Interpreting the History of Evolutionary Biology through a Kuhnian Prism: Sense or Nonsense? Koen B. Tanghe Department of Philosophy and Moral Sciences, Universiteit Gent, Belgium Lieven Pauwels Department of Criminology, Criminal Law and Social Law, Universiteit Gent, Belgium Alexis De Tiège Department of Philosophy and Moral Sciences, Universiteit Gent, Belgium Johan Braeckman Department of Philosophy and Moral Sciences, Universiteit Gent, Belgium Traditionally, Thomas S. Kuhn’s The Structure of Scientific Revolutions (1962) is largely identified with his analysis of the structure of scientific revo- lutions. Here, we contribute to a minority tradition in the Kuhn literature by interpreting the history of evolutionary biology through the prism of the entire historical developmental model of sciences that he elaborates in The Structure. This research not only reveals a certain match between this model and the history of evolutionary biology but, more importantly, also sheds new light on several episodes in that history, and particularly on the publication of Charles Darwin’s On the Origin of Species (1859), the construction of the modern evolutionary synthesis, the chronic discontent with it, and the latest expression of that discon- tent, called the extended evolutionary synthesis. Lastly, we also explain why this kind of analysis hasn’t been done before. We would like to thank two anonymous reviewers for their constructive review, as well as the editor Alex Levine. Perspectives on Science 2021, vol. 29, no. 1 © 2021 by The Massachusetts Institute of Technology https://doi.org/10.1162/posc_a_00359 1 Downloaded from http://www.mitpressjournals.org/doi/pdf/10.1162/posc_a_00359 by guest on 30 September 2021 2 Evolutionary Biology through a Kuhnian Prism 1. Introduction About a century ago, the American anthropologist Franz Boas (1911) ex- plained that our experiences of the world are infinitely diverse and that, con- sequently, reductive linguistic categorization is necessary in order to be able to think and talk about it. Evidently, our categorization of the world doesn’t end there but is supplemented with second-order, cognitive abstractions and categorizations. Examples are typologies of earthquakes or human diseases and developmental schemes of civilizations or sciences. An example of a developmental scheme of sciences is that of the Canadian sociologist and historian of science Yves Gingras (1991). He distinguishes three steps in the sociological development of scientific disciplines: the emergence of a new prac- tice, its institutionalization, and the shaping of a social identity. Méthot (2016) uses this simple tripartite framework in his analysis of the history and histori- ography of virology. Here, we want to apply the developmental model of sciences that Thomas S. Kuhn elaborated in his The Structure of Scientific Revolutions (1962) to the history of evolutionary biology. Of course, as its title indicates, scientific revolutions form the main part of Kuhn’s book. Or, as he put it himself (Kuhn [1959] 1977, p. 226): the emphasis of Structure is on “the importance to scientific development of ‘revolutions’.” It cannot be denied, though, that it also offers a “schematic description of scientificdevelopment” (Kuhn 1962, p. 160) or of “the essential structure of a science’s continuing evolution” (Kuhn 1962, p. 160) and that his analysis of the structure of scientific revolutions merely forms a part of that broader developmental scheme.1 In a first section (section 2), we argue that this scheme can be discerned in the history of evolutionary biology, albeit only partly: on the one hand, it encompasses a phase that cannot, or not yet, be discerned in the history of evolutionary biology (a Kuhnian revolution), on the other hand, that history started (in earnest) with a very important achievement (the publication of Charles Darwin’s On the Origin of Species in 1859) that, strangely, doesn’t really fit in Kuhn’s original scheme. Our revelation of this imperfect match between Kuhn’s developmental model and the standard historiography of evolutionary biology is, in itself, a not very relevant or maybe even trivial exercise in the philosophy of the history of science.2 Ouranalysisdoesn’t end there, though: as 1. Greene points out that Structure was the first attempt to “construct a generalized pic- ture of the process by which a science is born and undergoes change and development (…)”([1971] 1981, p. 30). 2. The standard historiography of evolutionary biology is also known as ‘Synthesis His- toriography’ since it tells the story of this history in ways that “turn out right for the Modern Synthesis” (Stoltzfus 2017, p. 4). Stoltzfus and Cable (2014) develop an alternative historiog- raphy. They claim that a Mendelian-Mutationist synthesis emerged in the early twentieth cen- tury and that contemporary evolutionary thinking seems closer to this synthesis than to the Downloaded from http://www.mitpressjournals.org/doi/pdf/10.1162/posc_a_00359 by guest on 30 September 2021 Perspectives on Science 3 we will show in section 3, a Kuhnian x-ray scan of the history of evolutionary biology yields several new insights in that history. Lastly, section 4 is dedicated to explaining why the history of evolutionary biology hasn’t been interpreted in terms of Kuhn’s developmental scheme before. 