Vera Maximilia Straetmanns

In this chapter, we discuss the role of evolutionary theory—especially Darwinism—during the institutionalization of theoretical biology in the early twentieth century. During this time, theoretical biologists strived to establish a new theoretical framework for biology. Rather than unifying biological phenomena under Darwin’s theory of natural selection, they aimed to establish a philosophical framework that could overcome the vitalism-mechanism divide and counteract disciplinary fragmentation and specialization. Their accounts ultimately turned out to be in line or in conflict with Darwin’s theory, but discussing Darwinism was not the driving force to develop them. Our historical narrative is based on a twofold approach: First, we conduct a Digital Humanities analysis of central publications in the field; second, we discuss in detail how influential theoretical biologists, especially the zoologist Julius Schaxel, shaped “synthesis discourses.” We show that theoretical biologists objected to evolutionary theories due to their underlying philosophies: mechanism and materialism (for Darwinism) and vitalism (for Lamarckism). Their new philosophical synthesis did not directly aim to reject Darwinian principles like natural selection nor to establish an evolutionary synthesis through population genetics. This makes it necessary to deconstruct established periodizations of past evolutionary theorizing, as such philosophically minded unification attempts neither directly contributed to the “eclipse of Darwinism” nor to the emergence of the Modern Synthesis. Finally, we argue that a stronger engagement with so-far “eclipsed” debates in early twentieth century theoretical biology can help casting a light on past and present developments in evolutionary theory.

Agnes Arber (1879–1960) was a British plant morphologist, historian of botany, and philosopher of biology. Though now largely forgotten, her work offers valuable insights into morphological as well as philosophical issues. This paper focuses on Arber’s work on teleology in plants. After providing a brief overview of her life and distinct style of work, two notions of teleology are presented, which become apparent in Arber’s morphological and philosophical work. The first notion, labeled _final teleology_, is based on Aristotle’s final cause and deals with adaptation-based explanations in biology. The second is labeled _formal teleology_. It is grounded in the Aristotelian formal cause and deals with the inherent directiveness of developing structures and the actualization of potentialities in organisms and their parts. Whereas Arber showed a reserved and skeptical attitude towards final teleology, she was very sympathetic to formal teleology, building her general morphological framework on it. Two examples from Arber’s work are then given, which illustrate how formal teleology informed her theorizing: the partial-shoot theory of the leaf, and parallelism in evolution as a counter-proposal to natural selection. Finally, Arber’s teleological interpretation of plant morphology is historically contextualized and connected to recent research developments in evolutionary biology and plant morphology.