Sewall Wright first encountered the complex systems characteristic of gene combinations while a graduate student at Harvard's Bussey Institute from 1912 to 1915. In Mendelian breeding experiments, Wright observed a hierarchical dependence of the organism's phenotype on dynamic networks of genetic interaction and organization. An animal's physical traits, and thus its autonomy from surrounding environmental constraints, depended greatly on how genes behaved in certain combinations. Wright recognized that while genes are the material determinants of the animal phenotype, operating with great (...) regularity, the special nature of genetic systems contributes to the animal phenotype a degree of spontaneity and novelty, creating unpredictable trait variations by virtue of gene interactions. As a result of his experimentation, as well as his keen interest in the philosophical literature of his day, Wright was inspired to see genetic systems as conscious, living organisms in their own right. Moreover, he decided that since genetic systems maintain ordered stability and cause unpredictable novelty in their organic wholes (the animal phenotype), it would be necessary for biologists to integrate techniques for studying causally ordered phenomena (experimental method) and chance phenomena (correlation method). From 1914 to 1921 Wright developed his "method of path coefficient" (or "path analysis"), a new procedure drawing from both laboratory experimentation and statistical correlation in order to analyze the relative influence of specific genetic interactions on phenotype variation. In this paper I aim to show how Wright's philosophy for understanding complex genetic systems (panpsychic organicism) logically motivated his 1914-1921 design of path analysis. (shrink)

Sewall Wright first encountered the complex systems characteristic of gene combinations while a graduate student at Harvard's Bussey Institute from 1912 to 1915. In Mendelian breeding experiments, Wright observed a hierarchical dependence of the organism's phenotype on dynamic networks of genetic interaction and organization. An animal's physical traits, and thus its autonomy from surrounding environmental constraints, depended greatly on how genes behaved in certain combinations. Wright recognized that while genes are the material determinants of the animal phenotype, operating with great (...) regularity, the special nature of genetic systems contributes to the animal phenotype a degree of spontaneity and novelty, creating unpredictable trait variations by virtue of gene interactions. As a result of his experimentation, as well as his keen interest in the philosophical literature of his day, Wright was inspired to see genetic systems as conscious, living organisms in their own right. Moreover, he decided that since genetic systems maintain ordered stability and cause unpredictable novelty in their organic wholes, it would be necessary for biologists to integrate techniques for studying causally ordered phenomena and chance phenomena. From 1914 to 1921 Wright developed his "method of path coefficient", a new procedure drawing from both laboratory experimentation and statistical correlation in order to analyze the relative influence of specific genetic interactions on phenotype variation. In this paper I aim to show how Wright's philosophy for understanding complex genetic systems logically motivated his 1914-1921 design of path analysis. (shrink)

The aim of this virtual special issue is to bring together philosophical and historical perspectives to address long-standing issues in the interpretation, utility, and impacts of quantitative genetics methods and findings. Methodological approaches and the underlying scientific understanding of genetics and heredity have transformed since the field's inception. These advances have brought with them new philosophical issues regarding the interpretation and understanding of quantitative genetic results. The contributions in this issue demonstrate that there is still work to be done integrating (...) old and new methodological and conceptual frameworks. In some cases, new results are interpreted using assumptions based on old concepts and methodologies that need to be explicitly recognised and updated. In other cases, new philosophical tools can be employed to synthesise historical quantitative genetics work with modern methodologies and findings. This introductory article surveys three general themes that have dominated philosophical discussion of quantitative genetics throughout history: (1) how methodologies have changed and transformed our knowledge and interpretations; (2) whether or not quantitative genetics can offer explanations relating to causation and prediction; and (3) the importance of defining the phenotypes under study. We situate the contributions in this virtual special issue within a historical framework addressing these three themes. (shrink)

This paper challenges the common assumption that some phenotypic traits are quantitative while others are qualitative. The distinction between these two kinds of traits is widely influential in biological and biomedical research as well as in scientific education and communication. This is probably due to both historical and epistemological reasons. However, the quantitative/qualitative distinction involves a variety of simplifications on the genetic causes of phenotypic variability and on the development of complex traits. Here, I examine three cases from the life (...) sciences that show inconsistencies in the distinction: Mendelian traits, Mendelian diseases, and polygenic mental disorders. I show that these traits can be framed both quantitatively and qualitatively depending, for instance, on the methods through which they are investigated and on specific epistemic purposes. This suggests that the received view of quantitative and qualitative traits has a limited heuristic power—limited to some local contexts or to the specific methodologies adopted. Throughout the paper, I provide directions for framing phenotypes beyond the quantitative/qualitative distinction. I conclude by pointing at the necessity of developing a principled characterisation of what phenotypic traits, in general, are. (shrink)