2. An Imperfect Match The broad outline of Kuhn’s scheme is well known: a pre-paradigmatic phase in the historical development of a science is followed by the emergence of a paradigm, a normal science phase and a phase of extraordinary science and rev- olution. The main distinction in The Structure is that between this revolutionary phase and normal science. This is the ‘essential tension’ in scientific research (see, e.g., Marcum 2015, pp. 46–7orBird2000,ch.2).Thepre-paradigmatic phase, by contrast, is only briefly discussed in chapter two, “The Route to Normal Science.”3 It is characterized by the coexistence of a number of com- peting schools which each interpret a natural phenomenon in a different way. The bickering of adherents of these different pre-paradigmatic schools is not entirely fruitless, though. They are genuine scientists, but much of their efforts are devoted to combatting and trying to convince opponents, rather than to cumulative research. A normal science phase starts with the emergence of a paradigm: a new theoretical framework that inspires the work of a majority of the practitioners of a specific discipline because it solves important problems and offers research opportunities and particularly because it provides them with standard exam- ples of good scientific practice. Or, as Kuhn put it himself: [These works were] sufficiently unprecedented to attract an enduring group of adherents away from competing modes of scientific activity. Simultaneously, it was sufficiently open-ended to leave all sorts of problems for the redefined group of practitioners to resolve. Achievements that share these two characteristics I shall henceforth modern evolutionary synthesis. Consequently, it is the Mendelian-Mutationist synthesis that should be considered as the foundation of modern evolutionary biology. For another example of a criticism of the Synthesis-dominated historiography of evolutionary biology, see Amundson (2005). 3. In this chapter, Kuhn points out that the study of light and of electricity was charac- terized by fundamental disagreements before the publication of the work of, respectively, Isaac Newton and Benjamin Franklin (and his immediate successors). These disagreements also characterize (1) “the study of motion before Aristotle and of statics before Archimedes, the study of heat before Black, of chemistry before Boyle and Boerhaave, and of historical geology before Hutton” (Kuhn 1962, p. 15) and (2) the study of life phenomena before the appearance of unspecified biologists. He is less certain about the social sciences: “it remains an open ques- tion what parts of social science have yet acquired such paradigms at all. History suggests that the road to a firm research consensus is extraordinarily arduous” (Kuhn 1962, p. 15). Downloaded from http://www.mitpressjournals.org/doi/pdf/10.1162/posc_a_00359 by guest on 30 September 2021 4 Evolutionary Biology through a Kuhnian Prism refer to as ‘paradigms,’ a term that relates closely to ‘normal science’. By choosing it, I mean to suggest that some accepted examples of actual scientific practice (…) provide models from which spring particular coherent traditions of scientific research (1962, p. 10).4 This paradigm concept was inspired by the fundamental difference between internally divided social scientists and more united practitioners of the natural sciences that Kuhn noticed during a stay in 1958–1959 at the Center of Advanced Studies in the Behavioral Sciences (see Kuhn 1962, p. x). How- ever, by 1974, he had changed this origin story of his central term. It was now not coined to account for the difference between the social sciences and the natural sciences but, more in general, “to account for the consensus necessary among scientists in a specialty in order for them to pursue their research goals effectively” (Wray 2011, p. 49). Also, Kuhn now claimed that it was “the sense of ‘paradigm’ as standard example that led originally to [his] choice of that term” (Kuhn 1977, p. xviii): a group’s unproblematic and common or paradigmatic conduct of research was facilitated by those shared examples of successful practice (i.e., paradigms in the specific meaning of exemplars). They could provide what a paradigmatic group “lacked in rules” (Kuhn [1974] 1977, p. 318).5 In the postscript to the second edition of Structure, he had already claimed that the term paradigm had been inspired by the exemplar component “of a group’s shared commitments” (Kuhn [1962] 1970, p. 187). He introduced this distinction between exemplars and a group’s “shared commitments” (i.e., “the entire constellation of beliefs, values, techniques and so on shared by 4. This is also how he defines paradigms in the preface of Structure: paradigms are “univer- sally recognized scientificachievementsthatforatimeprovidemodelproblemsandsolutionsto a community of practitioners” (p.