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  • Writer's pictureMarina Paola Banchetti-Robino

Beyond Cartesian Mechanicism: Robert Boyle’s Chemical Philosophy

The modern study of chemistry has its foundations in the alchemy of the Middle Ages, the Renaissance, and the early 17th century. In this period, great progress was made towards a better and more accurate understanding of chemical substances, including their structure, properties, and how they relate to one another. One of the most prominent thinkers to make advances in these areas was the Irish chemist Robert Boyle. In my book The Chemical Philosophy of Robert Boyle: Mechanicism, Chymical Atoms, and Emergence, I offer an analysis of the contributions made by Boyle and of his chemical philosophy as it related to the dominant Cartesian mechanistic theory of matter. Building on Descartes’ mechanistic view, Boyle succeeded in rooting the mechanical philosophy in empirical experimentation, while also accounting for the emergent and non-reducible nature of chemical properties. In doing so, he was also affirming the autonomy of chemistry from more fundamental sciences such as mechanics and its legitimacy as a theoretical and experiment science, with its own distinctive objects of study and its own distinctive explanatory framework. These concerns are still pertinenet for contemporary chemistry and philosophy of chemistry. This book advances Boyle scholarship by going beyond other researchers and providing a detailed look at the parts-whole relations within chemical atoms as conceptualized by Boyle. That is, the book examines in detail the relation between fundamental particles and their mechanistic properties and the properties of complex wholes made of such particles.

Before explaining Boyle’s critiques of his predecessors, the book situates Boyle’s thought its appropriate historical and philosophical context, that is, into the context of the alchemy and chemical philosophies of the 16th and 17th centuries. Before modern chemistry had established itself as a hard science, comparable to physics and astronomy, the greatest philosophical and scientific minds of Europe focused their energies on the development and practice of alchemy, which involved the transformation of substances by understanding their physical constitution. The practice of alchemy, however, was grounded in a vitalistic conception of matter that viewed all substances in nature as imbued with a kind of ‘life’ force that governed their behavior. The chemical philosophy of the Middle Ages and Renaissance was also dominated by the Scholastic theory of substantial form, which held that matter is organized and made intelligible and stable by the presence of non-physical forms. This was a view that came under sustained attack from the 17th century mechanical philosophy and one for which Boyle sought to find a better alternative. The book explores several other ideas, including the alchemical theory of the tria prima, which posits that all substances are composed of salt, sulphur, and mercury, as well as the experiments carried out by the alchemists Daniel Sennert and Jan Baptista van Helmont, which inspired some of Boyle’s most important chemical experiments.

Cartesian Rationalistic Mechanicism

In contrast to the alchemical theories that dominated the 16th and 17th centuries, early modern chemical theories tended to embrace the mechanistic view of matter that conceptualized the nature of matter as consisting of fundamental particles, which had only the mechanistic properties of shape, size, and motion or rest. The mechanistics philosophy rejected the presence of any type of forces in nature and explained the behavior of all material substances solely in terms of the mechanistic properties of fundamental particles. There were several iterations of the mechanistic philosophy, one of which was the Cartesian corpuscularian view and another of which was the modern atomistic theory. Cartesianism differed from atomism in that, although atomists believed fundamental particles to be absolutely simple and indivisible, Descartes argued that all material particles no matter how small were always divisible at least in theory. Boyle tended to agree with the corpuscular view but also with Pierre Gassendi’s ‘molecular’ theory that corpuscles could form structured combinations with varying degrees of complexity.

Although Boyle endorsed the mechanical philosophy, he identified a tension between the Cartesian mechanistic worldview and observations from real-world chemical, pneumatic, and hydrostatic experiments. For example, Descartes’ strict mechanistic philosophy could not account for the causal nature of chemical properties or why these properties changed when substances were chemically analyzed or synthesized. Descartes’ view was, therefore, inconsistent with the results yielded by scientific experimentation. This book explains how Boyle sought to resolve these conflicts, while continuing to embrace both the mechanistic view of fundamental matter and the reality and causal efficiency of chemical properties. However, before discussing Boyle’s deeply complex chemical philosophy, the book first outlines how he abandoned the dominant Scholastic theory of substantial form and, instead, advanced the idea that chemical substances originate in and find stability from the internal structure of their complex corpuscular concretions, which give a substance its various chemical and sensible properties. According to Boyle, different corpuscular structures account for different substances and different properties, and he develops a theory that incorporates the hierarchies that exist within chemical structures and compositions. Thus, he is one of the first practicing chemists to advocate for the idea of microstructure, although he did not use this modern terminology, but he also uses experimental findings to lend empirical support to the theory of microstructural composition.

Boyle’s View of Chemical Properties and the Relation Between Parts and Wholes

In addition to discussing Boyle’s conception of complex microstructural composition, which in some ways anticipated the discovery of molecular structure in the 19th century, the book also analyzes Boyle’s ideas on the fundamental nature of chemical properties, arguing that he considered such properties as being dispositional, relational, and emergent. Since the emergent properties of a substance cannot be simplistically reduced to the mechanistic properties of its constituent corpuscles, it follows that such properties cannot be fully explained or understood through a reductivist mechanistic conception of fundamental matter. Boyle’s view supports the idea that chemical theories are not reducible to purely physical theories and that chemistry as a science must retain its scientific autonomy from physics. This was a very important conclusion for Boyle and one that set him apart from Descartes and his followers, according to whom chemistry could never be considered a genuine and autonomous science.

Mereology, as the formal study of the relationship between parts and wholes, dates back to the philosophy of Aristotle. Because chemistry as a science essentially involves the study of the relationship between parts and wholes, it easily lends itself to the application of mereological analyses. By applying a mereological analysis to Boyle’s conception of structured chemical wholes, this book makes a truly original contribution to Boyle studies. It concludes that such an analysis supports the argument that Boyle viewed chemical properties as dispositional, relational, and emergent. The author argues that Boyle regards corpuscles as the parts and their aggregate structured composition as the whole. It is not the parts but the whole that accounts for the properties of chemical substances. These ideas are explored by referencing mereological theories that were developed in the Middle Ages but that were still relevant during the time of Boyle and with which early modern philosophers and scientists would have been familiar.

By both situating Boyle’s ideas in their appropriate historical and philosophical context and providing a deep conceptual analysis of those ideas, the author has cemented the importance of Robert Boyle in the history of chemical philosophy. The book shows how Boyle moved past the Scholastic theory of substantial forms and the theories that dominated Renaissance alchemy and how he was able to build upon the Cartesian mechanistic theory of philosophy while avoiding some of its most problematic implications for chemistry. By supporting his chemical philosophy with empirical observations of his own experimental work, Boyle took chemical philosophy to the next level and anticipated many of the issues that are currently being debated in the philosophy of chemistry. This underlines not only Boyle’s most important contributions to early modern chemical philosophy but also underlines the enduring relevance of his ideas.

* Marina's book is published by Oxford University Press and can be found here

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