Abstract

In Chapters 4 and 5 of his 1998 book From Metaphysics to Ethics: A Defence of Conceptual Analysis, Frank Jackson propounds and defends a form of moral realism that he calls both ‘moral functionalism’ and ‘analytical descriptivism’. Here we argue that this metaethical position, which we will henceforth call ‘analytical moral functionalism’, is untenable. We do so by applying a generic thought-experimental deconstructive recipe that we have used before against other views that posit moral properties and identify them with certain natural properties, a recipe that we believe is applicable to virtually any metaphysically naturalist version of moral realism. The recipe deploys a scenario we call Moral Twin Earth.