The debate between ontological reductionists and emergentists in chemistry has revolved around quantum mechanics. What Franklin and Seifert (BJPS 2020) add to the long-running dispute is an attention to the measurement problem. They contend that all three realist interpretations of the quantum formalism capable of resolving the measurement problem also obviate any need for chemical emergence. I push their argument further, arguing that the realist interpretations of quantum mechanics actually subvert the basis for reduction as well, by undercutting the idea (...) that fundamental physical particles are actual parts of molecules. With both reduction and traditional synchronic emergence pictures ruled out, the only option for realists about quantum chemistry is strong Thomistic emergence. (shrink)

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)

Around fifteen years before the chemical substance alumina could be decomposed in the laboratory, it was identified as a compound and predicted to contain a new element called ‘aluminium’. Using this episode from early nineteenth-century chemistry as a case study for the use of analogical reasoning in science, this paper examines how chemists relied on chemical classifications for the prediction of aluminium. I argue that chemists supplemented direct evidence of chemical decomposition with analogical inferences in order to evaluate the composition (...) of substances. Since they were established on the basis of relevant similarities in chemical properties, classifications were taken to reflect so-called ‘chemical analogies’ between substances. In combination with the knowledge that analogous properties indicated similarities in composition, this enabled chemists to infer the composition of experimentally indecomposable substances by analogy. The trust in such analogical inferences, even if they could not be confirmed through experiment, was justified by pragmatic considerations. Whereas the possibility of decomposing a substance depended on the available laboratory techniques, chemical analogies were thought to last independently of internal composition. It was therefore more practical to keep well-established classes of substances together rather than separate them on the basis of experimental results that might evolve as new techniques were developed. Besides highlighting the links between analogical reasoning and classification, this paper also illustrates the importance of analogy in the evaluation of elementary nature in the early nineteenth century. (shrink)