The most popular and influential strategies used against semantic externalism and the causal theory of reference are critically examined. It is argued that upon closer scrutiny, none of them emerges as truly convincing.

Philosophers have often debated the truth of microstructural essentialism about chemical substances: whether or not the structure of a chemical substance at the molecular scale is what makes it the substance it is. Oddly they have tended to pursue this debate without identifying what a structure is, and with some confusion and about what a chemical substance is. In this paper I draw on chemistry to rectify those omissions, providing a pluralist account of structure, clarifying what (according to chemistry) a (...) chemical substance is and defending microstructural essentialism, as I understand that position. I then give an account of the existence of composite substances and objects in chemistry, an issue that goes back to Aristotle. (shrink)