No worries for Captain Kirk, pace Brueckner (or at least different worries)
Anthony Brueckner (2005) argues that Derek Parfit's (1984) psychological approach to personal identity faces a problem because of its need for a 'non-branching clause'. No such clause is required if the world-tube ver sion of transtemporal identity which Parfit uses is replaced by Ted Sider's (1996, 2001) 'stage theory'. Take the seminal example where Scotty beams Captain Kirk up to Starship Enterprise. On Parfit's analysis Kirk faces an identity crisis if two or more replicas of his body are produced by the receiving apparatus, but that is not so according to stage theory. Sider has introduced the idea of temporal counterparts, analogous to David Lewis's modal counterparts. In ordinary non-teleportational circumstances Kirk at time T and Kirk at the later time T+ are two distinct people who are temporal counterparts. Kirk-at-T will be Kirk-at-T-tand Kirk-at-T+ was Kirk-at-T. When it comes