What can science tell us about morality? Many philosophers would say, 'nothing at all'. Facts don't imply values, they say. you need further argument to move from facts about us and about the world to conclusions about what we ought to do. For example, most humans are altruistic - they genuinely care about the well-being of friends and family and to a lesser extent even of strangers - they'll give money to charity to help people they've never even met. Suppose science gives us a compelling scientific explanation for why we're altruistic. Does that tell us whether we should be altruistic?