Abstract

In this dissertation, I explore the reach of the Evolutionary Contingency Thesis—a view that emphasizes the role of dependency relations and chance in evolution. Contingency produces diverse biological entities, processes, and mechanisms. I analyze the implications of evolution’s contingency in three areas. First, I address the problem of evolutionary individuality, which concerns the nature of entities that selection acts on. If we accept Lewontin’s 1970 view that individuals are selected, then what exactly are these individuals? I argue that evolutionary contingency and its diversity of outcomes causes a plurality of individuality types. These types of individuals emerge, evolve, and disappear through evolution. Second, I defend a disunified model of major transitions in evolution. Major transitions mark pivotal turning points in life’s history, such as the transition from unicellularity to multicellularity. Philosophers and biologists aim to unify evolution’s transitions by establishing a property all major events share. I argue that evolutionary contingency’s emphasis on diversity supports a disunified model of transitions. That is, we should expect numerous kinds of major transitions given the diverse sets of outcomes caused by evolutionary contingency. Finally, I extend the contingency analysis to a topic in philosophy of medicine: The nature of cancer. It is common to view cancer as a by-product of our evolution as multicelled creatures. However, Lean and Plutynski argue that cancer is also a direct product of evolution by selection. In both cases, cancer is characterized in terms of how it functions as an object of selection. I argue that the diversity among cancers suggests philosophers should shift their focus to cancers’ structural differences rather than only their functional similarities.