Abstract

Different chemical species are often cited as paradigm examples of structurally delimited natural kinds. While classificatory monism may thus seem plausible for simple molecules, it looks less attractive for complex biological macromolecules. I focus on the case of proteins that are most plausibly individuated by their functions. Is there a single, objective count of proteins? I argue that the vagaries of function individuation infect protein classification. We should be pluralists about macromolecular classification.