I call an experiment “crucial” when it makes possible a decisive choice between conflicting hypotheses. Joharmsen's selection for size and weight within pure lines of beans played a central role in the controversy over continuity or discontinuity in hereditary change, often known as the Biometrician-Mendelian controversy. The “crucial” effect of this experiment was not an instantaneous event, but an extended process of repeating similar experiments and discussing possible objections. It took years before Johannsen's claim about the genetic stability of pure (...) lines was accepted as conclusively demonstrated by the community of geneticists. The paper also argues that crucial experiments thus interpreted contradict certain ideas about the underdetermination of theories by facts and the theory-ladenness of facts which have been influential in recent history and sociology of science. The acceptance of stability in the pure lines did not rest on prior preference for continuity or discontinuity. And this fact permitted a final choice between the two theories. When such choice is characterized as “decisive” or “final”, this is not meant in an absolute philosophical sense. What we achive in these cases is highly reliable empirical knowledge. The philosophical possibility of drawing (almost) any conclusion in doubt should be distinguished from reasonable doubt in empirical science. (shrink)

Fisher’s ‘fundamental theorem of natural selection’ is notoriously abstract, and, no less notoriously, many take it to be false. In this paper, I explicate the theorem, examine the role that it played in Fisher’s general project for biology, and analyze why it was so very fundamental for Fisher. I defend Ewens and Lessard in the view that the theorem is in fact a true theorem if, as Fisher claimed, ‘the terms employed’ are ‘used strictly as defined’. Finally, I explain the (...) role that projects such as Fisher’s play in the progress of scientific inquiry. (shrink)

Fisher’s ‘fundamental theorem of natural selection’ is notoriously abstract, and, no less notoriously, many take it to be false. In this paper, I explicate the theorem, examine the role that it played in Fisher’s general project for biology, and analyze why it was so very fundamental for Fisher. I defend Ewens and Lessard in the view that the theorem is in fact a true theorem if, as Fisher claimed, ‘the terms employed’ are ‘used strictly as defined’. Finally, I explain the (...) role that projects such as Fisher’s play in the progress of scientific inquiry. (shrink)

This article scrutinizes in detail much of the extant historiography on the controversy between biometricians and Mendelians, considering in particular how this controversy is related to the evolutionary synthesis. While the historiographic critique concentrates on William Provine’s standard account, it also extends to the proposal by Donald MacKenzie and Barry Barnes. What Provine and these sociologists of scientific knowledge have in common is a set of unquestioned assumptions about the nature of Darwinism, about William Bateson’s anti-Darwinism, and about the very (...) idea of an evolutionary “synthesis.” While these assumptions make for a compelling history of the synthesis, they engender an endemically asymmetrical perspective and bias historiography toward the mere confirmation of antecedent expectations, which renders the years from 1859 to 1929 an age of ignorance and misunderstanding. In contrast, a return to what was probably the original meaning of evolutionary “synthesis” allows for a symmetrical account. It yields an appreciation of the positive contributions made both by Mendelians and biometricians to the gradual development of Darwinism. The article concludes with a synopsis of this alternative account. (shrink)

The controversy between Biometricians and Mendelians has been called an inexplicable embarrassment since it revolved around the mistaken identification of Mendelian genetics with non-Darwinian saltationism, a mistake traced back to the non-Darwinian William Bateson, who introduced Mendelian analysis to British science. The following paper beings to unravel this standard account of the controversy by raising a simple question: Given that Bateson embraced evolution by natural selection and that he studied the causes of variation within a broadly Darwinian framework of problems (...) and questions, how are we to understand the claim that he was a non-Darwinian? A brief survey of possible responses to this question is followed by an alternative proposal: the controversy will be considered as a struggle among Darwinians about the future course of Darwinism. On this account, Darwin's own work led to the juncture at which Mendelians and Biometricians parted company, indeed, the Origin itself prepared the divergent methodological stances subsequently adopted by Bateson and his antagonists. The inexplicable embarrassment is dissolved through the parsimonious reconstruction of the profound substantive conflict between Biometricians and Mendelians as a chapter in the articulation and differentiation of the Darwinian research programme. (shrink)

The debate between the Mendelians and the (largely Darwinian) biometricians has been referred to by R. A. Fisher as ‘one of the most needless controversies in the history of science’ and by David Hull as ‘an explicable embarrassment’. The literature on this topic consists mainly of explaining why the controversy occurred and what factors prevented it from being resolved. Regrettably, little or no mention is made of the issues that figured in its resolution. This paper deals with the latter topic (...) and in doing so reorients the focus of the debate as one between Karl Pearson and R. A. Fisher rather than between the biometricians and the Mendelians. One reason for this reorientation is that Pearson's own work in 1904 and 1909 suggested that Mendelism and biometry could, to some extent, be made compatible, yet he remained steadfast in his rejection of Mendelism. The interesting question then is why Fisher, who was also a proponent of biometric methods, was able to synthesise the two traditions in a way that Pearson either could not or would not. My answer to this question involves an analysis of the ways in which different kinds of assumptions were used in modelling Mendelian populations. I argue that it is these assumptions, which lay behind the statistical techniques of Pearson and Fisher, that can be isolated as the source of Pearson's rejection of Mendelism and Fisher's success in the synthesis. (shrink)

