 There are also other problems. Wiggins recognizes that his account of individuation of biological kinds in terms of “characteristic forms of activity” does not transfer well to prototypical artifacts. He tries to meet this concern by giving an analysis in terms of function for artifacts such as clocks. However, he seems to assume that there are not problematic intermediate cases between natural kinds and pure artifacts. Many kinds of things, e.g., rivers and lakes, can be either natural or artificial. They can also be partly artificial, as when a river is dredged or a lake enlarged. Nevertheless, Wiggins (2016, chap. 16, sec. 16–17, and chap. 12) might provide criteria for deciding upon these cases. (See Carrara &amp; Vermass (2009), Baker (2004, 2008), and Losonsky (1990), for critical discussions on Wiggins’ view on artifacts; see also the entry  on artifacts for more general discussions of this notion in diverse areas of philosophy.)