Chemistry, philosophical aspects of

Chemistry, like all theoretical sciences, is deeply rooted in philosophical inquiry. Early Greek atomism was a response to Parmenides’ argument that the very concept of change is unintelligible. Aristotle in turn argued that a vacuum is impossible and proposed that qualitative change could be better understood in terms of four elements and an underlying prime matter.

During the Arabic and Latin Middle Ages, philosophical commentaries on the nature of materials were brought into juxtaposition with the practical arts of the alchemist, miner and pharmacist. As chemical speculations became more closely connected to observations during the time of the Scientific Revolution, natural philosophers became more and more interested in the methodological aspects of chemistry. Galileo and Locke tried to clarify the relationship between primary and secondary qualities. Boyle struggled to understand how the selective affinities so characteristic of chemical reagents could be explained within the framework of Descartes’ mechanical philosophy. Lavoisier’s textbook was organized around principles drawn from philosophes such as Condillac.

As chemistry became an autonomous science, chemists turned less often to philosophy as a source of theoretical inspiration. However, they frequently appealed to philosophies of science in order to defend their own theories or criticize those of their opponents. The so-called ’atomic debates’ amongst chemists in the British Association during the 1860s were primarily disputes about the epistemological legitimacy of appeals to unobservable entities. Many of the same issues were taken up at the end of the century by Ostwald, Mach and Duhem.

Logical empiricists in the twentieth century have often turned to chemistry as an example of the successful reduction of a secondary science to physics. Thus, it is claimed that the laws of classical thermodynamics, expressed using concepts such as enthalpy and entropy, can be derived from the laws of statistical mechanics describing the motions of particles. The details of this purported derivation have been questioned. Even more controversial is the attempt to derive accounts of the chemical bond and the shape of molecules from the first principles provided by quantum mechanics.