 Certain puzzle cases also seem to suggest that a person might divide into two: suppose that, as a result of philosophical confusion on the hospital ethics committee, a doctor is permitted to remove the two halves of your brain and implant them into two different (brainless) bodies. On one understanding of this process, each of the resulting people has a good claim to be you. Is this a reason to think that two coincident people were walking around together before the operation, and that they have only now been separated?