 It is noteworthy that it is often rather difficult to draw the line between these two versions of non-reductive physicalism. This is mainly due to the fact that the notion of a type or a natural kind is far from clear. Hempel, for example, tentatively suggests that what makes a type/kind a mental type/kind is that it is referred to within psychology or psychological theories (Hempel 1969); thus the nature of a kind or type becomes dependent upon the context in which we refer to it, which in turn might be epistemically or pragmatically constrained. Fodor suggests that being a kind is to be mentioned in a law; and that the locution ‘it is a law that…’ generates intensional contexts, i.e., contexts that are sensitive to how things are referred (Fodor 1974: 109). Hence, being a kind again might not be an all-or-nothing affair. If to be a kind is to play a certain epistemological role (this is, to be sure, not Fodor’s official point), then the distinction between ontological and epistemic versions of non-reductive physicalism (and, analogously, between ontological and epistemological reductionism) might be hard to spell out.