Comments on Gideon Rosen’s “What is Normative Necessity?”

Gideon Rosen supports the central theses of “Varieties of Necessity” (VN) concerning the distinction between metaphysical and normative necessity and the proper formulation of moral supervenience; and he takes the defense of these theses much further than I did in my own paper and makes the case for them especially vivid and compelling. I was especially impressed by his attempt to find out what might lie ...

Why Believe in Normative Supervenience?

According to many, that the normative supervenes on the non-normative is a truism of normative discourse. This chapter argues that those committed to more specific moral, aesthetic, and epistemic supervenience theses should also hold (NS*): As a matter of conceptual necessity, whenever something has a normative property, it has a base property or collection of base properties that metaphysically necessitates the normative one. The main aim in this chapter is to show that none of the available arguments establish (NS*), or indeed the relevant epistemic, aesthetic, and moral supervenience theses. (NS*) is not a conceptual truth. This has considerable dialectical importance. One interesting upshot is that it affords non-reductivists and non-naturalists a novel way of resisting certain prominent supervenience-based objections to their views, including objections that formulate supervenience as a purely metaphysical thesis.

Moral supervenience

It is widely held, even among nonnaturalists, that the moral supervenes on the natural. This is to say that for any two metaphysically possible worlds w and w′, and for any entities x in w and y in w′, any isomorphism between x and y that preserves the natural properties preserves the moral properties. In this paper, I put forward a conceivability argument against moral supervenience, assuming non-naturalism. First, I argue that though utilitarianism may be true, and the trolley driver is permitted to kill the one to save the five, there is a conceivable scenario that is just like our world in all natural respects, yet at which deontology is true, and the trolly driver is not permitted to kill the one to save the five. I then argue that in the special case of morality, it is possible to infer from the conceivability of such a scenario to its possibility. It follows that supervenience is false.