Classical evolutionary genetics is characterised for endorsing a population kind of thinking and for reducing organisms to a sum of their traits. In this framework, fitness is typically reduced to the quantitative study of the adaptive value that traits, and ultimately, genes, confer to the organism. This reductionist approach has been questioned by other branches of contemporary evolutionary biology, such as evolutionary developmental biology (evo-devo), which highlights the role that organisms play in evolutionary explanations. In this project, I want to explore the metaphysical implications and consequences of this organismal shift from the point of view of population and typological thinking. In particular, I aim at studying whether the explanatory notions assumed in evolutionary biology, and specially the use of dispositions, need to be altered or reviewed in order to make a better sense of the new organismal approach. In evo-devo, evolutionary dispositions, such as evolvability, modularity or plasticity, tend to be attributed to types of organisms rather than to individuals or populations of them (Austin 2017, Nuño de la Rosa and Villegas 2019). Yet, within the metaphysical literature, it is generally assumed that dispositions are predicated of tokens and not of types, since only token dispositions seem to be able to instantiate and manifest a causal power (Kim 2003). Given that the evo-devo approach is employing dispositions in a different way, it is important to study whether it is also possible to talk about type dispositions in a relevant metaphysical way.
With this work, connections between metaphysics and biology can be established. These kinds of connections are, in fact, quite common in current philosophy of biology, where metaphysical concepts are used to address conceptual problems in biology (see Boogerd et al. 2005; Dupré 2012; Waters 2017). See, for instance, the the dispositional theory of causation to clarify the biological concept of gene (Mumford and Anjum 2011, ch.10), the appeal to the metaphysical concept of emergence in order to characterise developmental modules in evo-devo (Huneman 2010; Brigandt 2015), or the conceptualization of homologies and body plans as natural kinds (Hall 1996; Griffiths 1999; Rieppel 2006). Generally, philosophy of biology is benefited by using metaphysical concepts insofar as conceptual biological problems addressed by philosophers are clarified using the metaphysical tools. With this project, I want to explore, on the one hand, how evo-devo uses dispositions when attributing them to types, and whether this attribution makes sense from a metaphysical perspective. With this work, it is possible to explore whether evo-devo can be enriched by the resources that metaphysics offers. Furthermore, the study of dispositions in evo-devo might also influence metaphysics. For instance, a potential result is the necessity of developing a metaphysical characterization of type dispositions that are causally relevant. In this sense, this work can illustrate that the interaction between metaphysics and philosophy of biology can be bidirectional, allowing for cases of crossfertilization (In this regard, see Reyon 2008).