Abstract

With some notable exceptions (Hall 1992, 2003, 2012; Minelli 1996, 2003; Brigandt 2007; Love 2007; Ereshefsky 2012, Wagner 2016), the continued debate over the meaning of homology within philosophy and history of biology over the last 25 years has focused on defining homology rather than on its use in practice. Those focusing on scientific practice in a number of disciplines from linguistics to chemistry claim that knowledge is always understood with reference to a particular context and in light of the actions of epistemic agents. Knowledge-making activities are not the result of universal rules for deriving explanation from facts but the result of critical intersubjective modes of investigation in “systems of practice” (Chang 2012, 2016). It would seem then that taking a science-in-practice approach would, if used to understand the meaning and role of homology, turn attention to the activities of homologizing and communication between scientists in order to characterize the nature of inquiry within comparative biology (Kendig 2016). But does this emphasis on practice imply a kind of eliminitivism with regard to metaphysics? If not, what is the relationship between the underlying metaphysical commitments that make homologizing possible, (e.g., non-empirical considerations), empirical practices, and knowledge-making activities? I employ Chakravartty’s (2017) notion of “metaphysical inference” in order to suggest an alternative practice-based approach. In doing so I attempt to show how metaphysical inference affects homologizing activities in at least three ways: 1) in the articulation of the nature of continuity, 2) the specification of the units of comparison, and 3) the individuation of parts. An attempt to answer the question which is the title of this talk, How can we homologize holobionts, and whose lineage matters?, is made by investigating how specific metaphysical inferences work, in situ, for lichen physiology and classification. Lichens are made up of multiple organisms that can themselves be members of three kingdoms. I explore what the nature of continuity and individuation means for being a lichen and how lichenologists consider lineage.