After the recent post about time travel, some readers wondered about the morality of interacting with the past and whether we would be obliged to refrain from changing historical events or not. In other words, would we be bound by a "temporal prime directive" against interfering with history if we travelled into the past.
This is actually something I’ve thought about, so here are some reflections.
The fundamental moral axiom is "Do good and avoid evil." This axiom is binding on all people, all the time. It is part of human nature. If we were transported into the past it would be binding on us then. We would have to do our best to do good and avoid evil, just as we are bound to do it now.
The question is whether interfering with history is a good or an evil–and whether it is even possible.
As sci-fi writers, among others, have speculated, changing history may not be possible. It may be, for example, that if we end up in the past then this does not represent a change to history. We were always part of history, and so whatever actions we take in the past played their proper role in how history did unfold.
If this is the case then three things follow: (1) We can’t change history because our introduction into it was always there, and it will unfold exactly as it did in our timeline and (2) we therefore don’t have to worry about whether we’re changing history. We can just do our best to do good and avoid evil. Also (3) we can avoid wasting our time trying to prevent outcomes that we already know (e.g., we may as well not try to stop 9/11 from happening). The issue of a temporal prime directive thus fails to arise if this is how time travel works.
There is also another version of how history is unchangeable. It could be that we were NOT part of history the "first time" it unfolded, and our insertion into the past OF ITSELF represents a change. It would appear, if this is how things work, that arriving in the past of itself creates an alternate timeline–one that is different than the timeline in which we originated.
But if that’s the case then, no matter what we do in the alterate timeline, we aren’t really changing history–not OUR history. That’s back on the original timeline that we left. The new timeline that we’re living in is one that budded off of ours.
If that’s the case then we are under no obligation to protect our own history because we have no ability to affect that history. That’s a timeline we are no longer part of.
It might be possible (depending on how time travel works) to get back to that timeline, but that would mean leaving the alterate timeline (no matter what good or bad we’ve done in it) and getting back to our original reality, in which we never appeared in history. If this is the case then visiting the past is like visiting an alterate universe. No matter what we do there, we won’t have to live with the effects of it once we return to our own home timeline.
So while in the "past" (really an alterate past) we would have the liberty to do good and avoid evil to the best of our ability. Stop 9/11? Sure! It’ll help the folks out who live in that timeline, even if our 9/11 will still be there when we return to our own timeline.
On the other hand, it may not be possible to get back to our own timeline. If we jump forward into the future, we may be jumping into the future of the alterate timeline that was created by our insertion into the past. In that case, we’ll have to live with the effects of what we’ve done. That’s an added incentive to be careful about what we do, since we’re now personally invested in the future of this timeline, but it doesn’t affect the fundamental moral calculus of how we should behave in it. Even if we weren’t going to stay in this timeline, the Golden Rule would tell us "Don’t mess up someone else’s timeline if you wouldn’t want someone else to mess up yours."
Since, on this option, we’re not really changing our own timeline, the issue of a temporal prime directive does not arise–at least not directly.
Of course, we could get scrupulous about the effects out actions will have on the timeline. Perhaps all kinds of "Monkey’s Paw" situations will arise and by trying to fix problems, we’ll actually make them worse.
Could be.
But that’s something we have to live with all the time back home in our original reality. We don’t know what the ultimate effects of our actions are going to be. We just have to do our best, based on the knowledge we have at the moment, to do good and avoid evil. If we’re in an alterate timeline but have an idea where it’s going to go based on the way our timeline did then that’s a bit of extra knowledge for us, but we can’t start out by second-guessing ourselves to death, worrying excessively about whether we’re helping or harming. We have to just do the best we can with the info we’ve got.
(And if we don’t like the results, we can jump back into the "past" again and bud off a new timeline where we can try to do things better. This, however, isn’t really fixing the existing timeline; it’s just transferring us to a new timeline where we hopefully won’t make the same mistakes.)
At this point we don’t have any experience with changing the "past," so we don’t really know whether attempting to do so generally produes good or bad (or neutral) results. It could turn out that attempts to change major historical events invariably makes things worse, but at this point we don’t have evidence for that. If evidence started accumulating then instituting a temporal prime directive of some kind would make sense, but imposing one up front would not make sense.
The mere fact of us being in the past when we weren’t originally means that some changes are made to history, and once we’re there we can’t avoid affecting things–just breathing and taking up space does that. So we may as well not second guess our ability to help the new timeline that we’re in until we get solid evidence that such attempts are more harmful than helpful.
(NOTE: God could have a "Please don’t mess with history" rule, but since he didn’t put it in the deposit of faith in our timeline means that we would likely only figure it out by experience. However, the very fact that he lets us go into the "past" when we weren’t originally there is an indication that he doesn’t mind us working to improve alternate timelines.)
On both of the two theories I’ve just sketched out, changing history isn’t really possible: in the first case because we were always part of history and in the second case because we are in an alterate timeline and not our own.
But is there a third possibility?
Could we really go back into OUR history when we weren’t there originally and change things?
I don’t think so. If we weren’t in history originally and then we put ourselves there then it seems to me that it’s no longer OUR history. It’s a new history–an alterate timeline. That seems to be true by definition.
And, as always happen when you try thought experiments that involve breaking things that are true by definition, you get paradoxes.
Thus if you suppose that we can inject ourselves into a history that we weren’t originally part of, you get things like the Grandfather Paradox. Since I don’t think that physical paradoxes can exist in actuality, I don’t think that this kind of time travel is possible.
There are other ways conceptualizing all this. In fact, there are a mind-numbing number of other ways (see that Grandfather Paradox article for examples). But seems to me that in the end it boils down to the two kinds of considerations I’ve mentioned here: Either our actions in the past were always part of history or we aren’t really living in "our" history as soon as we’ve entered the past.
Either way (and in any other scenario one might want to propose), the fundamental moral axiom still applies to us: Do good and avoid evil. The knowledge we had of how "our" history unfolded simply gives us extra information as we attempt to do that.