 One topic which has always loomed large in this debate has been the issue (in the terminology of Lewis 1986, Ch. 4) of perdurance versus endurance. (Others, for which there is no space for discussion here, include the debate over Ship of Theseus and reduplication or fission problems and associated issues about “best candidate” or “no rival candidate” accounts of identity over time, and the debate over Humean supervenience – see articles on relative identity, personal identity, Hawley 2001 and Sider 2001.)