ABSTRACT I propose a division of the literature on natural kinds into metaphysical worries, semantic worries, and methodological worries. I argue that the latter set of worries, which concern how classification influences scientific practices, should occupy centre stage in philosophy of science discussions about natural kinds. I apply this methodological framework to the problems of classifying chemical species and nanomaterials. I show that classification in nanoscience differs from classification in chemistry because the latter relies heavily on compositional identity, whereas the (...) former must consider additional properties, namely, size, shape, and surface chemistry. I use this difference to argue for a scale-dependent theory of scientific classification. _1_ Introduction _2_ The Methodological Problem of Kinds _3_ Chemical Kindhood: Reactivity, Microstructure, and the Structure–Property Paradigm _4_ Scale-Dependence and Nanoscale Kinds _5_ Conclusion. (shrink)

Recently, macroscopic accounts of chemical kind individuation have been proposed as alternatives to the microstructural essentialist account advocated by Kripke, Putnam, and others. These accounts argue that individuation of chemical kinds is based on macroscopic criteria such as reactivity or thermodynamics, and they challenge the essentialism that grounds the Kripke-Putnam view. Using a variety of chemical examples, I argue that microstructure grounds these macroscopic accounts, but that this grounding need not imply essentialism. Instead, kinds are individuated on the basis of (...) similarity of reactivity between substances, and microstructure explains similarity of reactivity. (shrink)

Summary Linus Pauling played a key role in creating valence-bond theory, one of two competing theories of the chemical bond that appeared in the first half of the 20th century. While the chemical community preferred his theory over molecular-orbital theory for a number of years, valence-bond theory began to fall into disuse during the 1950s. This shift in the chemical community's perception of Pauling's theory motivated Pauling to defend the theory, and he did so in a peculiar way. Rather than (...) publishing a defence of the full theory in leading journals of the day, Pauling published a defence of a particular model of the double bond predicted by the theory in a revised edition of his famous textbook, The Nature of the Chemical Bond. This paper explores that peculiar choice by considering both the circumstances that brought about the defence and the mathematical apparatus Pauling employed, using new discoveries from the Ava Helen and Linus Pauling Papers archive. (shrink)

Nanosynthesis forces a reevaluation of received views on scientific explanation. I discuss the synthesis of anisotropic metal nanoparticles, a typical nanosynthesis research program, in order to demonstrate the failure of standard philosophical accounts of explanation to capture the dynamics of information exchange in synthetic sciences. I argue that using the language of effective heuristics, coupled with attention to changes in the meanings of concepts across different length scales, is a more promising means of capturing how information is obtained from the (...) study of nanosynthesis systems. (shrink)

Sometimes the right book finds you at the right time, and it shifts your perception of a familiar subject just a little, just enough to make a difference. It reminds you of something important you haven’t thought of in a while, or it shows you a new way of looking at and interacting with the world. Last winter, for me, that book was The Disappearing Spoon, by Sam Kean. I heard a very fuzzy description of the book at a holiday (...) party, something about the periodic table and political history. As someone eternally interested in chemistry and its impact on society at large, I was intrigued. (shrink)