 Giving examples of perfectly natural properties is not supposed to be easy. Views that identify certain properties as perfectly natural are bold hypotheses about the fundamental structure of reality, and thus bound up with many central debates in metaphysics. According to Lewis, the methods of physics have a central role to play in the project of identifying the perfectly natural properties. Until we have the kind of final theory that many physicists are aiming for, we should not hope to be able to list the actually-instantiated perfectly natural  properties.[2]  But looking to physics in this way is already taking a stand on many controversial questions in philosophy. Those inclined towards dualism in the philosophy of mind (see the entries on  dualism  and  physicalism)  may hold that some mental properties—for example, consciousness, or specific phenomenal states, or relations like acquaintance, judgment or knowledge—are perfectly natural; indeed, this might with some plausibility be regarded as definitive of dualism. Similarly, those inclined towards “non-naturalist realism” in metaethics (see the entry on  moral non-naturalism)  may hold that some normative or evaluative properties, such as goodness, betterness, or moral permissibility, are perfectly natural.