UC Santa Barbara

In this dissertation, I defend an answer to the following question in the diachronic personal identity debate: what are the necessary and sufficient conditions for our persistence over time? Two popular approaches to answering this question are the psychological and the somatic approach. On the former approach, we persist in virtue of some sort of psychological continuity. So, some proponents of the psychological approach think that we cease to exist if we lose certain features of our psychology such as our memories, beliefs, and rationality. On the latter approach, we persist in virtue of some sort of physical continuity. Eric Olson defends a version of the somatic approach called animalism. On his view, we are numerically identical to biological organisms and we persist if and only if the organisms we are persist. Although Olson’s animalism has some benefits, it also faces some challenges. For example, many people would say that we go wherever our brains go (if we go anywhere at all) because our brains (more specifically, our cerebra) realize the aspects of our psychology traditionally associated with persons, such as memories, beliefs, rationality, and self-awareness. But on Olson’s animalism, our psychology has nothing to do with our persistence and we go wherever our bodies go rather than our cerebra. Following Aristotle and Aquinas, I lay out an animalist view of our persistence called hylomorphic animalism. On this view, we are numerically identical to rational animals, which are living bodies composed of prime matter and a rational soul. Furthermore, we persist if and only if the composite of matter and rational soul persists. I claim that hylomorphic animalism makes better sense of certain contemporary personal identity thought experiments than Olson’s animalism. For example, contra Olson, I argue that our psychology does have something to do with our persistence and that we go wherever our brains go.