Abstract
David lewis has argued that--Despite the 'fission' cases--One may consistently hold both that what matters in survival is "mental continuity and connectedness" and that what matters in survival is identity. To prove his point, He produces a certain theory of persons. Derek parfit and penelope maddy have objected that the theory lewis produces does not actually have the advantages he claims for it. In this paper, The author questions their objections, And then argues that, Even though lewis's theory has many virtues, No sufficiently knowledgeable person can be justified in accepting it (here and now) as an adequate theory of persons