 The heart of Rosen’s challenge is an argument that we can characterize and clearly regiment a notion of normative necessity, which falls short of metaphysical necessity (i.e. at least some normative necessities are metaphysically contingent), while still being quite strong, in the sense that in any counterfactual where one considers how things would be if we altered some non-normative fact, we hold fixed the normative necessities. Rosen proposes that normative necessity is the appropriate modality for ethical supervenience. If he is correct about this, most of the arguments from supervenience discussed so far would fail, as they tend to require ethical supervenience to have either metaphysical or conceptual strength.