 A common view concerning our so-called natural kind classifications is that there are genuinely natural ways of classifying things. Intuitively, to group all instances of the metal zinc together is to engage in a natural classification, whereas to group together Trajan’s column, the number two, and Julius Caesar is to classify things in an arbitrary manner. The classifications ‘cars manufactured in Germany’, ‘culinary vegetables’, ‘altars’ are not arbitrary, but neither are they natural, since they reflect human interests. This view we call naturalism. It is often called realism because of the close affinity to scientific realism; indeed naturalism may be regarded as a consequence or component of standard scientific realism. Scientific realists hold that successful scientific theories represent theory-independent phenomena. Thus the theoretical posits of science reflect natural divisions in nature; for example, the periodic system for classifying the chemical elements reflects natural divisions between the elements. However, since ‘realism’ is also associated with ontological doctrines (e.g., realism about universals, modal realism etc.) it would be preferable to use weak realism (or, as above, naturalism) to label the ontologically uncommitted view that our classifications are often natural. (We will note below that not all natural classifications are classifications into natural kinds.)