"Dementia" suggests that the person is out of his or her mind. This is stigmatizing, especially given that, even into severe dementia, there is evidence that the person living with dementia remains minded. But this leads us on to consider different theories relating to the nature of the mind. This chapter discusses dualist interactionism, eliminative materialism, functionalism, social constructionism and externalism. In each case two questions are posed: First, does philosophy of mind give us insights into the nature of dementia? Secondly, what can we learn about mind (from the perspective of any particular theory) by studying people with dementia? The conclusions are that we need to have a broad understanding of what constitutes mind and that, for people with dementia, it is important to see them holistically as persons.