In both scientific and popular circles it is often said that we are in the midst of a sixth mass extinction. Although the urgency of our present environmental crises is not in doubt, such claims of a present mass extinction are highly controversial scientifically. Our aims are, first, to get to the bottom of this scientific debate by shedding philosophical light on the many conceptual and methodological challenges involved in answering this scientific question, and, second, to offer new philosophical perspectives (...) on what the value of asking this question has been — and whether that value persists today. We show that the conceptual challenges in defining ‘mass extinction’, uncertainties in past and present diversity assessments, and data incommensurabilities undermine a straightforward answer to the question of whether we are in, or entering, a sixth mass extinction today. More broadly we argue that an excessive focus on the mass extinction framing can be misleading for present conservation efforts and may lead us to miss out on the many other valuable insights that Earth’s deep time can offer in guiding our future. (shrink)

Phylogenetic models traditionally represent the history of life as having a strictly-branching tree structure. However, it is becoming increasingly clear that the history of life is often not strictly-branching; lateral gene transfer, endosymbiosis, and hybridization, for example, can all produce lateral branching events. There is thus motivation to allow phylogenetic models to have a reticulate structure. One proposal involves the reconciliation of genealogical discordance. Briefly, this method uses patterns of disagreement – discordance – between trees of different genes to add (...) lateral branching events to phylogenetic trees of taxa, and to estimate the most likely cause of these events. I use this practice to argue for: (1) a need for expanded accounts of multiple-models idealization, (2) a distinction between automatic and manual de-idealization, and (3) recognition that idealization may serve the meso-level aims of science in a different way than hitherto acknowledged. (shrink)

This dissertation investigates Plato’s prohibition on suicide at Phaedo 62b2-c9. I first lift two descriptions of death early in the text. At Phaedo 64c, Plato offers a description of physical death. A person dies physically when their body falls away from their soul. Plato goes on to offer a description of psychological death at 67c-d. A person dies psychologically when their soul has unencumbered itself from the body as much as is possible. Generally, I conclude, death is the separation of (...) the soul and body from one another. Having determined what death is for Plato, I turn to the central topic of the dissertation, Plato’s prohibition on suicide. I suggest that the suicide prohibition consists of two parts. The Enclosure Argument indicates the body is an enclosure from which we should not seek freedom so as not to defy the gods. The Guardian Argument indicates that we humans should not kill ourselves because we are enslaved to the gods. In all, the two arguments cohere insofar as they both tell against abandoning right rule. (shrink)