 Jonathan Dancy (1995, 278–9) and Debbie Roberts (2018) have suggested that attention to thick ethical concepts casts doubt on ethical supervenience. The core idea is this: it is true that there are no thin ethical differences between otherwise identical circumstances. However, it is suggested that sometimes the thin ethical properties of an action or event are best explained by citing thick ethical properties. And it is claimed that it is not at all clear that these thick ethical properties can always be explained in purely base terms (see especially Roberts 2017a).