Superman is in an odd position, he has the power to know when anyone is in danger and the power to do something about it (at least the older superman did). Does being superman bring any special ethical responsibilities with it?
I think the natural response is to say that yes, superman does have additional responsibilities. Specifically he has the responsibility to save from harm everyone that he can, which in his case literally means everyone. We arrive at this conclusion simply from extrapolating from our normal ethical responsibility to help those that we can. But superman’s duty to help people would be more demanding than ours is. We don’t have to help every person we meet, because sometimes helping them would result in harm to us, so that the net result is more harm than good. We are also allowed to take “time out” from watching out for other people, by which I mean that we don’t always have to be out looking for people to help, if we want we can stay home. This is because there is a benefit to us in staying home (or doing anything else besides actively looking for people to help), and since we are unlikely to actually help someone even if we are looking to, we can justify that choice. But superman doesn’t have this leeway. Superman is only inconvenienced in the slightest when he helps people, and certainly there is never any danger to him (we are considering the real world here, one without supervillains). And even if superman could use a day off once in a while he can’t justify taking it, as a normal person might, since the amount of good that he could do far outweighs any benefits to him from time off.
But the ultimate foundation behind the moral “rules of thumb” I have extended to cover the case of superman is that society as a whole is better when we all live by such rules. But is a society containing a superman who lives by these rules better? Certainly in many ways it would be. Crime and wars would become almost non-existent. But there might be downsides too. People would live dangerously simply because they know that they can. You wouldn’t need to fly by plane, you could simply strap yourself to a rocket and wait for superman to catch you. This downside I think we could live with, but there are more serious problems. For example, superman would use his powers to feed and house the poor, which seems like a good idea, but it might also drive farmers and builders out of jobs. Why pay for a house when you can get one from superman for free? Now eliminating these jobs isn’t necessarily a bad thing, and if we could build food and housing producing machines I think we should. The problem is that people would become, in general, dependant on superman. Now we could argue that we are dependant on our machines too (for example our fictional house building machines), but the difference with machines is that we made them, and thus we can strive to improve them or make better machines. But superman is out of our control, and I think a world that was taken care of by a real superman would quickly stagnate.
However, the solution is not for superman to do nothing either. He simply must limit his good works so that they avoid stagnating society. This would mean that he should still fight crime and save people from disasters. However he should keep his feeding and housing of the poor limited (although not non-existent). Likewise it might be best for him to help only people in trouble who have taken every other precaution. This would encourage people to look after themselves and still let superman save most people (since, knowing that taking every precaution is a perfect guarantee of safety, most people would probably be even more cautious). Perhaps the way superman is portrayed in the comics really is the best possibility, he helps those in need but mostly stays out of the affairs of common people.
Now of course I could make the analogy between superman and god, and argue that if god is good he should behave in basically the same way as superman. But I won’t, because the analogy is so obvious. Instead I will mention that superman, having been raised like a normal person, might be unable to stop himself from interfering too much. After all, if you could really hear everyone’s problems, how could you not?