Minds under failure, minds from inside
Which capacity, if you lost it, would end the person you think you are?
What it argues
Neurological patients lose capacities and rebuild selves around the loss: a man who cannot recognise faces, a woman who cannot feel her body, a man who cannot form new memories. The cases show identity as assembled and revisable rather than given.
The probe
Name the one capacity whose loss would end the person you think you are. Then ask how much of your week maintains it.
The source
The Man Who Mistook His Wife for a Hat — Oliver Sacks, 1985. The link goes to the text or to a catalogue record for it, not to a summary. This one is a catalogue record: the entry gives you the question and the probe, not the argument in the author's words.