Supervenience arguments against robust moral realism

Abstract

The relation of supervenience of the moral on the natural is the main premise of two objections recently leveled at non-reductivism in metaethics. These objections start with moral supervenience and conclude with the untenability of robust, non-reductive moral realism. The paper states the most plausible supervenience thesis in metaethics and elucidates some relevant assumptions and consequences of the supervenience view (§ 2). It then deals with the first supervenience argument, the Co-Extensiveness Argument. The main issue here concerns the ontological legitimacy of infinitely disjunctive properties and the need to meet the particularist challenge, which leads to the rejection of the Co-Extensiveness Argument (§§ 3-5). The target of the next sections is the second supervenience argument, the Explanatory Argument. Their aim is to make clear that the standard type of reduction by identity leads to the result that reductive realism has the same purportedly unsolvable explanatory problem proponents of the Explanatory Argument critically attribute to robust realism (§§ 6-8). Finally, it is argued that a novel type of reduction recently proposed by Mark Schroeder, reduction by analysis, can solve this problem on behalf of reductionism. But contrary to first appearances, this is good news, not bad news, for robust realism (§§ 9-10).

Keywords: moral supervenience, reductivism in metaethics, robust realism, reduction by identity, reduction by analysis, explanation of necessary connections.