 Naturalism need not maintain that all the classifications we in fact take to be natural are indeed natural. Sometimes scientists and others err in the natural kinds they take to exist. There is no kind that is phlogiston or phlogisticated air. Many might suppose jade to be a natural kind of mineral, but it is not because there are two distinct minerals called ‘jade’. (See LaPorte 2004, 94–100 and Hacking 2007b for detailed discussions of jade.) Similarly, biologists now believe that reptiles do not form a natural kind. Naturalism is the view that there are in fact natural divisions among things, so that when we attempt to make a natural classification, there is a fact of the matter as to whether that classification is indeed genuinely natural.