 For these reasons, microessentialist claims would need to be grounded in chemical classification and explanation: the systems of nomenclature developed by IUPAC are based entirely on microstructure, as are theoretical explanations of the chemical and spectroscopic behaviour of substances (see Hendry 2016). On the other hand, H2O content fails to track usage of the term “water” by ordinary-language speakers, who seem to have different interests to chemists (Malt 1994). Pluralism is one response to these tensions: Hasok Chang (2012) urges that even within science, water’s identity with H2O should be left open; Julia Bursten (2014) tries to reconcile the special role of microstructure in chemistry with the failure of microessentialism; and Joyce Havstad (2018) argues that chemists’ use of substance concepts is just as messy and disunified as biologists’ use of various species concepts.