Introduction
It would seem that philosophy of chemistry emerged only recently. In the early 1990s philosophers and chemists began to meet in many different countries to discuss philosophical issues of chemistry - at first in isolated national groups but soon cultivating international exchange through regular meetings and the publication of two journals (Hyle and Foundations of Chemistry) devoted to the philosophy of chemistry.
While the social formation is indeed a recent phenomenon, which is still in progress, the philosophical topics have a much longer history, which in some cases predates chemistry. One could even argue that ancient Greek natural philosophy started with profoundly chemical questions about the elemental constitution of the world and about how to provide explanations for the sheer unlimited material variety and its wondrous changes, in which, for instance, water becomes solid or gaseous; wood turns into fire, smoke, and ashes; stones change into metals; food transforms into the human body; or certain materials convert a sick body into a healthy body.In fact, there is an almost continuous philosophical tradition focused on such questions. Because Aristotle’s natural philosophy, which was centered on his theory of elements, was influential far into the eighteenth century, it provided the basis for much of chemical philosophy. The meticulous arts of performing desirable material changes in the laboratory, particularly alchemy and metallurgy, were deeply involved in pondering metaphysical and methodological issues, out of which not only modern chemistry but also the experimental method emerged, which influential figures like Francis Bacon popularized.
Although the seventeenth century brought about a fundamental split into the mathematical and experimental sciences and many famous philosophers were inclined towards the mathematical tradition, philosophical discussions of chemical issues did not stop then.
For instance, Immanuel Kant, at least in his posthumous works, wrote extensively on chemistry, as did G.W.F. Hegel, F.W.J. Schelling, and particularly Friedrich Engels, whose dialectical materialism later inspired twentieth-century generations of philosophers in communist countries to reflect on chemistry. Outstanding nineteenth- and twentieth-century chemists, from Justus Liebig to Pierre Duhem, Wilhelm Ostwald, and Michael Polanyi, were heavily engaged in philosophical issues, although their influence gradually faded as philosophy of science established itself as an independent branch of philosophy in the twentieth century. Particularly in German- and English-speaking countries, professional philosophers of science became almost exclusively focused on the mathematical tradition, with favorite topics in statistics, mathematical logic, relativity theory, and quantum mechanics. While their work has without doubt been important to theoretical physics, they mistakenly consider this peculiar research field to be exemplary or representative of all the sciences. Apart from communist countries, the situation was different perhaps only in France, where two chemically trained philosophers, Emile Meyerson and Gaston Bachelard, were most influential in shaping French epistemologie and philosophy of science. In most countries, however, the gap left by philosophers of science was largely filled by chemists and historians of science, like Thomas Kuhn who developed his theory of paradigm changes on the model of the chemical revolution. The narrow focus of professional philosophers of science was only slowly opened, particularly through the philosophy of biology movement since the 1970s. Other philosophies of the special sciences followed soon, one of which is philosophy of chemistry.In this essay I will not try to review all the recent and past works in the philosophy of chemistry (for review articles, see Schummer 2003a, 2006), because the topics are far too diverse and many require detailed chemical background knowledge. Instead, I discuss four issues that together might serve as an introduction to the philosophy of chemistry and at the same time give an idea of its scope. The four issues, which are chosen so that they build on each other and inspire further thinking, and which are necessarily a personal selection, are: What is chemistry about? Is chemistry reducible to physics? Are there fundamental limits to chemical knowledge? And is chemical research ethically neutral?
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