 The thesis used to introduce supervenience above—Initial—suggested that the ethical supervenes on the natural properties. This is the most common way of characterizing ethical supervenience in the literature. However, there are at least two difficulties with this idea. The first difficulty is ambiguity: the term ‘natural’ has been characterized in wildly varying terms in metaethics (see the introductory section of the entry on  moral non-naturalism  for a brief survey of characterizations of the natural; see McPherson 2015, §3–4 for one constructive proposal). The second difficulty is that on many conceptions of the natural there will be counterexamples to Initial. For example, many philosophers want to contrast natural properties with supernatural properties. Even if we assume that there are no actually instantiated supernatural properties, we might allow that such entities are possible. But this might in turn seem to suggest that two possible states of affairs could be naturalistically identical, but ethically different. For example, they might be different because of ethically significant interactions between supernatural beings (Klagge 1984, 374–5; for some complications see McPherson 2015, 134–5).