Form and Function: Seeing, Knowing, and Reasoning with Diagrams in the Practice of Science
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Form and Function: Seeing, Knowing, and Reasoning with Diagrams in the Practice of Science by Ari Bakst Gross A thesis submitted in conformity with the requirements for the degree of PhD Institute for the History and Philosophy of Science and Technology University of Toronto © Copyright by Ari Gross 2013 Form and Function: Seeing, Knowing, and Reasoning with Diagrams in the Practice of Science Abstract Form and Function: Seeing, Knowing, and Reasoning with Diagrams in the Practice of Science Ari Bakst Gross Doctor of Philosophy Institute for the History and Philosophy of Science University of Toronto 2013 Abstract In virtue of what do scientific diagrams acquire their epistemic legitimacy? Which factors serve to validate schematic visual representations, rendering them useful and accepted components of scientific practice? This thesis addresses the epistemic legitimacy of scientific diagrams by investigating a variety of diagrams whose referents are “invisible”, that is, whose targets either cannot be seen, lack physical form, or have no material analogue. In focusing on such images, we shall gain insight into the factors that shape the forms that practicing scientists give to their diagrams and shed light on contemporary issues in the philosophy of scientific models and representations. ii Form and Function: Seeing, Knowing, and Reasoning with Diagrams in the Practice of Science Abstract In this work, common factors underscoring the epistemic legitimacy of scientific diagrams are identified through three in-depth historical case studies. First, we consider several diagrammatic approaches to visualizing chemical structure that emerged around the 1860s, especially the competing approaches of August Kekulé and Alexander Crum Brown, and investigate the factors that led to the enduring success of Crum Brown’s visual representations and the corresponding abandonment of Kekulé’s. Second, we examine a spectrum of stereochemical diagrams and material models produced from the 1870s to the early 20th century, particularly those produced by J. H. van ‘t Hoff, and consider the factors that determined the forms given to representations of three-dimensional structures of chemical compounds. Third, we explore the diagrammatic approaches taken by physicist Richard Feynman in his mid-20th century lectures on quantum electrodynamics, paying close attention to his diagrams’ stylistic commonalities and dissimilarities as well as their ability to mediate between various aspects of the practice of physics. Finally, this thesis concludes by considering several common factors regarding the epistemic legitimacy of scientific diagrams that can be identified in these case studies, including the importance of a bijective relationship between scientists’ understanding of their diagrams and of their diagrams’ referents, the utility of diagrams for productively reasoning about their referents, and ability of certain diagrams to reduce scientists’ cognitive burden, especially through visual similarities. These factors serve to unite divergent approaches to the philosophy of scientific models and representation and reorient contemporary debates concerning representation towards an integrated historical-philosophical methodology. iii Form and Function: Seeing, Knowing, and Reasoning with Diagrams in the Practice of Science Acknowledgments Acknowledgments For their endless support, assistance, and insight, I offer boundless thanks to my supervisor, Chen-Pang Yeang, and to my committee, David Kaiser and Brian Baigrie. Additional thanks to Craig Fraser and Joseph Berkovitz, who participated in the defense of this dissertation. I am also deeply indebted to the Institute for the History and Philosophy of Science and Technology (IHPST), an institution which has dominated my life for the past six years both intellectually and socially. Special thanks to Denise Horsley and Muna Salloum, to all of the IHPST administration, and, of course, to my fellow colleagues, who have remain the heart and soul of the IHPST. Many thanks to the Chemical Heritage Foundation, of which I had the privilege of being a Fellow for three months. Further thanks to Sam Schweber, Alan Rocke, Peter Ramberg, Christopher Ritter, Adrian Wüthrich, and Agnes Bolinska for sharing their thoughts, advice, and research. Funding for this research was provided by Social Sciences and Humanities Research Council of Canada, the Institute for the History and Philosophy of Science and Technology, the University of Toronto School of Graduate Studies, and the Chemical Heritage Foundation. Finally, thanks to Candice Fong for her support, understanding, and love, and to Lydia Fong Gross, the greatest daughter one could ever wish for. iv Form and Function: Seeing, Knowing, and Reasoning with Diagrams in the Practice of Science Table of Contents Table of Contents Acknowledgments ........................................................................................................................... iv Table of Contents ............................................................................................................................. v 1 Introduction ............................................................................................................................... 1 1.1 Introducing scientific visual representations ...................................................................... 1 1.2 Two distinct approaches to scientific visual representations: histories of images and the philosophy of representation ....................................................................................... 3 1.3 Setting the stage: the semantic view and the epistemic legitimacy of scientific representations ................................................................................................................... 7 1.3.1 Structural and functional approaches to scientific representation and modeling ............................................................................................................... 15 1.4 Plan of the work ................................................................................................................ 17 2 Kekulé’s and Crum Brown’s Visual Representations of Structural Chemical Compounds ...... 20 2.1 Introduction ...................................................................................................................... 20 2.2 Chemical structure and organic chemistry in the mid-19th century ................................. 23 2.3 Kekulé’s “sausage diagrams” ............................................................................................ 27 2.3.1 “Two-dimensional” sausage diagrams: beyond linearity ..................................... 41 2.4 Crum Brown’s structural formulas .................................................................................... 50 2.4.1 Crum Brown’s diagrams and alternative atomicity .............................................. 55 2.4.2 Crum Brown’s diagrams, beyond his thesis .......................................................... 56 2.5 Crum Brown’s critiques of Kekulé’s diagrams .................................................................. 60 2.5.1 Kekulé and Crum Brown’s visual representations of glycolic acid ....................... 60 2.5.2 Crum Brown’s critique of Kekulé’s doubly-depicted alcohol................................ 63 2.6 Other chemists’ adoptions of Crum Brown’s graphical approach .................................... 67 v Form and Function: Seeing, Knowing, and Reasoning with Diagrams in the Practice of Science Table of Contents 2.7 Kekulé’s skeletal models and diagrams ............................................................................ 76 2.8 Analysis and Conclusions: Kekulé, Crum Brown, and diagrammatic desiderata .............. 87 3 Stereochemical Visual Representations ................................................................................... 93 3.1 Introduction ...................................................................................................................... 93 3.1.1 Introducing stereochemistry ................................................................................ 95 3.2 J. H. Van ‘t Hoff ............................................................................................................... 102 3.2.1 Introducing Van ‘t Hoff’s diagrams and models ................................................. 105 3.2.2 Van ‘t Hoff’s diagrams after the Voorstel: La Chimie Dans L’espace and other works ................................................................................................................... 111 3.2.3 Geometrical asymmetry and optical activity in La Chimie ................................. 120 3.2.4 Back to benzene: Van ‘t Hoff and the structure of aromatic compounds .......... 128 3.3 Van ‘t Hoff’s molecular models ....................................................................................... 139 3.4 The fate of tetrahedral diagrams .................................................................................... 148 3.4.1 Wislicenus’ reactive tetrahedra .......................................................................... 148 3.5 The limited persistence of tetrahedral diagrams and models........................................ 154 3.6 Stereospatial skeletal representations: Baeyer’s strain theory and Mohr’s conformational analysis .................................................................................................. 165 3.7 Analysis and Conclusions: the surprising significance