Adaptable frameworks: Toward a unified theory of individuality in diverse evolutionary systems

This thesis is about individuality in Darwinian systems. It puts four contemporary frameworks in discussion, ultimately combining Godfrey-Smith’s (2009) view of Darwinian populations with Clarke’s (2011) account of the functions of individuality to develop an initial proposal for the identification of evolutionary individuality. This proposal has significant flexibility to account for the diversity of Darwinian phenomena while also being anchored to specified processes of individuation such that the proposal can generate informative explanations of evolutionary phenomena. Evolutionary systems are often described in terms of individuated populations of entities. However, there is substantial debate about how to systematically individuate these systems given their diversity and given apparent transitions in individuality across scales—from the molecular to the multicellular—over time.

Through an analysis of gene and multilevel selection, I will argue that explanations that parse hierarchical systems into entities at different scales are predictively equivalent. This metaphysical complexity makes the identification of individuality more difficult, as we need other criteria than predictive validity to prefer descriptions over one another. I argue that gene and multilevel selection attempt to prefer certain descriptions despite this equivalence of explanations. They justify this by an appeal to entities with a significant relationship to features of the Darwinian process, which enables them to capture that process more powerfully. I will show that both are limited as the features they identify are either too specific to be generalisable or not specific enough to satisfactorily differentiate phenomena. I argue that Godfrey-Smith’s (2009) account of paradigmatic reproduction has the potential to avoid these extremes. Its robust account of paradigmatic Darwinian systems allows his account to generate descriptions that are explanatorily powerful for a wide range of evolutionary phenomena. However, I also show how this potential wide applicability is limited by his focus on paradigmatic reproduction. Finally, I introduce Clarke’s (2011) account of functions of individuation to argue that Clarke’s and PGS’s accounts are substantially compatible. Combining them provides an account flexible enough for diverse systems while still identifying concrete processes. This proposal has the potential to be a significant tool for expanding our understanding of the individuation of Darwinian systems.