 As mentioned above (introduction to Section 1.2), natural kind realism may be understood as an analogue of realism about universals. A further question is whether these are simply analogues or in fact related positions. Perhaps natural kinds just are (a species of) universals or are reducible to universals. Within realism, that reductionist view can be contrasted with natural kind fundamentalism, which holds that not only are there natural kinds (as entities), but also that natural kinds find a basic and sui generis place in our ontology. We illustrate three positions within naturalism about natural kinds: (i) naturalism without (strong) realism; reductionist realism; fundamentalist realism.