I evaluate the plausibility of explanatory elitism, the view that a good scientific explanation of an outcome will show that it was highly probable. I consider an argument from Michael Strevens that elitism is the only view that can account for the historical acceptance of probabilistic theories in physics. I argue that biology provides better test cases for evaluating elitism and conclude that theories in that domain were favored in virtue of conferring correct, and not necessarily high, probabilities on outcomes.

The article reevaluates the reception of Mendelism in France, and more generally considers the complex relationship between Mendelism and plant breeding in the first half on the 20th century. It shows on the one side that agricultural research and higher education institutions have played a key role in the development and institutionalization of genetics in France, whereas university biologists remained reluctant to accept this approach on heredity. But on the other side, plant breeders, and agricultural researchers, despite an interest in (...) Mendelism, never came to see it as the breeders' panacea, and regarded it instead as of only limited value for plant breeding. I account for this judgment in showing that the plant breeders and Mendelism designed two contrasting kinds of experimental systems and inhabited distinct experimental cultures. While Mendelian geneticists designed experimental systems that allowed the production of definite ratios of different forms that varied in relation to a few characters, plant breeders' experimental systems produced a wide range of variation, featuring combinations between hundreds of traits. Rather than breaking this multiple variation down into simple elements, breeders designed and monitored a genetic lottery. The gene was a unit in a Mendelian experimental culture, an "epistemic thing" as Rheinberger put it, that could be grasped by means of statistical regularities, but it remained of secondary importance for French plant breeders, for whom the strain or the variety -- not the gene -- was the fundamental unit of analysis and manipulation. (shrink)

This paper contributes to the ongoing reassessment of the controversy between William Bateson and Karl Pearson by characterising what we call “Batesonian Mendelism” and “Pearsonian biometry” as coherent and competing scientific outlooks. Contrary to the thesis that such a controversy stemmed from diverging theoretical commitments on the nature of heredity and evolution, we argue that Pearson’s and Bateson’s alternative views on those processes ultimately relied on different appraisals of the methodological value of the statistical apparatus developed by Francis Galton. Accordingly, (...) we contend that Bateson’s belief in the primacy of cross-breeding experiments over statistical analysis constituted a minimal methodological unifying condition ensuring the internal coherence of Batesonian Mendelism. Moreover, this same belief implied a view of the study of heredity and evolution as an experimental endeavour and a conception of heredity and evolution as fundamentally discontinuous processes. Similarly, we identify a minimal methodological unifying condition for Pearsonian biometry, which we characterise as the view that experimental methods had to be subordinate to statistical analysis, according to methodological standards set by biometrical research. This other methodological commitment entailed conceiving the study of heredity and evolution as subsumable under biometry and primed Pearson to regard discontinuous hereditary and evolutionary processes as exceptions to a statistical norm. Finally, we conclude that Batesonian Mendelism and Pearsonian biometry represented two potential versions of a single genetics-based evolutionary synthesis since the methodological principles and the phenomena that played a central role in the former were also acknowledged by the latter—albeit as fringe cases—and conversely. (shrink)

Fisher’s ‘fundamental theorem of natural selection’ is notoriously abstract, and, no less notoriously, many take it to be false. In this paper, I explicate the theorem, examine the role that it played in Fisher’s general project for biology, and analyze why it was so very fundamental for Fisher. I defend Ewens (1989) and Lessard (1997) in the view that the theorem is in fact a true theorem if, as Fisher claimed, ‘the terms employed’ are ‘used strictly as defined’ (1930, p. (...) 38). Finally, I explain the role that projects such as Fisher’s play in the progress of scientific inquiry. (shrink)

The so-called "biometric-Mendelian controversy" has received much attention from science studies scholars. This paper focuses on one scientist involved in this debate, Arthur Dukinfield Darbishire, who performed a series of hybridization experiments with mice beginning in 1901. Previous historical work on Darbishire's experiments and his later attempt to reconcile Mendelian and biometric views describe Darbishire as eventually being "converted" to Mendelism. I provide a new analysis of this episode in the context of Darbishire's experimental results, his underlying epistemology, and his (...) influence on the broader debate surrounding the rediscovery and acceptance of Mendelism. I investigate various historiographical issues raised by this episode in order to reflect on the idea of "conversion" to a scientific theory. Darbishire was an influential figure who resisted strong forces compelling him to convert prematurely due to his requirements that the new theory account for particularly important anomalous facts and answer the most pressing questions in the field. (shrink)