Abstract

Michael Ghiselin and David Hull’s individuality thesis is that biological species are individuals. Philosophers often treat the term “individual” as synonymous with “mereological sum” and characterize it in terms of mereology. It is easy to see how the biological project has been interpreted as a mereological one. This chapter argues that this is a mistake, that biological part/whole relations often violate the axioms of mereology. Conflating these projects confuses the central issues at stake in both, and makes the job of evaluating either unnecessarily burdensome. Clarifying this helps identify the genuine metaphysical implications of the individuality thesis, which serves as an exemplar of scientifically informed metaphysics.