Milk, Honey, and The Good Life on Moral Twin Earth

In “Milk, Honey, and the Good Life on Moral Twin Earth”, David Copp explores some ways in which a defender of synthetic moral naturalism might attempt to get around our Moral Twin Earth argument.1 Copp nicely brings out the force of our argument, not only through his exposition of it, but through his attempt to defeat it, since his efforts, we think, only help to make manifest the deep difficulties the Moral Twin Earth argument poses for the synthetic moral naturalist. Our response to Copp will be in two stages. First we will make some general observations about our argument that help one appreciate its force, and then we will turn to the details of Copp’s proposals.