Essentialist Heuristics in Biology

I offer a framework for understanding and explaining the apparent occurrence of essentialism in biology. While essentialism in the philosophy of biology has generally referred to various metaphysical theses regarding kinds, I argue that these moves are often best understood as essentialist heuristics; a group of related conceptual tools that make essentialist assumptions. But because they are heuristic, they carry no strong metaphysical commitment. These heuristics have systematic, predictable patterns of success and failure that biologists use to learn about the world.;I begin by describing discussions of essentialism within the philosophy of biology, and how they have mostly pertained to discussions of species concepts. I claim that despite arguments against essentialism, essentialist assumptions of various types pervade biology, and not just with respect to species. I argue that this presents us with two major problems to solve: an explanatory one as to why talk of essentialism and practices that may suggest metaphysical commitments occur, and a normative one as to what is either advisable or inadvisable about making such assumptions. I argue that resolving metaphysical issues does not give us adequate resources to solve either problem.;I then develop my framework of essentialist heuristics. This begins with a description of "working essentialism" that occurs when biologists make essentialist assumptions that are invested with resources. Working essentialism can be deployed as heuristics when the assumptions are used in particular ways to learn about the world. I describe how this works and then offer a "field guide" for identifying and analyzing essentialist heuristics.;I proceed to analyze two major sets of case studies. The first set comes from invasion biology. I argue that invasion biologists have used several essentialist heuristics in the search for predictive generalizations, the clarification of central theoretical concepts, and the design of experiments. My second set of case studies comes from evolutionary biology. I argue that a recent proposal to replace sexual selection theory with social selection theory has revealed functioning essentialist heuristics within sexual selection theory.;I finish by describing two more areas of biology to which my framework could be applied: subspecies in ornithology, and discussions of species concepts.