Personal Derek Parfit [1] We can, I think, describe cases in which, though we know the answer to every other question, we have no idea how to answer...

Personal Derek Parfit [1] We can, I think, describe cases in which, though we know the answer to every other question, we have no idea how to answer a question about personal identity. These cases are not covered by the criteria of personal identity that we actually use. Do they present a problem?