Personal identity and rationality

• Main Author: Cave, S.
• Published: University of Cambridge 2001
• Subjects: 100
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.597374

There are two ways in which a theory of personal identity can diverge from that most fundamental tenet of practical reason, self-concern. The first is if it is irrational to be concerned for one's own future (the Nihilistic Thesis). The second is if it is rational for one to be concerned, in the way in which one is ordinarily concerned for only oneself, about someone else's future (the Optimistic Thesis). Most theories of personal identity either claim to entail, or have been accused of entailing one or other of these theses. Yet they are both absurd. In this dissertation, I ask which theories of personal identity are compatible with practical reason. In Chapter One, I introduce three views of personal identity which reflect the major themes in the current debate: an animalist view, a brain-based view, and a psychology-based view. Whilst it is widely accepted that a view of personal identity is in difficulty if it entails that it is irrational for someone to be prudentially concerned about their own future, some views have embraced the idea that someone might be prudentially concerned about someone else's future. In Chapter Two and Three, I explore each of these possibilities in turn, and show how they both entail contradiction and absurdity. In Chapter Four, I develop the necessary and sufficient conditions for prudential concern, with which to determine which views of personal identity entail the Nihilistic and Optimistic Theses. In Chapter Five, I show that the psychology-based view entails both the Nihilistic and Optimistic Theses, and is therefore false. In Chapter Six, I show how the brain-based and animalist views <I>could</I> entail both theses, but conclude that, on current evidence, the animalist view does not entail either, and is therefore most compatible with practical reason.