Philosophers have also discussed classification at the interface of biology and chemistry. Goodwin (2011) has argued that structure is fundamental and sufficient for classification of biomolecules, such as proteins. Tobin (2010a) and Slater (2009) appeal to developments in the relationship between protein structure and function in a number of cases such as moonlighting proteins, intrinsically unstructured proteins, and enzymes with multiple structural variants. They claim that the path from stru