  This “new epiphenomenalism” (Campbell 1984, ch. 7) immediately confronts a particularly strong version of property dualism,  one insisting that mental properties are sui generis, perhaps dependent on, but in no way reducible to the dispositional and structural properties recognized by the physical sciences. Some property dualists accord this status only to a certain class of mental property, namely  qualia, the “what it’s like” features of conscious experience. Other property dualists, including some emergentists, are willing to extend the thesis to all mental properties.