This paper revisits Ronald Dworkin’s influential position that a person’s advance directive for future health care and medical treatment retains its moral authority beyond the onset of dementia, even when respecting this authority involves foreshortening the life of someone who is happy and content and who no longer remembers or identifies with instructions included within the advance directive. The analysis distils a eudaimonist perspective from Dworkin’s argument and traces variations of this perspective in further arguments for the moral authority of (...) advance directives by other authors. It then critiques a feature of the eudaimonist perspectives within these arguments—namely, the position that dementia has a retroactive negative impact on what a person has previously valued—and challenges the commonly held assumption underlying them that a person’s life and well-being have relatively low value beyond the onset of dementia. Although advance directives have moral authority as a means of guiding one’s future health care, accounts that dismiss the value of the lives and well-being of people living with dementia should be questioned to the extent that such accounts are used to support the moral authority of advance directives stipulating measures to foreshorten individuals’ lives. (shrink)