 Realism about natural kinds is the view that there exist entities that are the natural kinds. While naturalism about natural kind classifications is a matter of there being natural groupings and distinctions among things and as such has no ontological commitment, realism is an ontologically committed view. Since ‘(weak) realism’ is sometimes used to denote naturalism, we may distinguish by using the term strong realism for the stronger, ontological, claim that the natural divisions between kinds reflect the boundaries between real entities; i.e. the difference between silver and gold is not just a difference between two natural groups of thing, but is a difference between two distinct entities silver and gold.