On the ontological status of molecular structure: is it possible to reconcile molecular chemistry with quantum mechanics?

SEBASTIAN FORTIN; MARTÍN LABARCA; OLIMPIA LOMBARDI

FOUNDATIONS OF SCIENCE

SPRINGER

Lugar: Berlin; Año: 2023 vol. 28 p. 709 - 725

1233-1821

Accordingto classical molecular chemistry, molecules have a structure, that is, they aresets of atoms with a definite arrangements in space and held together bychemical bonds. The concept of molecular structure is central to modernchemical thought given its impressive predictive power. It is also a veryuseful concept in chemistry education, due to its role in the rationalization andvisualization of microscopic phenomena. However, such a concept seems to findno place in the ontology described by quantum mechanics, since it appeals toclassical notions such as the position of the atomic nuclei or theindividuality of electrons. Although this problem has attracted the attentionof several authors, the discussion is far from settled. Some authors adopt anexplicitly reductionist position and advocate to reconstruct the concept ofmolecular structure within the framework of the quantum theory. Others,although acknowledging the conceptual discontinuity between quantum mechanicsand molecular chemistry, keep the hope of future reduction alive. From anexplicitly non-reductionist position, on the contrary, others authors conceivemolecular structure as an emergent phenomenon.Thepurpose of this article is to propose a different line of argumentation toaddress this problem. By contrast to reduction and emergence, the admission ofa multiplicity of ontologies, not necessarily linked by hierarchical connections,cancels the need of finding a relation of dependence between the molecularlevel and the quantum level. This ontologically pluralist position can beapplied to the issue of molecular structure, in order to argue that it ispossible to admit the existence of structure in the ontology of molecularchemistry, in spite of the fact that it does not exist in the quantum world.