Name given by Moore to properties, notably ethical properties, that are not natural, i.e. not the kind of property mentioned in a scientific and empirical description of the world. The existence of such properties is contested by both emotivists and other non-cognitivists, who do not think in terms of there being real moral properties at all. Their existence is also queried by latter-day naturalists, who seek to identify ethical properties with varieties of natural property. The problem with Moore's separation of natural and non-natural properties is that it seems to leave him with no reasonable way of knowing about the latter type, and although he defended an ethical intuitionism, the term ‘intuition’ seems to many philosophers merely to label the difficulty. See also fact/value distinction.