Our understanding of dementia is shaped by cultural tropes. Such tropes may be helpful in making sense of an otherwise elusive and ultimately inscrutable state. In contemporary discourses on dementia, two tropes play a prominent role: the ‘return to childhood and the ‘living death. This article subjects both cultural tropes to critical reflection. It first explains the cultural-historical origin and meaning of the ‘second childhood and ‘living death metaphors. It then explores their implications for our understanding of dementia and our attitudes and behaviors towards those affected. In doing so, it employs a life-course approach that draws attention to the normative significance of the temporal dimension and structural whole of a human life. In this way, it turns out that both metaphors essentially compare dementia with a different stage in human life and thus regard the condition as a deviation from biographical norms. The article then draws conclusions for ethical debates about self-determination, substitute decision-making and advance directives of people with dementia. Moreover, on a theoretical-conceptual level, it highlights the significance of a biographical and cultural-sensitive perspective for ethical theorizing.