The Supervenience Challenge: An Explanation

It is almost universally held in metaethics that there cannot be a normative difference without a natural difference—any two situations that are exactly alike in every natural respect will be exactly alike in every normative respect. When supervenience holds, especially with metaphysical necessity, this calls for explanation. On the one hand, if no explanation can be offered, non-naturalism is left committed to a metaphysically necessary coincidence. Some see this as a significant cost for the view, and others as an outright refutation. On the other hand, the usual metaphysical tools used to explain supervenience—identity, reduction, constitution, etc.—would all bear the implication that the normative is natural. Explanations must meet three constraints. First, provide schematic structures that explain necessary coextension. Second, offer schematic resources for guaranteeing the right necessary coextension. Third, explanations for specific supervenience relations must not make it more difficult or impossible to explain general supervenience. Non-naturalists can meet these constraints while reducing their commitment to bruteness. Given the dialectic, reduction is sufficient. There are few metaphysical resources for explaining supervenience compatible with non-naturalism. Proposals that use only natural properties to explain supervenience will clearly be naturalist. Proposals that use only normative properties will fail to be sufficiently explanatory. Proposals that use both normative and natural properties, and nothing further, will either be naturalist or fail to be explanatory. This leaves non-naturalists a final option of including some third kind of element, for example normative principles “Third-element” explanations must make clear i. what normative properties are like such that third-elements partially explain their distributions, and ii. what third-elements are like, such that they explain the distributions of normative properties. On my account, normative properties are relational properties holding between normative principles and the primary focus of normative evaluation. Normative principles must be content-bearing entities that bear their contents essentially, analogous to necessarily existing and sui generis rules or laws. This rejects the view that principles are fundamental normative facts. Principles are still fundamental normative entities, and there are facts about which principles bear which content, but normative principles are not themselves facts. This view meets all the constraints above