What is normative necessity?

This chapter explores Fine’s suggestion that the ethical facts supervene on the natural facts, not as a matter of metaphysical necessity, but rather as a matter of normative necessity. The first part develops an argument against the metaphysical supervenience of the ethical, the main premises of which are ethical non-naturalism and Fine’s essentialist analysis of metaphysical necessity. The second part defends an analysis of normative necessity according to which P is normatively necessary iff P would have been the case no matter how the non-normative facts had been. The last part argues that the basic principles of ethics as the non-naturalist conceives them are indeed normatively necessary in this sense.