As for the science of morality, I should add that there are great scientific explanations about the evolution of morality. I was trying to explain this to my friend YA. If you look at the Classroom Clashes: Teaching Evolution discussion, you will see some of his comments there, but alas, many of his comments got deleted by the mods, and then he got banned. For some reason, he is more reluctant to accept evolution than I am, so sometimes I find myself trying to explain aspects of it to him. I was explaining how developing a sense of empathy is essential to long-term survival. I told him about how our aggressive traits have come down to us in some balance with our compassionate traits because too much of one or the other would interfere with one's survival.