  Perhaps the most vexing problem for any general characterization of non-naturalism is the bewildering array of ways in which the distinction between natural and non-natural properties has been drawn. Natural properties have variously been characterized as properties that (i) are the subject matter of the natural sciences (Moore 1903: 40), (ii) are invoked in scientific explanations (Little 1994: 226), (iii) would be identified by the best scientific theory and can be described in conceptual terms available to a being occupying a non-local point of view on the world (Crisp 1996: 117), (iv) can be known only a posteriori (Copp 2002, Moore 1903: 39), (v) can exist by themselves in time (Moore 1903: 41), (vi) confer causal powers (Lewis 1983), (vii) figure in the laws of nature (Vallentyne 1998), or (viii) explains similarity relations (Lewis 1983), e.g. why a black cat is more similar to a white cat than to a black dog. The first four of these characterizations are epistemological, and three of those four are cast explicitly in terms of scientific inquiry; the remaining three are metaphysical.