Will Wilkinson and Jesse Prinz. Highly recommended. You could easily spend four years at an Ivy League college and not have a class as interesting as this one.
Prinz works through the view that moral values are highly culturally determined. One fascinating tidbit concerns early Christianity. Christian sexual morality made it more difficult for people to ensure that they had heirs. At first, you would think that this would have adverse survival consequences for the survival of the society. But think about the survival consequences for the Church, which gets to inherit the money from the people who die heirless.
In my view, the dialog builds to a crescendo at the end, so listen to the whole thing.