Philosophy of Chemistry

Philosophy of Chemistry by Eric Scerri Of course, the field of compu- hen I push my hand down onto my desk it tational quantum chemistry, does not generally pass through the which Dirac and other pioneers Wwooden surface. Why not? From the per- of quantum mechanics inadver- spective of physics perhaps it ought to, since we are tently started, has been increas- told that the atoms that make up all materials consist ingly fruitful in modern mostly of empty space. Here is a similar question that chemistry. But this activity has is put in a more sophisticated fashion. In modern certainly not replaced the kind of physics any body is described as a superposition of chemistry in which most practitioners are engaged. many wavefunctions, all of which stretch out to infin- Indeed, chemists far outnumber scientists in all other ity in principle. How is it then that the person I am fields of science. According to some indicators, such as talking to across my desk appears to be located in one the numbers of articles published per year, chemistry particular place? may even outnumber all the other fields of science put together. If there is any sense in which chemistry can The general answer to both such questions is that be said to have been reduced then it can equally be although the physics of microscopic objects essen- said to be in a high state of "oxidation" regarding cur- tially governs all of matter, one must also appeal to rent academic and industrial productivity. the laws of chemistry, material science, biology, and Starting in the early 1990s a group of philosophers other sciences. Chemistry for example, may be essen- and chemists with philosophical leanings began pub- tially governed by the laws of quantum mechanics, lishing articles aimed at exploring the question of the but in order to alleged reduction of chemistry. Soon thereafter the . there has been an study the nature International Society for the Philosophy of Chemistry ongoing debate about and transforma- was created. Its official journal, Foundations of tion of matter at Chemistry, has begun its fifth year of publication. just how much the appropriate Another international journal, called Hyle, also quantum mechanics chemical level, one devoted to the field, had been launched earlier on the should be deployed in needs to appeal to Internet but is now also available in paper form. laws of science There has been a good deal of interest from the the teaching of general other than just chemical education community, not surprisingly since chemistry. quantum mechan- educators regularly face philosophical choices as to ics. This realization how to best present the contents of chemistry courses that chemistry is and what kind of emphasis should be pursued. not fully "reduced" to quantum mechanics has been Returning to an earlier issue, there has been an ongo- one of the main motivations for the recent resurgence ing debate about just how much quantum mechanics in the philosophy of chemistry. should be deployed in the teaching of general chem- Before the turn of the 20th century chemistry was istry. Detailed studies on such questions are beginning at the heart of philosophical issues in science. For to emerge from work in philosophy of chemistry and example, it was almost exclusively chemists who con- are being seriously considered by educators. ducted the atomic debates that followed the influen- But philosophers of chemistry are also concerned tial work of John Dalton. While some of them with many other issues beyond the role of quantum regarded atoms as entities that actually existed, oth- mechanics. Philosophers of science have realized for ers thought about them as mere convenient fictions. some time that there has been too much focus on But following the discovery of radioactivity and the purely theoretical and logical aspects of science. birth of quantum theory, the atom was snatched away There has been a gradual turn towards the study of from the chemist and the philosophical focus scientific models and approximations as well as the switched to physics, which had by this time also expe- nature of semi-empirical methods and instrumental rienced the Einsteinian revolution in the study of techniques. In all these areas chemistry has begun to space and time. Chemists began to be seen as people provide a rich selection of new case studies, especially doing applied physics. As Dirac famously claimed, all given the less deductive nature of chemical theories of chemistry had been reduced to physics and all that as compared with those of physics. remained was to clear up the details. The recent influx of philosophy into chemistry also CHEMISTRY International May-June 2003 7 Feature promises to clarify another Some chemical educators ways of producing industrial important issue in chemical edu- have even fallen prey to chemicals. The approach is essen- cation. In recent years many sci- tially a philosophical one. The ence educators, and especially the related post-modern relationship between ethics and many chemical educators, have position of relativism chemistry is being increasingly begun to support an approach without realizing that this examined by some philosophers referred to as constructivism. of chemistry. These authors correctly point out is both self-defeating and The study of visualization and that students come to chemistry essentially anti-scientific representation is another philo- classes from a wide variety of in spirit. sophical issue that has come backgrounds and with many pre- increasingly to the fore with the conceptions. They claim that it is development of chemistry and a mistake to ignore the fact that the parallel growth of computa- students have constructed their view of scientific tional power. Chemists are rather unique in frequently facts such as the nature of acids and bases to take just needing to visualize structures and entities that they one example. also know not to exist according to the dictates of But in their eagerness to embrace this admittedly physics. Atomic and molecular orbitals are a good more enlightened educational approach, some of case in point. They are used as mathematical tools in these chemical educators have unwittingly aligned quantum chemistry at all levels. Their use has been themselves with constructivist claims about the man- undeniably productive—as in the case of the ner in which mature scientific knowledge is arrived at Woodward-Hoffman rules in organic chemistry. And by mature scientists. The claim of constructivists is yet, from the perspective of quantum physics, any that scientific knowledge is somehow socially con- orbital is just a mathematical fiction devoid of any real structed rather than being discovered. The dominant existence just like the school of chemical education may therefore be on the square root of the number wrong side of the recent and notorious Science Wars minus one in mathematics. debate. Some chemical educators have even fallen But sometimes the zeal prey to the related post-modern position of relativism with which chemists like to without realizing that this is both self-defeating and embrace models and visual- essentially anti-scientific in spirit. If, as relativism izations goes a little too far. maintains, all paths of knowledge are equally valid Such was the case about three then why should anyone even want to support rela- years ago when many scien- tivism itself in favor of any other philosophical tific magazines reported the approach? claim that textbook orbitals Fortunately, articles emerging from the philosophy had been literally observed for of chemistry have now begun to challenge the confu- the first time. These excesses sion that exists among some chemical educators. The were quickly corrected in the ensuing debates might serve to distinguish between literature but the only people educational constructivism, which may be valid, from who took the trouble to do so constructivism about scientific knowledge itself, were among the more reflec- which very few scientists are willing to concede to but tive chemists and philoso- which many chemical educators seem to draw inspi- phers of chemistry. ration from. There is another reason Then there are ethical questions that inevitably sur- why philosophy of chemistry round chemical synthesis and the chemical industry in has been such a recent new- Source: Tim Lenoir, Stanford University general. As we all know chemistry receives more than comer alongside the more established study of philo- its share of the blame for the environmental ills of sophical aspects of modern physics and biology. The today. One positive response from the chemical com- reason is partly historical and partly due to the kind of munity has been the growth of the Green Chemistry systems one is dealing with in each of the three sci- initiative that aims to find environmentally friendly ences. Of course, philosophers of science have tradi- 8 CHEMISTRY International May-June 2003 Feature tionally concentrated on physics since it is the most ing of science as a whole. Seen in this way, the fundamental science. delayed emergence of philosophy of chemistry is no But fundamental does not necessarily mean more longer mysterious but may be a direct outcome of its important. This is clearly seen if one thinks of biology. frequently noted central position among the natural To living beings such as us there is an immediate sense sciences. in which biology is more relevant and more important The rising interest in the field was quite evident at than abstract theoretical physics. In the 1950s and ’60s the sixth meeting of the International Society for the philosophers of science realized that they had concen- Philosophy of Chemistry that took place at trated too much on physics and that the general prin- Georgetown University in Washington, D.C., in August ciples they had arrived at regarding the nature of 2002.

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