| To date, the attempt to find necessary and sufficient conditions for personal identity has not been successful. Both psychological and physical criteria have failed to capture important intuitions about what it is to be the same self over time: moreover, they yield counter-intuitive and often bizarre results. I argue that the driving force behind these counter-intuitive approaches to the self is what I call the discreteness assumption, an assumption which is generally not explicitly recognized. This assumption holds that the real self must be that which has discrete boundaries and persists unchanged. Various responses have been made to these failures: some argue that there is no self and others focus solely on characterization, leaving metaphysical considerations aside. However, these responses do not seem adequate, nor do they take the biological aspect of persons into serious account. Furthermore, they are formed in reaction to the implausibility of the discreteness assumption, not because they are particularly informative about personal identity themselves. If conceptual progress is to be made, commitment to the discreteness assumption, whether explicit or not, must be abandoned. In virtue of the special problems that theoretical immunologists must solve, immunology provides a source of novel ideas about the self that have not been influenced by this assumption. I argue that one of these ideas suggests a solution to the problem of personal identity: and this is the idea that the immune self is a process. According to this view, the immune self is a self over time in virtue of constant self-redefinition, self-imaging and self-creation. Combining this idea with recent interpretations of Hume's view of the self, I argue that selves have a modified version of numerical identity over time. The test set by the discreteness assumption for criteria of personal identity is stricter than is warranted by our everyday experience of selves in the world: such unrealistic expectations are not likely to be satisfied, and, moreover, they do not need to be satisfied. It is only through a more relaxed notion of identity that conceptual progress will be made; and the process view of the immune self provides a model for just such a notion. |
