent things that we already know have happened. I don’t think it would be obviously wrong to make a time machine, because I don’t think you would risk undermining the fabric of the universe. If time travel ever became a reality it would open up exciting options for doing good, but also options for doing evil. You could do enormous good in the past, and benefit yourself here in the future. But you could also do some pretty bad things too. So, I think the moral dilemma here isn’t all that much different than the moral dilemmas we encounter with most emergent technology.