Species are central to biology, but there is currently no agreement on what the adequate species concept should be, and many have adopted a pluralist stance: different species concepts will be required for different purposes. This thesis is a multidimensional analysis of species pluralism. First I explicate how pluralism differs monism and relativism. I then consider the history of species pluralism. I argue that we must re-frame the species problem, and that re-evaluating Aristotle's role in the histories of systematics can (...) shed light on pluralism. Next I consider different forms of pluralism: evolutionary and extra-evolutionary species pluralism, which differ in their stance on evolutionary theory. I show that pluralism is more than a debate about the species category, but a debate about which concepts are legitimate and a claim about how they interact with one another. Following that, I consider what sort of ontology is required for different forms of species pluralism. I argue that pluralists who deny the unity of biology will require a further plurality of frameworks, while those that ground their pluralism in evolution need only one framework. Finally, I consider what pluralism means for biological practice. I argue that species concepts are tools, and reflect on how pluralism can illuminate the way systematists approach the discovery of new species of yeast. Pluralism can make sense of the way species concepts are used, and can be developed to aid researchers in thinking about how to use the right tools for the right jobs. (shrink)

Abstract The ‘species problem’ in the philosophy of biology concerns the nature of species. Various solutions have been proposed, including arguments that species are sets, classes, natural kinds, individuals, and homeostatic property clusters. These proposals parallel debates in ecology as to the ontology and metaphysics of populations, communities and ecosystems. A new solution—that species are processes—is proposed and defended, based on Robert Ulanowicz’s metaphysics of process ecology. As with ecological systems, species can be understood as emergent, autocatalytic systems with propensities (...) for centripetality and mutuality in the course of dynamically balancing ascendency (order and persistence) and overhead (randomness and change). The species-as-processes perspective accords with the Ulanowicz’s postulates of process ecology and it can be accommodated by existing theories of species—particularly in a reframing of Richard Boyd’s metaphysics such that species are homeostatic process clusters. Rather than contending that process-based metaphysics is the only, best or true account of species, a pluralist-realist approach is advocated based on the pragmatic principles that are reflected in modern view of species and ecology. If species are understood to be comprised of processes and to be emergent processes themselves, there are important implications for the life sciences, including: animal models in medical and environmental studies, conservation biology, extinction, biodiversity, restoration ecology, and evolutionary biology. Content Type Journal Article Category Invited Paper Pages 1-30 DOI 10.1007/s10516-011-9169-5 Authors Jeffrey A. Lockwood, Department of Philosophy, University of Wyoming, Laramie, WY 82071, USA Journal Axiomathes Online ISSN 1572-8390 Print ISSN 1122-1151. (shrink)