Derek Parfit – the psychological view of personal identity
Advance directives and personhood Parfit takes the view that
personal identity is constituted over time by varying degrees of
continuity between former and later selves in terms of a wide
range of psychological and physical features. The psychological
aspect of personal identity is constituted by the degrees of
similarity between two temporally separate selves with regard to
a person’s personality, belief structure and desires, which may
in certain cases (such as advanced dementia) depending on the
degree of similarity and continuity, move from being intra-
personal to being inter-personal. In certain cases of advanced
dementia, it could be argued that psychological continuity is so
deeply disturbed that someone has become another person. In such
cases, an advance directive should have no more moral force in
connection to the course of action to be currently taken than it
would have had, had it been written by a stranger, friend or
relative. A person w