This is a beautiful thought experiment, and a really interesting argument. I wonder if saying that it shows an incompatibility between moral realism and time discounting is too strong though? Maybe it only shows an incompatibility between time discounting and consequentialism?
Under non-consequentialist moral theories, it is possible for different moral agents to be given conflicting aims. For example, some people believe that we have a special obligation towards our own families. Suppose that in your example, Anna and Christoph are moving towards their respective siblings, and we neglect relativistic effects. In that case, both Anna and Christoph might agree that it is right for Anna to take the carrot, and that it is also right for Christoph to take the carrot, even though these aims conflict. This is not inconsistent with moral realism.
Similarly, in the relativistic case, we could imagine believing in the moral rule that “everyone should be concerned with utility in their own inertial frame”, together with some time discounting principle. Both Anna and Christoph would believe in the true statements “Anna should take the carrot” and “Christoph should take the carrot”. They would acknowledge that their aims conflict, but that is not inconsistent with moral realism.
I think the analogy here is quite strong, because you could imagine a time discounter defending their point of view by saying we have stronger obligations to those closer to us in time, in the same way that we might have stronger obligations towards those closer to us in space, or genetically.
On the other hand, when you consider General Relativity, there are no global inertial frames, so it’s interesting to imagine how a steelmanned time discounter would adapt the “everyone should be concerned with utility in their own inertial frame” principle to be consistent with General Relativity. Maybe anything they try would have some weird consequences.
This is a beautiful thought experiment, and a really interesting argument. I wonder if saying that it shows an incompatibility between moral realism and time discounting is too strong though? Maybe it only shows an incompatibility between time discounting and consequentialism?
Under non-consequentialist moral theories, it is possible for different moral agents to be given conflicting aims. For example, some people believe that we have a special obligation towards our own families. Suppose that in your example, Anna and Christoph are moving towards their respective siblings, and we neglect relativistic effects. In that case, both Anna and Christoph might agree that it is right for Anna to take the carrot, and that it is also right for Christoph to take the carrot, even though these aims conflict. This is not inconsistent with moral realism.
Similarly, in the relativistic case, we could imagine believing in the moral rule that “everyone should be concerned with utility in their own inertial frame”, together with some time discounting principle. Both Anna and Christoph would believe in the true statements “Anna should take the carrot” and “Christoph should take the carrot”. They would acknowledge that their aims conflict, but that is not inconsistent with moral realism.
I think the analogy here is quite strong, because you could imagine a time discounter defending their point of view by saying we have stronger obligations to those closer to us in time, in the same way that we might have stronger obligations towards those closer to us in space, or genetically.
On the other hand, when you consider General Relativity, there are no global inertial frames, so it’s interesting to imagine how a steelmanned time discounter would adapt the “everyone should be concerned with utility in their own inertial frame” principle to be consistent with General Relativity. Maybe anything they try would have some weird consequences.