Abstract

The Diachronic Self fills out and clarifies the account of personal identity presented by Derek Parfit in Reasons and Persons. I go on to draw metaphysical and normative consequences of this psychological reductionist theory. Some of the normative inferences disagree with those of Parfit. I examine several candidates for a necessary causal condition for personal identity or continuity and argue that we should accept one of the most liberal conditions, allowing personal identity to persist even if its cause is abnormal and unreliable. After establishing a causal condition for identity I apply psychological reductionism to critically analyze current conditions of and criteria for the death of persons. I argue that cardiac and consciousness based conceptions are incorrect. In their place I offer an information-based conception. I then go on to examine the relative importance of various psychological connections, including memories, intentions, dispositions, beliefs, desires, values, and projects. It turns out that the significance of passive elements of the self, especially memories, has often been overrated in discussions of identity. Drawing on my metaphysical results, I draw a number of normative conclusions. I differ from Parfit in holding that reductionism does not make life less "deep" nor death less significant. I also argue that Parfit puts too much emphasis on connectedness rather than continuity when assessing the rational apportionment of future-concern. I look at the roles of an ideal self-conception, life plans, and principles in generating and sustaining concern for one's farther future self-stages. The final chapter analyses how we assimilate changes in our selves, especially physical changes resulting from technology. I distinguish augmentative from deteriorative changes, and draw normative inferences about whether rationally we should replace ourselves with a better self, if that were possible. I develop an account of assimilation in terms of functional integration, then go on to distinguish enhancement from supplementation, noting the importance of this for normative concerns. Finally, I determine the role of bodily form and function in a psychological reductionist account of personal identity