Abstract
When talking about personal identity in the context of medical ethics, ethicists tend to borrow haphazardly from different philosophical notions of personal identity, or to abjure these abstract metaphysical concerns as having nothing to do with practical questions in medical ethics. In fact, however, part of the moral authority for respecting a patient’s self-regarding decisions can only be made sense of if we make certain assumptions that are central to a particular, psychological picture of personal identity, namely, that patients will remain psychologically connected to a certain degree with their future selves. I draw this out, show problems with approaches in medical ethics based on alternate theories of personal identity that do not recognise this, and explore some important implications. Namely, I show how this recognition can better explain the circumstances under which we should respect advance directives and why, and how it can better make sense of patient fears that they will not "survive" personality-altering deep brain stimulation procedures, and provide guidance on approaching patient decisions concerning this type of procedure in a manner that captures and addresses such concerns.