Diversity in unity: practical unity and personal boundaries

In the spirit of the discussion in Daniel Kolak's I Am You: The Metaphysical Foundation for Global Ethics, I consider the way in which divisions that we usually think of as borders between distinct people occur within a single life. Starting with the dispute between constructionist and non-constructionist views of persons, I argue for a view that places the unity of persons in the dynamic generated by simultaneously taking a constructionist and non-constructionist view of oneself. In order to unify ourselves as agents we need to treat past and future selves as others, but to motivate this endeavor we need to think of ourselves as temporally extended agents, and so identify with past and future selves. Understanding this dynamic illuminates the structure of our agency and the unity of the self.