My brother pointed out an interesting video by Jeremy Rifkin here, on what Rifkin calls The Empathic Civilization. The basic idea is that we are hardwired for empathy and should strive to expand our range of empathy beyond tribe and nation to embrace the whole world, and even into the animal kingdom.
That's all well and good, but the problem is that empathy by itself isn't enough to serve as a moral guide. I may feel empathy for both the Red Sox and the Cardinals in the World Series, but one of them has to win and one of them has to lose. More seriously, our moral life often consists in making difficult choices between parties both of whom may engage our empathy. We may empathize with the poor man and support taxes to help him, but might we not also empathize with the working man who has his life's work confiscated from him through those taxes? We may empathize with the young woman who finds herself pregnant when she didn't plan it, but what about empathy for the unborn child in her womb who finds himself a potential victim of abortion? Empathy by itself doesn't decide which empathy takes precedence.
Even when empathy has a clear focus, it is not always a good guide. We may empathize with a child getting a shot, but we understand that the shot is in the best interests of the child even if getting it is unpleasant. More important than empathy is a well-developed sense of justice, which is simply willing the good for others - whether we empathize with them or not. We owe it to a child to give him the shots he needs whether he likes it or not, and however we feel about it.
Using empathy as a moral guide is to mistake the engine for the captain. Empathy can drive us to act for the good of others, but it doesn't by itself reveal what that good is or how it is to be achieved, nor how to balance competing goods. For that we need justice.