The best of both worlds

1. I assume much of the appeal of time-travel scenarios and parallel universe scenarios lies in the fact that in reality, we can't go through both doors at once. There are unrealized possibilities we wish we could explore.

There are situations where, with the benefit of hindsight, we'd make a different choice. At least if we could hang onto the good things. One of the principles that time-travel stories illustrate is that when you change even one variable, that has a domino effect. By changing one variable, you change the direction of all the succeeding dominos.

2. In addition, there are situations where, if we had the benefit of hindsight, we wouldn't change anything despite having the benefit of hindsight, even if the consequences are, in some respects, undesirable. Because we know the consequences, we'd repeat the same chain of events in spite of undesirable consequences. 

For instance, suppose I have a younger blind brother. We're about a year and a half apart. Because he's more dependent on me than a sighted brother, I'm closer to him than if he was sighted. If he was sighted, it would be easier to take him for granted. 

Still, there are brotherly things I'd like us to do together that I can't do with him. I can't go hiking with him because he can't see. I mean, I could still go hiking with him, I could take him by the hand. But part of the pleasure of hiking is sightseeing, and that's not something he's in a position to appreciate. So it won't be a shared experience at that level, yet the point of doing things together is for the shared experience. This leaves me with three options:

i) Go hiking with friends, and take him along, even though he won't get much out of it. My friends and I will be talking about things we see on the trail, that he can't see. That's insensitive. 

ii) Go hiking with friends, but leave him behind. Yet that would be mean.

iii) Skip hiking to avoid the dilemma. But in that event we both miss out. 

3. Suppose I have access to the proverbial time machine. I don't know the night on which he was conceived, but I have a rough idea of the time range, and if I travel back into the past several times, I'll be able to disrupt parential activities on the crucial evening. Would I do it? Should I do it?

i) Even from a purely selfish standpoint, that might backfire. I might get a sister instead of a new brother! Not that there's anything wrong with having a sister, but if the problem is that I'm unable to do the usual brotherly stuff with my blind brother, then I can't very well do it with a sister. And it would serve me right. 

ii) Perhaps, moreover, my mother isn't very fertile. She might have a condition like polycystic ovarian syndrome. She only had a few babies on tap. By preempting my blind brother's conception, I don't get a sighted brother in his place–I get nothing. My mother only had two brothers on tap. Once again, it would serve me right.

4. From a Christian standpoint, sacrificial love is a deeper kind of love. Love that's cost-free isn't very loving. That's fair-weather love, which is barely love at all. I don't love you for you, but only for what I might get out of it. 

5. Finally, from a Christian standpoint, if my brother and I die in the faith, then in the world to come we'll be young again, and this time around my brother will be sighted. So we'll be able to do the brotherly stuff we missed out on in this life. We'll have our memories from this life, we'll have the special bond that's a carryover from his disability, but without the disability. Truly the best of both worlds. Two kinds of goods that can't happen in the same world history, but are now combined as two different world histories converge in the eschaton.